FAA-H-8083-3B Airplane Flying Handbook, 2016

WIND WIND longitudinal axis aligned with the runway. In other words, the drift is controlled with aileron and the heading with rudder. The airplane is now side slipping into the wind just enough that both the resultant flightpath and the ground track are aligned with the runway. If the crosswind diminishes, this crosswind correction is reduced accordingly, or the airplane begins slipping away from the desired approach path. [Figure 8-17] Figure 8-15. Crabbed approach. To correct for strong crosswind, the slip into the wind is increased by lowering the upwind wing a considerable airplane must be aligned with the runway to avoid sideward amount. As a consequence, this results in a greater tendency contact of the wheels with the runway. If a long final approach of the airplane to turn. Since turning is not desired, is being flown, one option is to use the crab method until just considerable opposite rudder must be applied to keep the before the round out is started and then smoothly change to airplane’s longitudinal axis aligned with the runway. In some the wing-low method for the remainder of the landing. airplanes, there may not be sufficient rudder travel available to compensate for the strong turning tendency caused by the The wing-low (sideslip) method compensates for a crosswind steep bank. If the required bank is such that full opposite from any angle, but more important, it keeps the airplane’s rudder does not prevent a turn, the wind is too strong to ground track and longitudinal axis aligned with the runway safely land the airplane on that particular runway with those centerline throughout the final approach, round out, wind conditions. Since the airplane’s capability is exceeded, touchdown, and after-landing roll. This prevents the airplane it is imperative that the landing be made on a more favorable from touching down in a sideward motion and imposing runway either at that airport or at an alternate airport. damaging side loads on the landing gear. Flaps are used during most approaches since they tend to have To use the wing-low method, align the airplane’s heading a stabilizing effect on the airplane. The degree to which flaps with the centerline of the runway, note the rate and direction are extended vary with the airplane’s handling characteristics, of drift, and promptly apply drift correction by lowering as well as the wind velocity. the upwind wing. [Figure 8-16] The amount the wing must be lowered depends on the rate of drift. When the wing Crosswind Round Out (Flare) is lowered, the airplane tends to turn in that direction. To Generally, the round out is made like a normal landing compensate for the turn, it is necessary to simultaneously approach, but the application of a crosswind correction is apply sufficient opposite rudder pressure to keep the airplane’s continued as necessary to prevent drifting. Since the airspeed decreases as the round out progresses, the flight controls gradually become less effective. As a result, the crosswind correction being held becomes inadequate. When using the wing-low method, it is necessary to gradually increase the deflection of the rudder and ailerons to maintain the proper amount of drift correction. Figure 8-16. Sideslip approach. Do not level the wings and keep the upwind wing down throughout the round out. If the wings are leveled, the airplane begins drifting and the touchdown occurs while drifting. Remember, the primary objective is to land the airplane without subjecting it to any side loads that result from touching down while drifting. Crosswind Touchdown If the crab method of drift correction is used throughout the final approach and round out, the crab must be removed the instant before touchdown by applying rudder to align the airplane’s longitudinal axis with its direction of movement. This requires timely and accurate action. Failure to 8-15

WIND 34 Figure 8-17. Crosswind approach and landing. accomplish this results in severe side loads being imposed of rudder or nose-wheel steering, while keeping the upwind on the landing gear. wing from rising by the use of aileron. When an airplane is airborne, it moves with the air mass in which it is flying If the wing-low method is used, the crosswind correction regardless of the airplane’s heading and speed. When an (aileron into the wind and opposite rudder) is maintained airplane is on the ground, it is unable to move with the air throughout the round out, and the touchdown made on the mass (crosswind) because of the resistance created by ground upwind main wheel. During gusty or high wind conditions, friction on the wheels. prompt adjustments must be made in the crosswind correction to assure that the airplane does not drift as the airplane Characteristically, an airplane has a greater profile or side touches down. As the forward momentum decreases after area behind the main landing gear than forward of the gear. initial contact, the weight of the airplane causes the downwind With the main wheels acting as a pivot point and the greater main wheel to gradually settle onto the runway. surface area exposed to the crosswind behind that pivot point, the airplane tends to turn or weathervane into the wind. In those airplanes having nose-wheel steering interconnected with the rudder, the nose wheel is not aligned with the runway Wind acting on an airplane during crosswind landings is the as the wheels touch down because opposite rudder is being result of two factors. One is the natural wind, which acts held in the crosswind correction. To prevent swerving in in the direction the air mass is traveling, while the other the direction the nose wheel is offset, the corrective rudder is induced by the forward movement of the airplane and pressure must be promptly relaxed just as the nose wheel acts parallel to the direction of movement. Consequently, touches down. a crosswind has a headwind component acting along the airplane’s ground track and a crosswind component acting Crosswind After-Landing Roll 90° to its track. The resultant or relative wind is somewhere Particularly during the after-landing roll, special attention between the two components. As the airplane’s forward must be given to maintaining directional control by the use speed decreases during the after landing roll, the headwind 8-16

component decreases and the relative wind has more of a 60 crosswind component. The greater the crosswind component, the more difficult it is to prevent weathervaning. Maintaining control on the ground is a critical part of the 50 Danger Zone after-landing roll because of the weathervaning effect of 40 the wind on the airplane. Additionally, tire side load from Wind Velocity (mph) runway contact while drifting frequently generates roll-overs in tricycle-geared airplanes. The basic factors involved are cornering angle and side load. Cornering angle is the angular difference between the heading 30 of a tire and its path. Whenever a load bearing tire’s path and heading diverge, a side load is created. It is accompanied by 20 tire distortion. Although side load differs in varying tires and air pressures, it is completely independent of speed, 10 and through a considerable range, is directly proportional to the cornering angle and the weight supported by the tire. As Direct crosswind little as 10° of cornering angle creates a side load equal to half the supported weight; after 20°, the side load does not 0 100 increase with increasing cornering angle. For each high-wing, 20 40 60 80 tricycle-geared airplane, there is a cornering angle at which Wind Angle (degrees) roll-over is inevitable. The roll-over axis is the line linking the nose and main wheels. At lesser angles, the roll-over Figure 8-18. Crosswind chart. may be avoided by use of ailerons, rudder, or steerable nose wheel but not brakes. demonstrated crosswind velocity be included on a placard in airplanes certificated after May 3, 1962. While the airplane is decelerating during the after-landing roll, more and more aileron is applied to keep the upwind The headwind component and the crosswind component for wing from rising. Since the airplane is slowing down, there a given situation is determined by reference to a crosswind is less airflow around the ailerons and they become less component chart. [Figure 8-19] It is imperative that pilots effective. At the same time, the relative wind becomes more determine the maximum crosswind component of each of a crosswind and exerting a greater lifting force on the airplane they fly and avoid operations in wind conditions upwind wing. When the airplane is coming to a stop, the that exceed the capability of the airplane. aileron control must be held fully toward the wind. Common errors in the performance of crosswind approaches Maximum Safe Crosswind Velocities and landings are: Takeoffs and landings in certain crosswind conditions are inadvisable or even dangerous. [Figure 8-18] If the crosswind • Attempting to land in crosswinds that exceed the is great enough to warrant an extreme drift correction, a airplane’s maximum demonstrated crosswind hazardous landing condition may result. Therefore, the component takeoff and landing capabilities with respect to the reported surface wind conditions and the available landing directions • Inadequate compensation for wind drift on the must be considered. turn from base leg to final approach, resulting in undershooting or overshooting Before an airplane is type certificated by the Federal Aviation Administration (FAA), it must be flight tested and meet • Inadequate compensation for wind drift on final certain requirements. Among these is the demonstration of approach being satisfactorily controllable with no exceptional degree of skill or alertness on the part of the pilot in 90° crosswinds • Unstable approach up to a velocity equal to 0.2 VSO. This means a windspeed of two-tenths of the airplane’s stalling speed with power off and landing gear/flaps down. Regulations require that the 8-17

0° 10° One procedure is to use the normal approach speed plus 70 20° one-half of the wind gust factors. If the normal speed is 60 30° 70 knots, and the wind gusts are 15 knots, an increase of 50 airspeed to 77 knots is appropriate. In any case, the airspeed Headwind Component Wind velocity 40° and the number of flaps used should conform to airplane 50° manufacturer recommendations in the AFM/POH. 40 60° Use an adequate amount of power to maintain the proper 30 70° airspeed and descent path throughout the approach, and 20 retard the throttle to idling position only after the main 10 80° wheels contact the landing surface. Care must be exercised in closing the throttle before the pilot is ready for touchdown. 0 10 20 30 40 50 90° In turbulent conditions, the sudden or premature closing of Crosswind Component 60 70 the throttle may cause a sudden increase in the descent rate that results in a hard landing. Figure 8-19. Crosswind component chart. When landing from power approaches in turbulence, the • Failure to compensate for increased drag during touchdown is made with the airplane in approximately level sideslip resulting in excessive sink rate and/or too low flight attitude. The pitch attitude at touchdown would be only an airspeed enough to prevent the nose wheel from contacting the surface before the main wheels have touched the surface. After • Touchdown while drifting touchdown, avoid the tendency to apply forward pressure on the yoke, as this may result in wheel barrowing and possible • Excessive airspeed on touchdown loss of control. Allow the airplane to decelerate normally, assisted by careful use of wheel brakes. Avoid heavy braking • Failure to apply appropriate flight control inputs until the wings are devoid of lift and the airplane’s full weight during rollout is resting on the landing gear. • Failure to maintain direction control on rollout Short-Field Approach and Landing • Excessive braking Short-field approaches and landings require the use of procedures for approaches and landings at fields with • Loss of aircraft control a relatively short landing area or where an approach is made over obstacles that limit the available landing area. Turbulent Air Approach and Landing [Figures 8-20 and 8-21] As in short-field takeoffs, it is one of the most critical of the maximum performance operations. For landing in turbulent conditions, use a power-on approach Short field operations require the pilot fly the airplane at at an airspeed slightly above the normal approach speed. This one of its crucial performance capabilities while close to the provides for more positive control of the airplane when strong ground in order to safely land within confined areas. This horizontal wind gusts, or up and down drafts, are experienced. low-speed type of power-on approach is closely related to Like other power-on approaches, a coordinated combination the performance of flight at minimum controllable airspeeds. of both pitch and power adjustments is usually required. As in most other landing approaches, the proper approach attitude To land within a short-field or a confined area, the pilot and airspeed require a minimum round out and should result must have precise, positive control of the rate of descent and in little or no floating during the landing. airspeed to produce an approach that clears any obstacles, result in little or no floating during the round out, and permit To maintain control during an approach in turbulent air the airplane to be stopped in the shortest possible distance. with gusty crosswind, use partial wing flaps. With less than full flaps, the airplane is in a higher pitch attitude. Thus, it The procedures for landing in a short-field or for landing requires less of a pitch change to establish the landing attitude approaches over obstacles as recommended in the AFM/ and touchdown at a higher airspeed to ensure more positive POH should be used. A stabilized approach is essential. control. Excessive speed causes the airplane to float past the [Figures 8-22 and 8-23] These procedures generally involve desired landing area. the use of full flaps and the final approach started from an 8-18

Obstacle clearance 34 Effective runway length Effective runway length Figure 8-20. Landing over an obstacle. 34 34 Non-obstacle clearance Figure 8-21. Landing on a short-field. Stabilized Figure 8-22. Stabilized approach. 8-19

34 Unstabilized Figure 8-23. Unstabilized approach. altitude of at least 500 feet higher than the touchdown area. A to as operating in the region of reversed command or operating wider than normal pattern is normally used so that the airplane on the back side of the power curve. When there is doubt can be properly configured and trimmed. In the absence of regarding the outcome of the approach, make a go around and the manufacturer’s recommended approach speed, a speed try again or divert to a more suitable landing area. of not more than 1.3 VSO is used. For example, in an airplane that stalls at 60 knots with power off, and flaps and landing Because the final approach over obstacles is made at a gear extended, an approach speed no higher than 78 knots relatively steep approach angle and close to the airplane’s is used. In gusty air, no more than one-half the gust factor stalling speed, the initiation of the round out or flare must be is added. An excessive amount of airspeed could result in judged accurately to avoid flying into the ground or stalling a touchdown too far from the runway threshold or an after- prematurely and sinking rapidly. A lack of floating during landing roll that exceeds the available landing area. the flare with sufficient control to touch down properly is verification that the approach speed was correct. After the landing gear and full flaps have been extended, simultaneously adjust the power and the pitch attitude to Touchdown should occur at the minimum controllable establish and maintain the proper descent angle and airspeed. A airspeed with the airplane in approximately the pitch attitude coordinated combination of both pitch and power adjustments that results in a power-off stall when the throttle is closed. is required. When this is done properly, very little change in Care must be exercised to avoid closing the throttle too the airplane’s pitch attitude and power setting is necessary to rapidly, as closing the throttle may result in an immediate make corrections in the angle of descent and airspeed. increase in the rate of descent and a hard landing. The short-field approach and landing is in reality an accuracy Upon touchdown, the airplane is held in this positive pitch approach to a spot landing. The procedures previously outlined attitude as long as the elevators remain effective. This in the section on the stabilized approach concept are used. If it provides aerodynamic braking to assist in deceleration. appears that the obstacle clearance is excessive and touchdown Immediately upon touchdown and closing the throttle, occurs well beyond the desired spot leaving insufficient room appropriate braking is applied to minimize the after-landing to stop, power is reduced while lowering the pitch attitude to roll. The airplane is normally stopped within the shortest steepen the descent path and increase the rate of descent. If it possible distance consistent with safety and controllability. If appears that the descent angle does not ensure safe clearance the proper approach speed has been maintained, resulting in of obstacles, power is increased while simultaneously raising minimum float during the round out and the touchdown made the pitch attitude to shallow the descent path and decrease the at minimum control speed, minimum braking is required. rate of descent. Care must be taken to avoid an excessively low airspeed. If the speed is allowed to become too slow, an Common errors in the performance of short-field approaches increase in pitch and application of full power may only result and landings are: in a further rate of descent. This occurs when the AOA is so great and creating so much drag that the maximum available • Failure to allow enough room on final to set up the power is insufficient to overcome it. This is generally referred approach, necessitating an overly steep approach and high sink rate 8-20

• Unstable approach The use of flaps during soft-field landings aids in touching • Undue delay in initiating glide path corrections down at minimum speed and is recommended whenever practical. In low-wing airplanes, the flaps may suffer damage • Too low an airspeed on final resulting in inability to from mud, stones, or slush thrown up by the wheels. If flaps flare properly and landing hard are used, it is generally inadvisable to retract them during the • Too high an airspeed resulting in floating on round out after-landing roll because the need for flap retraction is less • Prematurely reducing power to idle on round out important than the need for total concentration on maintaining full control of the airplane. resulting in hard landing • Touchdown with excessive airspeed The final-approach airspeed used for short-field landings is • Excessive and/or unnecessary braking after touchdown equally appropriate to soft-field landings. The use of higher • Failure to maintain directional control approach speeds may result in excessive float in ground effect, and floating makes a smooth, controlled touchdown • Failure to recognize and abort a poor approach that even more difficult. There is no reason for a steep angle of cannot be completed safely descent unless obstacles are present in the approach path. Soft-Field Approach and Landing Touchdown on a soft or rough field is made at the lowest possible airspeed with the airplane in a nose-high pitch Landing on fields that are rough or have soft surfaces, such attitude. In nose-wheel type airplanes, after the main wheels as snow, sand, mud, or tall grass, require unique procedures. touch the surface, hold sufficient back-elevator pressure to When landing on such surfaces, the objective is to touch down keep the nose wheel off the surface. Using back-elevator as smooth as possible and at the slowest possible landing pressure and engine power, the pilot can control the rate speed. A pilot must control the airplane in a manner that the at which the weight of the airplane is transferred from the wings support the weight of the airplane as long as practical wings to the wheels. to minimize drag and stresses imposed on the landing gear by the rough or soft surface. Field conditions may warrant that the pilot maintain a flight condition in which the main wheels are just touching the The approach for the soft-field landing is similar to the normal surface but the weight of the airplane is still being supported approach used for operating into long, firm landing areas. by the wings until a suitable taxi surface is reached. At any The major difference between the two is that during the soft- time during this transition phase, before the weight of the field landing, the airplane is held 1 to 2 feet off the surface in airplane is being supported by the wheels, and before the ground effect as long as possible. This permits a more gradual nose wheel is on the surface, the ability is retained to apply dissipation of forward speed to allow the wheels to touch full power and perform a safe takeoff (obstacle clearance down gently at minimum speed. This technique minimizes and field length permitting) should the pilot elect to abandon the nose-over forces that suddenly affect the airplane at the the landing. Once committed to a landing, the pilot should moment of touchdown. Power is used throughout the level-off gently lower the nose wheel to the surface. A slight addition and touchdown to ensure touchdown at the slowest possible of power usually aids in easing the nose wheel down. airspeed, and the airplane is flown onto the ground with the weight fully supported by the wings. [Figure 8-24] Transition area Ground effect Figure 8-24. Soft/rough field approach and landing. 8-21

The use of brakes on a soft field is not needed and should the approximate spot along a given ground path at which the be avoided as this may tend to impose a heavy load on the airplane lands, regardless of altitude. A pilot who also has the nose gear due to premature or hard contact with the landing ability to accurately estimate altitude, can judge how much surface, causing the nose wheel to dig in. The soft or rough maneuvering is possible during the glide, which is important surface itself provides sufficient reduction in the airplane’s to the choice of landing areas in an actual emergency. forward speed. Often upon landing on a very soft field, an increase in power is required to keep the airplane moving The objective of a good final approach is to descend at an and from becoming stuck in the soft surface. angle that permits the airplane to reach the desired landing area and at an airspeed that results in minimum floating just Common errors in the performance of soft-field approaches before touchdown. To accomplish this, it is essential that both and landings are: the descent angle and the airspeed be accurately controlled. • Excessive descent rate on final approach Unlike a normal approach when the power setting is variable, on a power-off approach the power is fixed at the idle setting. • Excessive airspeed on final approach Pitch attitude is adjusted to control the airspeed. This also changes the glide or descent angle. By lowering the nose • Unstable approach to keep the approach airspeed constant, the descent angle steepens. If the airspeed is too high, raise the nose, and when • Round out too high above the runway surface the airspeed is too low, lower the nose. If the pitch attitude is raised too high, the airplane settles rapidly due to a slow • Poor power management during round out and airspeed and insufficient lift. For this reason, never try to touchdown stretch a glide to reach the desired landing spot. • Hard touchdown Uniform approach patterns, such as the 90°, 180°, or 360° power-off approaches are described further in this chapter. • Inadequate control of the airplane weight transfer from Practice in these approaches provides a pilot with a basis wings to wheels after touchdown on which to develop judgment in gliding distance and in planning an approach. • Allowing the nose wheel to “fall” to the runway after touchdown rather than controlling its descent The basic procedure in these approaches involves closing the throttle at a given altitude and gliding to a key position. Power-Off Accuracy Approaches This position, like the pattern itself, must not be allowed to become the primary objective; it is merely a convenient Power-off accuracy approaches are approaches and landings point in the air from which the pilot can judge whether the made by gliding with the engine idling, through a specific glide safely terminates at the desired spot. The selected key pattern to a touchdown beyond and within 200 feet of a position should be one that is appropriate for the available designated line or mark on the runway. The objective is to altitude and the wind condition. From the key position, the instill in the pilot the judgment and procedures necessary for pilot must constantly evaluate the situation. accurately flying the airplane, without power, to a safe landing. It must be emphasized that, although accurate spot The ability to estimate the distance an airplane glides to a touchdowns are important, safe and properly executed landing is the real basis of all power-off accuracy approaches approaches and landings are vital. A pilot must never sacrifice and landings. This largely determines the amount of a good approach or landing just to land on the desired spot. maneuvering that may be done from a given altitude. In addition to the ability to estimate distance, it requires the ability 90° Power-Off Approach to maintain the proper glide while maneuvering the airplane. The 90° power-off approach is made from a base leg and requires only a 90° turn onto the final approach. The approach With experience and practice, altitudes up to approximately path may be varied by positioning the base leg closer to or 1,000 feet can be estimated with fair accuracy; while above farther out from the approach end of the runway according this level the accuracy in judgment of height above the ground to wind conditions. [Figure 8-25] The glide from the key decreases, since all features tend to merge. The best aid in position on the base leg through the 90° turn to the final perfecting the ability to judge height above this altitude is approach is the final part of all accuracy landing maneuvers. through the indications of the altimeter and associating them The 90° power-off approach usually begins from a with the general appearance of the Earth. The judgment of altitude in feet, hundreds of feet, or thousands of feet is not as important as the ability to estimate gliding angle and its resultant distance. A pilot who knows the normal glide angle of the airplane can estimate with reasonable accuracy, 8-22

1 2 36 3 1. Strong Wind Set up closest base for steeper glideslope on final 2. Medium Wind Set up closer base for steeper glideslope on final 3. Light Wind Set up normal base for normal final Figure 8-25. Plan the base leg for wind conditions. rectangular pattern at approximately 1,000 feet above the so that upon rolling out of the turn, the airplane is aligned ground or at normal traffic pattern altitude. The airplane with the runway centerline. When on final approach, the is flown on a downwind leg at the same distance from the wing flaps are lowered and the pitch attitude adjusted, as landing surface as in a normal traffic pattern. The before necessary, to establish the proper descent angle and airspeed landing checklist should be completed on the downwind (1.3 VSO), then the controls trimmed. Slight adjustments in leg, including extension of the landing gear if the airplane pitch attitude or flaps setting are used as necessary to control is equipped with retractable gear. the glide angle and airspeed. However, never try to stretch the glide or retract the flaps to reach the desired landing spot. The After a medium-banked turn onto the base leg is completed, final approach may be made with or without the use of slips. the throttle is retarded slightly and the airspeed allowed to decrease to the normal base-leg speed. [Figure 8-26] On the After the final-approach glide has been established, full base leg, the airspeed, wind drift correction, and altitude are attention is then given to making a good, safe landing rather maintained while proceeding to the 45° key position. At this than concentrating on the selected landing spot. The base- position, the intended landing spot appears to be on a 45° leg position and the flap setting already determined the angle from the airplane’s nose. probability of landing on the spot. In any event, it is better to execute a good landing 200 feet from the spot than to make The pilot can determine the strength and direction of the wind a poor landing precisely on the spot. from the amount of crab necessary to hold the desired ground track on the base leg. This helps in planning the turn onto the 180° Power-Off Approach final approach and in lowering the correct number of flaps. The 180° power-off approach is executed by gliding with the power off from a given point on a downwind leg to a At the 45° key position, the throttle is closed completely, preselected landing spot. [Figure 8-27] It is an extension of the propeller control (if equipped) advanced to the full the principles involved in the 90° power-off approach just increase revolution per minute (rpm) position, and altitude described. The objective is to further develop judgment in maintained until the airspeed decreases to the manufacturer’s estimating distances and glide ratios, in that the airplane is recommended glide speed. In the absence of a recommended flown without power from a higher altitude and through a speed, use 1.4 VSO. When this airspeed is attained, the nose 90° turn to reach the base-leg position at a proper altitude is lowered to maintain the gliding speed and the controls for executing the 90° approach. trimmed. The base-to-final turn is planned and accomplished 8-23

Power reduced base leg speed Close throttle establish 1.4 VSO Base key position 36 45° Lower partial flaps maintain 1.4 VSO Lower full flaps (as needed) establish 1.3 VSO Figure 8-26. 90° power-off approach. The 180° power-off approach requires more planning and with the type of airplane, but should usually not exceed judgment than the 90° power-off approach. In the execution 1,000 feet above the ground, except with large airplanes. of 180° power-off approaches, the airplane is flown on a Greater accuracy in judgment and maneuvering is required downwind heading parallel to the landing runway. The at higher altitudes. altitude from which this type of approach is started varies Close throttle, normal glide speed 18 Medium or steeper bank 90° 36 Downwind leg key position Lower full flaps (as needed), establish 1.3VSO Key position Lower partial flaps, maintain 1.4 VSO Figure 8-27. 180° power-off approach. 8-24

When abreast of or opposite the desired landing spot, the 360° Power-Off Approach throttle is closed and altitude maintained while decelerating The 360° power-off approach is one in which the airplane to the manufacturer’s recommended glide speed or 1.4 VSO. glides through a 360° change of direction to the preselected The point at which the throttle is closed is the downwind landing spot. The entire pattern is designed to be circular, key position. but the turn may be shallow, steepened, or discontinued at any point to adjust the accuracy of the flightpath. The turn from the downwind leg to the base leg is a uniform turn with a medium or slightly steeper bank. The degree of The 360° approach is started from a position over the bank and amount of this initial turn depend upon the glide approach end of the landing runway or slightly to the side of angle of the airplane and the velocity of the wind. Again, it, with the airplane headed in the proposed landing direction the base leg is positioned as needed for the altitude or wind and the landing gear and flaps retracted. [Figure 8-28] It condition. Position the base leg to conserve or dissipate is usually initiated from approximately 2,000 feet or more altitude so as to reach the desired landing spot. above the ground—where the wind may vary significantly from that at lower altitudes. This must be taken into account The turn onto the base leg is made at an altitude high enough when maneuvering the airplane to a point from which a 90° and close enough to permit the airplane to glide to what would or 180° power-off approach can be completed. normally be the base key position in a 90° power-off approach. After the throttle is closed over the intended point of landing, Although the key position is important, it must not be the proper glide speed is immediately established, and a overemphasized nor considered as a fixed point on the medium-banked turn made in the desired direction so as to ground. Many inexperienced pilots may gain a conception arrive at the downwind key position opposite the intended of it as a particular landmark, such as a tree, crossroad, or landing spot. At or just beyond the downwind key position, other visual reference, to be reached at a certain altitude. the landing gear is extended if the airplane is equipped with This misconception leaves the pilot at a total loss any time retractable gear. The altitude at the downwind key position such objects are not present. Both altitude and geographical should be approximately 1,000 to 1,200 feet above the ground. location should be varied as much as is practical to eliminate any such misconceptions. After reaching the base key After reaching that point, the turn is continued to arrive at a position, the approach and landing are the same as in the 90° base-leg key position, at an altitude of about 800 feet above power-off approach. the terrain. Flaps may be used at this position, as necessary, Normal glide speed Normal glide speed 18 Key position Close throttle, retract flaps 36 Key position Lower partial flaps, maintain 1.4 VSO Lower flaps as needed, establish 1.3VSO Figure 8-28. 360° power-off approach. 8-25

but full flaps are not used until established on the final landing area. From the key point on, the approach is a normal approach. The angle of bank is varied as needed throughout power-off approach. [Figure 8-29] the pattern to correct for wind conditions and to align the airplane with the final approach. The turn-to-final should be With the greater choice of fields afforded by higher altitudes, completed at a minimum altitude of 300 feet above the terrain. the inexperienced pilot may be inclined to delay making a decision, and with considerable altitude in which to Common errors in the performance of power-off accuracy maneuver, errors in maneuvering and estimation of glide approaches are: distance may develop. • Downwind leg is too far from the runway/landing area All pilots must learn to determine the wind direction and estimate its speed from the windsock at the airport, smoke • Overextension of downwind leg resulting from a from factories or houses, dust, brush fires, and windmills. tailwind Once a field has been selected, a pilot should always • Inadequate compensation for wind drift on base leg be required to indicate the proposed landing area to the instructor. Normally, the pilot should be required to plan • Skidding turns in an effort to increase gliding distance and fly a pattern for landing on the field first elected until the instructor terminates the simulated emergency landing. • Failure to lower landing gear in retractable gear This provides the instructor an opportunity to explain and airplanes correct any errors; it also gives the pilot an opportunity to see the results of the errors. However, if the pilot realizes • Attempting to “stretch” the glide during an undershoot during the approach that a poor field has been selected—one that would obviously result in disaster if a landing were to be • Premature flap extension/landing gear extension made—and there is a more advantageous field within gliding distance, a change to the better field should be permitted. • Use of throttle to increase the glide instead of merely The hazards involved in these last-minute decisions, such clearing the engine as excessive maneuvering at very low altitudes, must be thoroughly explained by the instructor. • Forcing the airplane onto the runway in order to avoid overshooting the designated landing spot Instructors must stress slipping the airplane, using flaps, varying the position of the base leg, and varying the turn Emergency Approaches and Landings onto final approach as ways of correcting for misjudgment (Simulated) of altitude and glide angle. During dual training flights, the instructor should give Eagerness to get down is one of the most common faults of simulated emergency landings by retarding the throttle and inexperienced pilots during simulated emergency landings. calling “simulated emergency landing.” The objective of They forget about speed and arrive at the edge of the field these simulated emergency landings is to develop a pilot’s with too much speed to permit a safe landing. Too much accuracy, judgment, planning, procedures, and confidence speed is just as dangerous as too little; it results in excessive when little or no power is available. A simulated emergency floating and overshooting the desired landing spot. Instructors landing may be given with the airplane in any configuration. must stress during their instruction that pilots cannot dive at When the instructor calls “simulated emergency landing,” a field and expect to land on it. immediately establish a glide attitude and ensure that the During all simulated emergency landings, keep the engine flaps and landing gear are in the proper configuration for the warm and cleared. During a simulated emergency landing, existing situation. When the proper glide speed is attained, either the instructor or the pilot should have complete the nose can then be lowered and the airplane trimmed to control of the throttle. There must be no doubt as to who has maintain that speed. control since many near accidents have occurred from such misunderstandings. A constant gliding speed is maintained because variations of gliding speed nullify all attempts at accuracy in judgment of gliding distance and the landing spot. The many variables, such as altitude, obstruction, wind direction, landing direction, landing surface and gradient, and landing distance requirements of the airplane, determines the pattern and approach procedures to use. Use any combination of normal gliding maneuvers, from Every simulated emergency landing approach is terminated wings level to spirals to eventually arrive at the normal key as soon as it can be determined whether a safe landing could position at a normal traffic pattern altitude for the selected have been made. In no case should it be continued to a point 8-26

Spiral over landing field WIND Retract flaps Base key point lower flaps Figure 8-29. Remain over intended landing area. where it creates an undue hazard or an annoyance to persons actual emergency landings have been made and later found or property on the ground. to be the result of the fuel selector valve being positioned to an empty tank while the other tank had plenty of fuel. It may In addition to flying the airplane from the point of simulated be wise to change the position of the fuel selector valve even engine failure to where a reasonable safe landing could though the fuel gauge indicates fuel in all tanks because fuel be made, a pilot should also receive instruction on certain gauges can be inaccurate. Many actual emergency landings emergency cockpit procedures. The habit of performing these could have been prevented if the pilots had developed the cockpit procedures must be developed to such an extent that, habit of checking these critical items during flight training when an engine failure actually occurs, a pilot checks the to the extent that it carried over into later flying. critical items that are necessary to get the engine operating again while selecting a field and planning an approach. Instruction in emergency procedures is not limited to Combining the two operations—accomplishing emergency simulated emergency landings caused by power failures. procedures and planning and flying the approach—are Other emergencies associated with the operation of the difficult during the early training in emergency landings. airplane should be explained, demonstrated, and practiced if practicable. Among these emergencies are fire in flight, There are definite steps and procedures to be followed electrical or hydraulic system malfunctions, unexpected in a simulated emergency landing. Although they may severe weather conditions, engine overheating, imminent differ somewhat from the procedures used in an actual fuel exhaustion, and the emergency operation of airplane emergency, they must be learned thoroughly and each step systems and equipment. called out to the instructor. The use of a checklist is strongly recommended. Most airplane manufacturers provide a Faulty Approaches and Landings checklist of the appropriate items. [Figure 8-30] Low Final Approach Critical items to be checked include the position of the When the base leg is too low, insufficient power is used, fuel tank selector, the quantity of fuel in the tank selected, landing flaps are extended prematurely or the velocity of the the fuel pressure gauge to see if the electric fuel pump is wind is misjudged, sufficient altitude is lost, which causes the needed, the position of the mixture control, the position of airplane to be well below the proper final approach path. In the magneto switch, and the use of carburetor heat. Many such a situation, the pilot would have to apply considerable 8-27

1. Airspeed—70 KIAS (flaps UP) 65 KIAS (flaps DOWN) 2. MFuixetlusree—lecIDtoLrEvaClvUeT—-OOFFFF 3. IWgninitgiofnlaspwsi—tchA—S ORFEFQUIRED 4. 5. 6. Master switch—OFF ENG123IN... EACFiFuarsAerbplIueLsreUeedlRet—ocErt7ohD0reUvaKaRtI—lAIvNSeOG—NFBLOITGHHT (RESTART PROCEDURES) MIPgirnximittuioerenr——swIRNiItCcahnH—d LBOOCTKHE(Dor 4. START if propeller is stopped) 5. 6. FEMOER1R.CGAEEirNDsCpeYLeALdA—NN76DD95IIKNKNIIGAAGSSWS((IffTllaaHppOssUUDTPO)EWNNG)INE POWER MFuixetlusree—lecIDtoLrEvaClvUeT—-OOFFFF 2. IWgninitgiofnlaspwsi—tchA—S ORFEFQUIRED (30° RECOMMENDED) 3. 4. MDTBooarauosktcresehr—sds—oUwwANitncPL—hPA—SLTYLCOIHGFHFEHPATRVLIOYILRYTATIOL 5. 6. TOUCHDOWN 7. LOW 8. 9. PRECAUTIONARY LANDING WITH ENGINE POWER Figure 8-30. Sample emergency checklist. power to fly the airplane (at an excessively low altitude) up to while lowering the nose simultaneously to maintain approach the runway threshold. When it is realized the runway cannot airspeed and steepen the approach path. [Figure 8-32] When be reached unless appropriate action is taken, power must be the proper approach path is intercepted, adjust the power as applied immediately to maintain the airspeed while the pitch required to maintain a stabilized approach. When steepening attitude is raised to increase lift and stop the descent. When the approach path, care must be taken that the descent does the proper approach path has been intercepted, the correct not result in an excessively high sink rate. If a high sink approach attitude is reestablished and the power reduced rate is continued close to the surface, it may be difficult to and a stabilized approach maintained. [Figure 8-31] Do slow to a proper rate prior to ground contact. Any sink rate not increase the pitch attitude without increasing the power in excess of 800–1,000 feet per minute (fpm) is considered because the airplane decelerates rapidly and may approach the excessive. A go-around should be initiated if the sink rate critical AOA and stall. Do not retract the flaps; this suddenly becomes excessive. decreases lift and causes the airplane to sink more rapidly. If there is any doubt about the approach being safely completed, Slow Final Approach it is advisable to execute an immediate go-around. On the final approach, when the airplane is flown at a slower than normal airspeed, the pilot’s judgment of the rate of sink High Final Approach (descent) and the height of round out is difficult. During an When the final approach is too high, lower the flaps as excessively slow approach, the wing is operating near the required. Further reduction in power may be necessary, critical AOA and, depending on the pitch attitude changes 8-28

Intercept normal glidepath, resume normal approach Normal approach path Add power nose up hold altitude 2 1 34 Wrong (dragging it in with high power/high pitch altitude) Figure 8-31. Right and wrong methods of correction for low final approach. and control usage, the airplane may stall or sink rapidly, throttle so the additional thrust and lift are removed and the contacting the ground with a hard impact. airplane remains on the ground. Whenever a slow speed approach is noted, apply power to High Round Out accelerate the airplane and increase the lift to reduce the sink rate and to prevent a stall. This is done while still at a high Sometimes when the airplane appears to temporarily stop enough altitude to reestablish the correct approach airspeed moving downward, the round out has been made too rapidly and attitude. If too slow and too low, it is best to execute a and the airplane is flying level, too high above the runway. go-around. Continuing the round out further reduces the airspeed and increases the AOA to the critical angle. This results in the Use of Power airplane stalling and dropping hard onto the runway. To Power can be used effectively during the approach and round prevent this, the pitch attitude is held constant until the out to compensate for errors in judgment. Power is added airplane decelerates enough to again start descending. Then to accelerate the airplane to increase lift without increasing the round out is continued to establish the proper landing the AOA and the descent slowed to an acceptable rate. If attitude. This procedure is only used when there is adequate the proper landing attitude is attained and the airplane is airspeed. It may be necessary to add a slight amount of power only slightly high, the landing attitude is held constant and to keep the airspeed from decreasing excessively and to avoid sufficient power applied to help ease the airplane onto the losing lift too rapidly. ground. After the airplane has touched down, close the No flaps Full flaps Increased rate of descent Steeper descent angle 34 Figure 8-32. Change in glidepath and increase in descent rate for high final approach. 8-29

Although back-elevator pressure may be relaxed slightly, If the round out is late, the nose wheel may strike the runway the nose should not be lowered to make the airplane descend first, causing the nose to bounce upward. Do not attempt to when fairly close to the runway unless some power is added force the airplane back onto the ground; execute a go-around momentarily. The momentary decrease in lift that results from immediately. lowering the nose and decreasing the AOA might cause the airplane to contact the ground with the nose wheel first and Floating During Round Out result in the nose wheel collapsing. If the airspeed on final approach is excessive, it usually results in the airplane floating. [Figure 8-34] Before touchdown can When the proper landing attitude is attained, the airplane is be made, the airplane may be well past the desired landing approaching a stall because the airspeed is decreasing and point and the available runway may be insufficient. When the critical AOA is being approached, even though the pitch diving the airplane on final approach to land at the proper attitude is no longer being increased. [Figure 8-33] point, there is an appreciable increase in airspeed. The proper touchdown attitude cannot be established without producing It is recommended that a go-around be executed any time it an excessive AOA and lift. This causes the airplane to gain appears the nose must be lowered significantly or that the altitude or balloon. landing is in any other way uncertain. Any time the airplane floats, judgment of speed, height, Late or Rapid Round Out and rate of sink must be especially acute. The pilot must Starting the round out too late or pulling the elevator control smoothly and gradually adjust the pitch attitude as the back too rapidly to prevent the airplane from touching down airplane decelerates to touchdown speed and starts to settle, prematurely can impose a heavy load factor on the wing and so the proper landing attitude is attained at the moment of cause an accelerated stall. touchdown. The slightest error in judgment and timing results in either ballooning or bouncing. Suddenly increasing the AOA and stalling the airplane during a round out is a dangerous situation since it may cause the The recovery from floating is dependent upon the amount of airplane to land extremely hard on the main landing gear floating and the effect of any crosswind, as well as the amount and then bounce back into the air. As the airplane contacts of runway remaining. Since prolonged floating utilizes the ground, the tail is forced down very rapidly by the back- considerable runway length, it must be avoided especially on elevator pressure and by inertia acting downward on the tail. short runways or in strong crosswinds. If a landing cannot be made on the first third of the runway, or the airplane drifts Recovery from this situation requires prompt and positive sideways, execute a go-around. application of power prior to occurrence of the stall. This may be followed by a normal landing if sufficient runway Ballooning During Round Out is available—otherwise the pilot should execute a go- If the pilot misjudges the rate of sink during a landing and around immediately. thinks the airplane is descending faster than it should, there is a tendency to increase the pitch attitude and AOA too rapidly. 34 Figure 8-33. Rounding out too high. 8-30

Figure 8-34. Floating during roundout. 34 34 This not only stops the descent, but actually starts the airplane Power must be applied before the airplane enters a stalled climbing. This climbing during the round out is known as condition. ballooning. [Figure 8-35] Ballooning is dangerous because the height above the ground is increasing and the airplane is The pilot must be extremely cautious of ballooning when rapidly approaching a stalled condition. The altitude gained there is a crosswind present because the crosswind correction in each instance depends on the airspeed or the speed with may be inadvertently released or it may become inadequate. which the pitch attitude is increased. Because of the lower airspeed after ballooning, the crosswind affects the airplane more. Consequently, the wing has to be Depending on the severity of ballooning, the use of throttle is lowered even further to compensate for the increased drift. It helpful in cushioning the landing. By adding power, thrust is is imperative that the pilot makes certain that the appropriate increased to keep the airspeed from decelerating too rapidly wing is down and that directional control is maintained with and the wings from suddenly losing lift, but throttle must opposite rudder. If there is any doubt, or the airplane starts be closed immediately after touchdown. Remember that to drift, execute a go-around. torque is created as power is applied, and it is necessary to use rudder pressure to keep the airplane straight as it settles Bouncing During Touchdown onto the runway. When the airplane contacts the ground with a sharp impact as the result of an improper attitude or an excessive rate of sink, When ballooning is excessive, it is best to execute a go- it tends to bounce back into the air. Though the airplane’s tires around immediately; do not attempt to salvage the landing. and shock struts provide some springing action, the airplane Figure 8-35. Ballooning during roundout. 8-31

does not bounce like a rubber ball. Instead, it rebounds into correction. When one main wheel of the airplane strikes the air because the wing’s AOA was abruptly increased, the runway, the other wheel touches down immediately producing a sudden addition of lift. [Figure 8-36] afterwards, and the wings becomes level. Then, with no crosswind correction as the airplane bounces, the wind causes The abrupt change in AOA is the result of inertia instantly the airplane to roll with the wind, thus exposing even more forcing the airplane’s tail downward when the main wheels surface to the crosswind and drifting the airplane more rapidly. contact the ground sharply. The severity of the bounce depends on the airspeed at the moment of contact and the When a bounce is severe, the safest procedure is to execute degree to which the AOA or pitch attitude was increased. a go-around immediately. Do not attempt to salvage the landing. Apply full power while simultaneously maintaining Since a bounce occurs when the airplane makes contact with directional control and lowering the nose to a safe climb the ground before the proper touchdown attitude is attained, attitude. The go-around procedure should be continued even it is almost invariably accompanied by the application of though the airplane may descend and another bounce may be excessive back-elevator pressure. This is usually the result encountered. It is extremely foolish to attempt a landing from of the pilot realizing too late that the airplane is not in the a bad bounce since airspeed diminishes very rapidly in the proper attitude and attempting to establish it just as the second nose-high attitude, and a stall may occur before a subsequent touchdown occurs. touchdown could be made. The corrective action for a bounce is the same as for Porpoising ballooning and similarly depends on its severity. When it is very slight and there is no extreme change in the airplane’s In a bounced landing that is improperly recovered, the airplane pitch attitude, a follow-up landing may be executed by comes in nose first initiating a series of motions that imitate applying sufficient power to cushion the subsequent the jumps and dives of a porpoise. [Figure 8-37] The problem touchdown and smoothly adjusting the pitch to the proper is improper airplane attitude at touchdown, sometimes caused touchdown attitude. by inattention, not knowing where the ground is, miss- trimming or forcing the airplane onto the runway. In the event a very slight bounce is encountered while landing Ground effect decreases elevator control effectiveness and with a crosswind, crosswind correction must be maintained increases the effort required to raise the nose. Not enough while the next touchdown is made. Remember that since elevator or stabilator trim can result in a nose low contact the subsequent touchdown is made at a slower airspeed, the with the runway and a porpoise develops. upwind wing has to be lowered even further to compensate for drift. Porpoising can also be caused by improper airspeed control. Usually, if an approach is too fast, the airplane floats and the Extreme caution and alertness must be exercised any time a pilot tries to force it on the runway when the airplane still bounce occurs, but particularly when there is a crosswind. wants to fly. A gust of wind, a bump in the runway, or even a Inexperienced pilots almost invariably release the crosswind slight tug on the control wheel sends the airplane aloft again. Decreasing angle of attack Normal angle of attack Rapid increase in angle of attack Small angle of attack 34 Figure 8-36. Bouncing during touchdown. 8-32

Decreasing angle of attack Normal angle Decreasing angle of attack of attack Rapid increase in Normal angle of attack Rapid increase in angle of attack angle of attack 34 Figure 8-37. Porpoising. The corrective action for a porpoise is the same as for a the proper speed, and gently lowers the nose wheel while bounce and similarly depends on its severity. When it is very losing speed on rollout. If the pilot decides to stay on the slight and there is no extreme change in the airplane’s pitch ground rather than attempt a go-around or if directional attitude, a follow-up landing may be executed by applying control is lost, close the throttle and adjust the pitch attitude sufficient power to cushion the subsequent touchdown and smoothly but firmly to the proper landing attitude. smoothly adjusting the pitch to the proper touchdown attitude. Hard Landing When a porpoise is severe, the safest procedure is to execute When the airplane contacts the ground during landings, its a go-around immediately. In a severe porpoise, the airplane’s vertical speed is instantly reduced to zero. Unless provisions pitch oscillations can become progressively worse until the are made to slow this vertical speed and cushion the impact airplane strikes the runway nose first with sufficient force to of touchdown, the force of contact with the ground may be collapse the nose gear. Attempts to correct a severe porpoise so great it could cause structural damage to the airplane. with flight control and power inputs is most likely untimely and out of sequence with the oscillations and only make the The purpose of pneumatic tires, shock absorbing landing situation worse. Do not attempt to salvage the landing. Apply gear, and other devices is to cushion the impact and to full power while simultaneously maintaining directional increase the time in which the airplane’s vertical descent is control and lowering the nose to a safe climb attitude. stopped. The importance of this cushion may be understood from the computation that a 6-inch free fall on landing is Wheel Barrowing roughly equal to a 340 fpm descent. Within a fraction of a When a pilot permits the airplane weight to become second, the airplane must be slowed from this rate of vertical concentrated about the nose wheel during the takeoff or descent to zero without damage. landing roll, a condition known as wheel barrowing occurs. Wheel barrowing may cause loss of directional control During this time, the landing gear, together with some aid during the landing roll because braking action is ineffective, from the lift of the wings, must supply whatever force is and the airplane tends to swerve or pivot on the nose wheel, needed to counteract the force of the airplane’s inertia and particularly in crosswind conditions. One of the most weight. The lift decreases rapidly as the airplane’s forward common causes of wheel barrowing during the landing roll speed is decreased, and the force on the landing gear increases is a simultaneous touchdown of the main and nose wheel by the impact of touchdown. When the descent stops, the with excessive speed, followed by application of forward lift is practically zero, leaving the landing gear alone to pressure on the elevator control. Usually, the situation can carry both the airplane’s weight and inertia force. The load be corrected by smoothly applying back-elevator pressure. imposed at the instant of touchdown may easily be three or four times the actual weight of the airplane depending on the If wheel barrowing is encountered and runway and other severity of contact. conditions permit, it is advisable to promptly initiate a go- around. Wheel barrowing does not occur if the pilot achieves and maintains the correct landing attitude, touches down at 8-33

Touchdown in a Drift or Crab swerve tends to make the airplane ground loop, whether it is a tailwheel-type or nose-wheel type. [Figure 8-39] At times, it is necessary to correct for wind drift by crabbing on the final approach. If the round out and touchdown are Nose-wheel type airplanes are somewhat less prone to made while the airplane is drifting or in a crab, it contacts ground loop than tailwheel-type airplanes. Since the center the ground while moving sideways. This imposes extreme of gravity (CG) is located forward of the main landing gear side loads on the landing gear and, if severe enough, may cause structural failure. The most effective method to prevent drift is the wing-low Airplane tips and swerves method. This technique keeps the longitudinal axis of the airplane aligned with both the runway and the direction of motion throughout the approach and touchdown. There are three factors that cause the longitudinal axis and the direction of motion to be misaligned during touchdown: drifting, crabbing, or a combination of both. If the pilot does not take adequate corrective action to avoid CG continues moving in Wind drift during a crosswind landing, the main wheels’ tire tread same direction of drift offers resistance to the airplane’s sideward movement in Touchdown respect to the ground. Consequently, any sidewise velocity of the airplane is abruptly decelerated, resulting in the aircraft Roundout being shifted to the right due to the inertia force which is shown in Figure 8-38. This creates a moment around the Roundout main wheel when it contacts the ground, tending to overturn or tip the airplane. If the windward wingtip is raised by the action of this moment, all the weight and shock of landing is borne by one main wheel. This could cause structural damage. Not only are the same factors present that are attempting to raise a wing, but the crosswind is also acting on the fuselage surface behind the main wheels, tending to yaw (weathervane) the airplane into the wind. This often results in a ground loop. Ground Loop A ground loop is an uncontrolled turn during ground operation that may occur while taxiing or taking off, but especially during the after-landing roll. Drift or weathervaning does not always cause a ground loop, although these things may cause the initial swerve. Careless use of the rudder, an uneven ground surface, or a soft spot that retards one main wheel of the airplane may also cause a swerve. In any case, the initial Wind Center of gravity Wind force Inertia force Weight Force resisting side motion Figure 8-38. Drifting during touchdown. Figure 8-39. Start of a ground loop. 8-34

on these airplanes, any time a swerve develops, centrifugal serious adverse effects on ground controllability and force acting on the CG tends to stop the swerving action. braking efficiency. The three basic types of hydroplaning are dynamic hydroplaning, reverted rubber hydroplaning, If the airplane touches down while drifting or in a crab, and viscous hydroplaning. Any one of the three can render apply aileron toward the high wing and stop the swerve with an airplane partially or totally uncontrollable anytime during the rudder. Brakes are used to correct for turns or swerves the landing roll. only when the rudder is inadequate. Exercise caution when applying corrective brake action because it is very easy to Dynamic Hydroplaning over control and aggravate the situation. Dynamic hydroplaning is a relatively high-speed phenomenon that occurs when there is a film of water on the runway that If brakes are used, sufficient brake is applied on the low-wing is at least one-tenth of an inch deep. As the speed of the wheel (outside of the turn) to stop the swerve. When the wings airplane and the depth of the water increase, the water layer are approximately level, the new direction must be maintained builds up an increasing resistance to displacement, resulting until the airplane has slowed to taxi speed or has stopped. in the formation of a wedge of water beneath the tire. At some speed, termed the hydroplaning speed (Vp), the water In nose-wheel airplanes, a ground loop is almost always a pressure equals the weight of the airplane, and the tire is lifted result of wheel barrowing. A pilot must be aware that even off the runway surface. In this condition, the tires no longer though the nose-wheel type airplane is less prone than the contribute to directional control and braking action is nil. tailwheel-type airplane, virtually every type of airplane, including large multi-engine airplanes, can be made to ground Dynamic hydroplaning is related to tire inflation pressure. Data loop when sufficiently mishandled. obtained during hydroplaning tests have shown the minimum dynamic hydroplaning speed (Vp) of a tire to be 8.6 times Wing Rising After Touchdown the square root of the tire pressure in pounds per square inch When landing in a crosswind, there may be instances when (PSI). For an airplane with a main tire pressure of 24 pounds, a wing rises during the after-landing roll. This may occur the calculated hydroplaning speed would be approximately whether or not there is a loss of directional control, depending 42 knots. It is important to note that the calculated speed on the amount of crosswind and the degree of corrective action. referred to above is for the start of dynamic hydroplaning. Once hydroplaning has started, it may persist to a significantly Any time an airplane is rolling on the ground in a crosswind slower speed depending on the type being experienced. condition, the upwind wing is receiving a greater force from the wind than the downwind wing. This causes a lift Reverted Rubber Hydroplaning differential. Also, as the upwind wing rises, there is an Reverted rubber (steam) hydroplaning occurs during heavy increase in the AOA, which increases lift on the upwind braking that results in a prolonged locked-wheel skid. Only a wing, rolling the airplane downwind. thin film of water on the runway is required to facilitate this type of hydroplaning. The tire skidding generates enough heat When the effects of these two factors are great enough, the to cause the rubber in contact with the runway to revert to upwind wing may rise even though directional control is its original uncured state. The reverted rubber acts as a seal maintained. If no correction is applied, it is possible that the between the tire and the runway and delays water exit from upwind wing rises sufficiently to cause the downwind wing the tire footprint area. The water heats and is converted to to strike the ground. steam, which supports the tire off the runway. In the event a wing starts to rise during the landing roll, Reverted rubber hydroplaning frequently follows an immediately apply more aileron pressure toward the high encounter with dynamic hydroplaning, during which time the wing and continue to maintain direction. The sooner the pilot may have the brakes locked in an attempt to slow the aileron control is applied, the more effective it is. The further airplane. Eventually the airplane slows enough to where the a wing is allowed to rise before taking corrective action, the tires make contact with the runway surface and the airplane more airplane surface is exposed to the force of the crosswind. begins to skid. The remedy for this type of hydroplane is This diminishes the effectiveness of the aileron. to release the brakes and allow the wheels to spin up and apply moderate braking. Reverted rubber hydroplaning is Hydroplaning insidious in that the pilot may not know when it begins, and it can persist to very slow ground speeds (20 knots or less). Hydroplaning is a condition that can exist when an airplane has landed on a runway surface contaminated with standing water, slush, and/or wet snow. Hydroplaning can have 8-35

Viscous Hydroplaning Viscous hydroplaning is due to the viscous properties of water. A thin film of fluid no more than one thousandth of an inch in depth is all that is needed. The tire cannot penetrate the fluid and the tire rolls on top of the film. This can occur at a much lower speed than dynamic hydroplane, but requires a smooth or smooth acting surface, such as asphalt or a touchdown area coated with the accumulated rubber of past landings. Such a surface can have the same friction coefficient as wet ice. When confronted with the possibility of hydroplaning, it is best to land on a grooved runway (if available). Touchdown speed should be as slow as possible consistent with safety. After the nose wheel is lowered to the runway, moderate braking is applied. If deceleration is not detected and hydroplaning is suspected, raise the nose and use aerodynamic drag to decelerate to a point where the brakes do become effective. Proper braking technique is essential. The brakes are applied firmly until reaching a point just short of a skid. At the first sign of a skid, release brake pressure and allow the wheels to spin up. Directional control is maintained as far as possible with the rudder. Remember that in a crosswind, if hydroplaning occurs, the crosswind causes the airplane to simultaneously weathervane into the wind, as well as slide downwind. Chapter Summary Accident statistics show that a pilot is at most risk for an accident during the approach and landing than any other phase of a flight. There are many factors that contribute to accidents in this phase, but an overwhelming percentage of accidents are caused from pilot’s lack of proficiency. This chapter presents procedures that, when learned and practiced, are a key to attaining proficiency. Additional information on aerodynamics, airplane performance, and other aspects affecting approaches and landings can be found in the Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25, as revised). For information concerning risk assessment as a means of preventing accidents, refer to the Risk Management Handbook (FAA-H-8083-2). Both of these publications are available at www.faa.gov/library/manuals/aviation. 8-36

PChapeterr9formance Maneuvers Introduction Flight maneuvers that are initially taught to pilots are designed to be basic and relatively simple: straight-and-level, turns, climbs and descents. However, as a pilot continues through their flight training, additional maneuvers are needed to develop beyond the fundamentals. Performance maneuvers are intended to enhance a pilot’s proficiency in flight control application, maneuver planning, situational awareness, and division of attention. To further that intent, performance maneuvers are generally designed so that the application of flight control pressures, attitudes, airspeeds, and orientations are constantly changing throughout the maneuver. 9-1

Performance maneuvers also allow for an effective attention between flight control application, and the constant assessment of a pilot’s ability to apply the fundamentals; need to scan for hazards. [Figure 9-1] weakness in executing performance maneuvers is likely due to a pilot’s lack of understanding or a deficiency of When steep turns are first demonstrated, the pilot will be fundamental skills. It is advisable that performance maneuver in an unfamiliar environment when compared to what training should not take place until sufficient competency was previously experienced in shallow bank angled turns; in the fundamentals is consistently demonstrated by the however, the fundamental concepts of turns remain the same pilot. Further, initial training for performance maneuvers in the execution of steep turns. When performing steep turns, should always begin with a detailed ground lesson for each pilots will be exposed to higher load factors, the airplane’s maneuver, so that the technicalities are understood prior to inherent overbanking tendency, the loss of vertical component flight. In addition, performance maneuver training should be of lift when the wings are steeply banked, the need for segmented into comprehensible building blocks of instruction substantial pitch control pressures, and the need for additional so as to allow the pilot an appropriate level of repetition to power to maintain altitude and airspeed during the turn. develop the required skills. As discussed in previous chapters, when an airplane is banked, Performance maneuvers, once grasped by the pilot, are very the total lift is comprised of a vertical component of lift and a satisfying and rewarding. As the pilot develops skills in horizontal component of lift. In order to not lose altitude, the executing performance maneuvers, they may likely see an pilot must increase the wing’s angle of attack (AOA) to ensure increased smoothness in their flight control application and a that the vertical component of lift is sufficient to maintain higher ability to sense the airplane’s attitude and orientation altitude. In a steep turn, the pilot will need to increase pitch without significant conscious effort. with elevator back pressures that are greater than what has been previously utilized. Total lift must increase substantially Steep Turns to balance the load factor or G-force (G). The load factor is the vector resultant of gravity and centrifugal force. For example, Steep turns consist of single to multiple 360° to 720° turns, in in a level altitude, 45° banked turn, the resulting load factor either or both directions, using a bank angle between 45° to is 1.4; in a level altitude, 60° banked turn, the resulting load 60°. The objective of the steep turn is to develop a pilot’s skill factor is 2.0. To put this in perspective, with a load factor of in flight control smoothness and coordination, an awareness 2.0, the effective weight of the aircraft will double. Pilots of the airplane’s orientation to outside references, division of WIND Figure 9-1. Steep turns. 9-2

should realize load factors increase dramatically beyond to hold the airplane in level flight—to maintain altitude. 60°. Most general aviation airplanes are designed for a load Pilots should keep in mind that as the AOA increases, so limit of 3.8Gs. Regardless of the airspeed or what airplane is does drag. Consequently, power must be added to maintain involved, for a given bank angle in a level altitude turn, the altitude and airspeed. same load factor will always be produced. A light, general aviation airplane in a level altitude, 45° angle of bank turn Steep turns can be conducted more easily by the use of will experience a load factor of 1.4 just as a large commercial elevator trim and power as the maneuver is entered. In many airliner will in the same level altitude, 45° angle of bank turn. light general aviation airplanes, as the bank angle transitions from medium to steep, increasing elevator up trim and adding Because of the higher load factors, steep turns should be a small increase in engine power minimizes control pressure performed at an airspeed that does not exceed the airplane’s requirements. Pilots must not forget to remove both the trim design maneuvering speed (VA) or the manufacturer’s and power inputs as the maneuver is completed. recommended speed. Maximum turning performance is accomplished when an airplane has both a fast rate of turn and To maintain bank angle, altitude, as well as orientation, minimum radius of turn, which is effected by both airspeed requires an awareness of the relative position of the horizon and angle of bank. Each airplane’s turning performance to the nose and the wings. The pilot who references the is limited by structural and aerodynamic design, as well aircraft’s attitude by observing only the nose will have as available power. The airplane’s limiting load factor difficulty maintaining altitude. A pilot who observes both determines the maximum bank angle that can be maintained the nose and the wings relative to the horizon is likely able in level flight without exceeding the airplane’s structural to maintain altitude within performance standards. Altitude limitations or stalling. As the load factor increases, so does deviations are primary errors exhibited in the execution of the stalling speed. For example, if an airplane stalls in level steep turns. If the altitude does increase or decrease, changing flight at 50 knots, it will stall at 60 knots in a level altitude, elevator back pressure could be used to alter the altitude; 45° banked turn and at 70 knots in a level altitude, 60° banked however, a more effective method is a slight increase or turn. Stalling speed increases at the square root of the load decrease in bank angle to control small altitude deviations. If factor. As the bank angle increases in level flight, the margin altitude is decreasing, reducing the bank angle a few degrees between stalling speed and maneuvering speed decreases—an helps recover or stop the altitude loss trend; also, if altitude important concept for a pilot to remain cognizant. is increasing, increasing the bank angle a few degrees helps recover or stop the altitude increase trend—all bank angle In addition to the increased load factors, the airplane will changes should be accomplished with coordinated use of exhibit what is called “overbanking tendency.” Recall from a aileron and rudder. previous chapter on the discussion of overbanking tendency. In most flight maneuvers, bank angles are shallow enough The rollout from the steep turn should be timed so that the that the airplane exhibits positive or neutral stability about wings reach level flight when the airplane is on heading from the longitudinal axis; however, as bank angles steepen, which the maneuver was started. A good rule of thumb is to the airplane will exhibit the behavior to continue rolling begin the rollout at ½ the number of degrees of bank prior in the direction of the bank unless deliberate and opposite to reaching the terminating heading. For example, if a right aileron pressure is held against the bank. Also, pilots should steep turn was begun on a heading of 270° and if the bank be mindful of the various left turning tendencies, such as angle is 60°, the pilot should begin the rollout 30° prior or at P-factor, which requires effective rudder aileron coordination. a heading of 240°. While the rollout is being made, elevator back pressure, trim, and power should be gradually reduced, Before starting any practice maneuver, the pilot must ensure as necessary, to maintain the altitude and airspeed. that the area is clear of air traffic and other hazards. Further, distant references such as a mountain peak or road should be Common errors when performing steep turns are: chosen to allow the pilot to assess when to begin rollout from the turn. After establishing the manufacturer’s recommended • Not clearing the area entry speed or the design maneuvering speed, the airplane should be smoothly rolled into the desired bank angle • Inadequate pitch control on entry or rollout somewhere between 45° to 60°. As the bank angle is being established, generally prior to 30° of bank, elevator back • Gaining altitude or losing altitude pressure should be smoothly applied to increase the AOA. After the selected bank angle has been reached, the pilot will • Failure to maintain constant bank angle find that considerable force is required on the elevator control • Poor flight control coordination • Ineffective use of trim 9-3

• Ineffective use of power is established. Once the proper airspeed is attained, the pitch should be lowered and the airplane rolled to the desired bank • Inadequate airspeed control angle as the reference point is reached. The steepest bank should not exceed 60°. The gliding spiral should be a turn • Becoming disoriented of constant radius while maintaining the airplane’s position to the reference. This can only be accomplished by proper • Performing by reference to the flight instrument rather correction for wind drift by steepening the bank on downwind than visual references headings and shallowing the bank on upwind headings, just as in the maneuver, turns around a point. During the steep • Failure to scan for other traffic during the maneuver spiral, the pilot must continually correct for any changes in wind direction and velocity to maintain a constant radius. • Attempts to start recovery prematurely Operating the engine at idle speed for any prolonged period • Failure to stop the turn on designated heading during the glide may result in excessive engine cooling, spark plug fouling, or carburetor ice. To assist in avoiding these Steep Spiral issues, the throttle should be periodically advanced to normal cruise power and sustained for a few seconds. If equipped, The objective of the steep spiral is to provide a flight monitoring cylinder head temperatures provides a pilot with maneuver for rapidly dissipating substantial amounts of additional information on engine cooling. When advancing altitude while remaining over a selected spot. This maneuver the throttle, the pitch attitude must be adjusted to maintain a is especially effective for emergency descents or landings. constant airspeed and, preferably, this should be done when A steep spiral is a gliding turn where the pilot maintains headed into the wind. a constant radius around a surface-based reference point while rapidly descending—similar to the turns around a Maintaining a constant airspeed throughout the maneuver point maneuver. Sufficient altitude must be gained prior is an important skill for a pilot to develop. This is necessary to practicing the maneuver so that at least three 360° turns because the airspeed tends to fluctuate as the bank angle is are completed. [Figure 9-2] The maneuver should not be changed throughout the maneuver. The pilot should anticipate allowed to continue below 1,500 feet above ground level pitch corrections as the bank angle is varied throughout the (AGL) unless an actual emergency exists. The steep spiral is initiated by properly clearing the airspace for air traffic and hazards. In general, the throttle is closed to idle, carburetor heat is applied if equipped, and gliding speed Figure 9-2. Steep spiral. 9-4

maneuver. During practice of the maneuver, the pilot should Chandelle execute three turns and roll out toward a definite object or on a specific heading. During rollout, the smooth and accurate A chandelle is a maximum performance, 180° climbing turn application of the flight controls allow the airplane to recover that begins from approximately straight-and-level flight to a wing’s level glide with no change in airspeed. Recovering and concludes with the airplane in a wings-level, nose-high to normal cruise flight would proceed after the establishment attitude just above stall speed. [Figure 9-3] The goal is of a wing’s level glide. to gain the most altitude possible for a given bank angle and power setting; however, the standard used to judge Common errors when performing steep spirals are: the maneuver is not the amount of altitude gained, but by the pilot’s proficiency as it pertains to maximizing climb • Not clearing the area performance for the power and bank selected, as well as the skill demonstrated. • Inadequate pitch control on entry or rollout A chandelle is best described in two specific phases: the • Gaining altitude first 90° of turn and the second 90° of turn. The first 90° of turn is described as constant bank and changing pitch; and • Not correcting the bank angle to compensate for wind the second 90° as constant pitch and changing bank. During the first 90°, the pilot will set the bank angle, increase power • Poor flight control coordination and pitch at a rate so that maximum pitch-up is set at the completion of the first 90°. If the pitch is not correct, the • Ineffective use of trim airplane’s airspeed is either above stall speed or the airplane may aerodynamically stall prior to the completion of the • Inadequate airspeed control maneuver. Starting at the 90° point, the pilot begins a slow and coordinated constant rate rollout so as to have the wings • Becoming disoriented level when the airplane is at the 180° point while maintaining the constant pitch attitude set in the first 90°. If the rate of • Performing by reference to the flight instrument rather rollout is too rapid or sluggish, the airplane either does not than visual references • Not scanning for other traffic during the maneuver • Not completing the turn on designated heading or reference 1. Complete rollout to wings level at 180° point 2. Airspeed cVoSo1rdinated 3. Maintain flight 1. Continue smooth rollout 1. Maintain 30° bank until 4. Hold airspeed without stalling 2. Hold pitch this point and then begin 3. Maintain coordinated flight gradual rollout. E D 2. Maximum pitch should be reached. No further changes in pitch A C 1. Clear area B 2. VA or manufacturer’s 1. Roll into 30° bank recommended speed 2. Neuralize ailerons 3. No lower than 1,500 3. Begin increasing pitch feet AGL toward climbing attitude 4. Trim 4. Apply full power without exceeding limits 5. Increase rudder pressure Figure 9-3. Chandelle. 9-5

complete or exceeds the 180° turn as the wings come level [Figure 9-3E] Once demonstrated that the airplane is in to the horizon. controlled flight, the pitch attitude may be reduced and the airplane returned to straight-and-level cruise flight. Prior to starting the chandelle, the flaps and landing gear (if retractable) should be in the UP position. The chandelle is Common errors when performing chandelles are: initiated by properly clearing the airspace for air traffic and hazards. The maneuver should be entered from straight-and- • Not clearing the area level flight or a shallow dive at an airspeed recommended by the manufacturer—in most cases this is the airplane’s design • Initial bank is too shallow resulting in a stall maneuvering speed (VA). [Figure 9-3A] After the appropriate entry airspeed has been established, the chandelle is started by • Initial bank is too steep resulting in failure to gain smoothly entering a coordinated turn to the desired angle of maximum performance bank; once the bank angle is established, which is generally 30°, a climbing turn should be started by smoothly applying • Allowing the bank angle to increase after initial elevator back pressure at a constant rate while simultaneously establishment increasing engine power to the recommended setting. In airplanes with a fixed-pitch propeller, the throttle should be set • Not starting the recovery at the 90° point in the turn so as to not exceed rotations per minute (rpm) limitations; in airplanes with constant-speed propellers, power may be set at • Allowing the pitch attitude to increase as the bank is the normal cruise or climb setting as appropriate. [Figure 9-3B] rolled out during the second 90° of turn Since the airspeed is constantly decreasing throughout the • Leveling the wings prior to the 180° point being chandelle, the effects of left turning tendencies, such as reached P-factor, becomes more apparent. As airspeed decreases, right-rudder pressure is progressively increased to ensure that • Pitch attitude is low on recovery resulting in airspeed the airplane remains in coordinated flight. The pilot should well above stall speed maintain coordinated flight by sensing slipping or skidding pressures applied to the controls and by quick glances to the • Application of flight control pressures is not smooth ball in the turn-and-slip or turn coordinator. • Poor flight control coordination At the 90° point, the pilot should begin to smoothly roll out of the bank at a constant rate while maintaining the pitch attitude • Stalling at any point during the maneuver set in the first 90°. While the angle of bank is fixed during the first 90°, recall that as airspeed decreases, the overbanking • Execution of a steep turn instead of a climbing tendency increases. [Figure 9-3C] As a result, proper use of maneuver the ailerons allows the bank to remain at a fixed angle until rollout is begun at the start of the final 90°. As the rollout • Not scanning for other traffic during the maneuver continues, the vertical component of lift increases; therefore, a slight release of elevator back pressure is required to keep • Performing by reference to the flight instrument rather the pitch attitude from increasing. than visual references When the airspeed is slowest, near the completion of the Lazy Eight chandelle, right rudder pressure is significant, especially when rolling out from a left chandelle due to left adverse yaw and The lazy eight is a maneuver that is designed to develop left turning tendencies, such as P-factor. [Figure 9-3D] When the proper coordination of the flight controls across a wide rolling out from a right chandelle, the yawing moment is to range of airspeeds and attitudes. It is the only standard flight the right, which partially cancels some of the left turning training maneuver that, at no time, flight control pressures tendency’s effect. Depending on the airplane, either very are constant. In an attempt to simplify the discussion about little left rudder or a reduction in right rudder pressure is this maneuver, the lazy eight can be loosely described by the required during the rollout from a right chandelle. At the ground reference maneuver, S-turns across the road. Recall completion of 180° of turn, the wings should be leveled to that S-turns across the road are made of opposing 180° the horizon, the airspeed should be just above stall speed, and turns. For example, first a 180° turn to the right, followed the airplane’s pitch high attitude should be held momentarily. immediately by a 180° turn to the left. The lazy eight adds both a climb and descent to each 180° segment. The first 90° is a climb; the second 90° is a descent. [Figure 9-4] To aid in the performance of the lazy eight’s symmetrical climbing/descending turns, prominent reference points must be selected on the natural horizon. The reference points selected should be at 45°, 90°, and 135° from the direction in which the maneuver is started for each 180° turn. With the general concept of climbing and descending turns grasped, specifics of the lazy eight can then be discussed. 9-6

90° point 135° point 1. Bank 30° (approximate) 1. Maximum pitch-down 2. Minimum speed 2. Bank 15° (approximate) 3. Maximum altitude 4. Level pitch attitude D C E B 180° point 1. Level flight 45° point 2. Entry airspeed 1. Maximum pitch-up attitude 3. Altitude same as entry altitude 2. Bank 15° (approximate) Entry 1. Level flight A 2. Maneuvering or cruise speed (whichever is less or manufacturer’s recommended speed) Figure 9-4. Lazy eight. Shown in Figure 9-4A, from level flight a gradual climbing right and left turns; however, additional right rudder pressure turn is begun in the direction of the 45° reference point; the is required when turning or rolling out to the right than left climbing turn should be planned and controlled so that the because left adverse yaw augments with the left yawing maximum pitch-up attitude is reached at the 45° point with P-factor in an attempt to yaw the nose to the left. Correction an approximate bank angle of 15°. [Figure 9-4B] As the pitch is needed to prevent these additive left yawing moments from attitude is raised, the airspeed decreases, which causes the decreasing a right turn’s rate. In contrast, in left climbing rate of turn to increase. As such, the lazy eight must begin turns or rolling to the left, the left yawing P-factor tends to with a slow rate of roll as the combination of increasing cancel the effects of adverse yaw to the right; consequently, pitch and increasing bank may cause the rate of turn to be so less right rudder pressure is required. These concepts can be rapid that the 45° reference point will be reached before the difficult to remember; however, to simplify, rolling right at highest pitch attitude is attained. At the 45° reference point, low airspeeds and high-power settings requires substantial the pitch attitude should be at the maximum pitch-up selected right rudder pressures. for the maneuver while the bank angle is slowly increasing. Beyond the 45° reference point, the pitch-up attitude should At the lazy eight’s 90° reference point, the bank angle should begin to decrease slowly toward the horizon until the 90° also have reached its maximum angle of approximately 30°. reference point is reached where the pitch attitude should [Figure 9-4C] The airspeed should be at its minimum, just be momentarily level. about 5 to 10 knots above stall speed, with the airplane’s pitch attitude passing through level flight. Coordinated flight at this The lazy eight requires substantial skill in coordinating point requires that, in some flight conditions, a slight amount the aileron and rudder; therefore, some discussion about of opposite aileron pressure may be required to prevent the coordination is warranted. As pilots understand, the purpose wings from overbanking while maintaining rudder pressure of the rudder is to maintain coordination; slipping or to cancel the effects of left turning tendencies. skidding is to be avoided. Pilots should remember that since the airspeed is still decreasing as the airplane is climbing; The pilot should not hesitate at the 90° point but should additional right rudder pressure must be applied to counteract continue to maneuver the airplane into a descending turn. left turning tendencies, such as P-factor. As the airspeed The rollout from the bank should proceed slowly while decreases, right rudder pressure must be gradually applied the airplane’s pitch attitude is allowed to decrease. When to counteract yaw at the apex of the lazy eight in both the the airplane has turned 135°, the airplane should be in 9-7

its lowest pitch attitude. [Figure 9-4D] Pilots should Chapter Summary remember that the airplane’s airspeed is increasing as the airplane’s pitch attitude decreases; therefore, to maintain Performance maneuvers are used to develop a pilot’s skills proper coordination will require a decrease in right rudder in coordinating the flight control’s use and effect while pressure. As the airplane approaches the 180° point, it is enhancing the pilot’s ability to divide attention across the necessary to progressively relax rudder and aileron pressure various demands of flight. Performance maneuvers are while simultaneously raising pitch and roll to level flight. also designed to further develop a pilot’s application and As the rollout is being accomplished, the pilot should note correlation of the fundamentals of flight and integrate the amount of turn remaining and adjust the rate of rollout developing skills into advanced maneuvers. Developing and pitch change so that the wings and nose are level at the highly-honed skills in performance maneuvers allows the original airspeed just as the 180° point is reached. pilot to effectively progress toward the mastery of flight. Mastery is developed as the mechanics of flight become Upon arriving at 180° point, a climbing turn should be started a subconscious, rather than a conscious, application of immediately in the opposite direction toward the preselected the flight controls to maneuver the airplane in attitude, reference points to complete the second half of the lazy eight orientation, and position. in the same manner as the first half. [Figure 9-4E] Power should be set so as not to enter the maneuver at an airspeed that would exceed manufacturer’s recommendations, which is generally no greater than VA. Power and bank angle have significant effect on the altitude gained or lost; if excess power is used for a given bank angle, altitude is gained at the completion of the maneuver; however, if insufficient power is used for a given bank angle, altitude is lost. Common errors when performing lazy eights are: • Not clearing the area • Maneuver is not symmetrical across each 180° • Inadequate or improper selection or use of 45°, 90°, 135° references • Ineffective planning • Gain or loss of altitude at each 180° point • Poor control at the top of each climb segment resulting in the pitch rapidly falling through the horizon • Airspeed or bank angle standards not met • Control roughness • Poor flight control coordination • Stalling at any point during the maneuver • Execution of a steep turn instead of a climbing maneuver • Not scanning for other traffic during the maneuver • Performing by reference to the flight instrument rather than visual references 9-8

NightChapter10 Operations Introduction The mechanical operation of an airplane at night is no different than operating the same airplane during the day. The airplane does not know if it is being operated in the dark or bright sunlight. It performs and responds to control inputs by the pilot. The pilot, however, is affected by various aspects of night operations and must take them into consideration during night flight operations. Some are actual physical limitations affecting all pilots while others, such as equipment requirements, procedures, and emergency situations, must also be considered. According to Title 14 of the Code of Federal Regulations (14 CFR) part 1, Definitions and Abbreviations, night is defined as the time between the end of evening civil twilight and the beginning of morning civil twilight. To explain further, morning civil twilight begins when the geometric center of the sun is 6° below the horizon and ends at sunrise. Evening civil twilight begins at sunset and ends when the geometric center of the sun reaches 6° below the horizon. 10-1

For 14 CFR part 61 operations, the term night refers to 1 hour Cones for after sunset and ending 1 hour before sunrise as 14 CFR part • Color 61 explains that between those hours no person may act as • Detail pilot in command (PIC) of an aircraft carrying passengers • Day unless within the preceding 90 days that person has made at least three takeoffs and three landings to a full stop during Rods for that night period. • Gray • Peripheral Night flying operations should not be encouraged or • Day and night attempted except by certificated pilots with knowledge of and experience in the topics discussed in this chapter. Area of best day vision Night Vision Area of best night vision Night blind spot Generally, most pilots are poorly informed about night vision. Human eyes never function as effectively at night as the eyes Area of best night vision of animals with nocturnal habits, but if humans learn how to use their eyes correctly and know their limitations, night vision can be improved significantly. The brain and eyes act as a team for a person to see well; both must be used effectively. Due to the physiology of the eye, limitations on sight are experienced in low light conditions, such as at night. To see at night, the eyes are used differently than during the day. Therefore, it is important to understand the eye’s construction and how the eye is affected by darkness. Innumerable light-sensitive nerves called “cones” and “rods” are located at the back of the eye or retina, a layer upon which all images are focused. These nerves connect to the cells of the optic nerve, which transmits messages directly to the brain. The cones are located in the center of the retina, and the rods are concentrated in a ring around the cones. [Figure 10-1] The function of the cones is to detect color, details, and faraway objects. The rods function when something is seen out of the corner of the eye or peripheral vision. They detect objects, particularly those that are moving, but do not give detail or color—only shades of gray. Both the cones and the rods are used for vision during daylight. Although there is not a clear-cut division of function, the rods Figure 10-1. Rods and cones. make night vision possible. The rods and cones function in daylight and in moonlight, but in the absence of normal light, larger objects as the distance between the pilot and an object the process of night vision is placed almost entirely on the rods. increases. Use of a scanning procedure to permit off-center The rods are distributed in a band around the cones and do not viewing of the object is more effective. Consciously practice lie directly behind the pupils, which makes off-center viewing this scanning procedure to improve night vision. (looking to one side of an object) important during night flight. During daylight, an object can be seen best by looking directly The eye’s adaptation to darkness is another important aspect at it, but at night there is a blind spot in the center of the field of night vision. When a dark room is entered, it is difficult to of vision, the night blind spot. If an object is in this area, it see anything until the eyes become adjusted to the darkness. may not be seen. The size of this blind spot increases as the Almost everyone experiences this when entering a darkened distance between the eye and the object increases as illustrated movie theater. In this process, the pupils of the eyes first in Figure 10-1. Therefore, the night blind spot can hide 10-2

enlarge to receive as much of the available light as possible. • Close one eye when exposed to bright light to help After approximately 5 to 10 minutes, the cones become avoid the blinding effect. adjusted to the dim light and the eyes become approximately 100 times more sensitive to the light than they were before the • Do not wear sunglasses after sunset as this impairs dark room was entered. Much more time, about 30 minutes, is night vision. needed for the rods to become adjusted to darkness, but when they do adjust, they are about 100,000 times more sensitive to • Move the eyes more slowly than in daylight. light than they were in the lighted area. After the adaptation process is complete, much more can be seen, especially if • Blink the eyes if they become blurred. scanning techniques are used correctly. • Concentrate on seeing objects. After the eyes have adapted to the dark, the entire process is reversed when entering a lighted room. The eyes are first • Force the eyes to view off center using scanning dazzled by the brightness, but become completely adjusted techniques. in a very few seconds, thereby losing their adaptation to the dark. Now, if the dark room is re-entered, the eyes again go • Maintain good physical condition. through the long process of adapting to the darkness. • Avoid smoking, drinking, and using drugs that may Before and during night flight, the adaptation process of be harmful. the eyes must be considered. First, adapt to the low level of light and then stay adapted. After the eyes are adapted to the Night Illusions darkness, avoid exposing them for more than one second to any bright white light as that causes temporary blindness. In addition to night vision limitations, night illusions can If exposed to a bright light source, such as search lights and cause confusion and distractions during night flying. The landing lights, remember that each eye adapts to the dark following discussion covers some of the common situations independently. By closing or covering one eye when exposed that cause illusions associated with night flying. to light, some night vision acuity is retained in the closed eye. On a clear night, distant stationary lights can be mistaken Temporary blindness, caused by an unusually bright light, for stars or other aircraft. Cloud layers or even the northern may result in illusions or after images until the eyes recover lights can confuse a pilot and indicate a false visual horizon. from the brightness. The brain creates these illusions Certain geometrical patterns of ground lights, such as a reported by the eyes. This results in misjudging or incorrectly freeway, runway, approach, or even lights on a moving identifying objects, such as mistaking slanted clouds for the train, can cause confusion. Dark nights tend to eliminate horizon or populated areas for a landing field. Vertigo is reference to a visual horizon. As a result, pilots need to rely experienced as a feeling of dizziness and imbalance that can less on outside references at night and more on flight and create or increase illusions. The illusions seem very real and navigation instruments. pilots at every level of experience and skill can be affected. Recognizing that the brain and eyes can play tricks in this Visual autokinesis can occur when staring at a single light manner is the best protection for flying at night. source for several seconds on a dark night. The result is that the light appears to be moving. The autokinesis effect will Good eyesight depends upon physical condition. Fatigue, not occur if the visual field is expanded through scanning colds, vitamin deficiency, alcohol, stimulants, smoking, or techniques. A good scanning procedure reduces the medication can seriously impair vision. Keep these facts in probability of vision becoming fixed on one source of light. mind and take adequate precautions to safeguard night vision. In addition to the principles previously discussed, the following Distractions and problems can result from a flickering light items aid in increasing night vision effectiveness. in the flightdeck, anti-collision light, or other aircraft lights and can cause flicker vertigo. If continuous, the possible • Adapt the eyes to darkness prior to flight and keep physical reactions can be nausea, dizziness, grogginess, them adapted. About 30 minutes is needed to adjust unconsciousness, headaches, or confusion. Try to eliminate the eyes to maximum efficiency after exposure to a any light source causing blinking or flickering problems in bright light. the flightdeck. • If oxygen is available, use it during night flying. Keep A black-hole approach occurs when the landing is made in mind that a significant deterioration in night vision from over water or non-lighted terrain where the runway can occur at cabin altitudes as low as 5,000 feet. lights are the only source of light. Without peripheral visual cues to help, orientation is difficult. The runway can seem out of position (down-sloping or up-sloping) and in the worst case, results in landing short of the runway. If an 10-3

electronic glide slope or visual approach slope indicator the preflight visual inspection of the airplane, and the red (VASI) is available, it should be used. If navigation aids light is used when performing cockpit operations. It is also (NAVAIDs) are unavailable, use the flight instruments to recommended to have a spare set of batteries for the flashlight assist in maintaining orientation and a normal approach. readily available. Anytime position in relation to the runway or altitude is in doubt, execute a go-around. Since the red light is non-glaring, it will not impair night vision. Some pilots prefer two flashlights, one with a white Bright runway and approach lighting systems, especially light for preflight and the other a penlight type with a red where few lights illuminate the surrounding terrain, may light. The latter can be suspended by a string from around the create the illusion of being lower or having less distance to neck to ensure the light is always readily available. One word the runway. In this situation, the tendency is to fly a higher of caution: if a red light is used for reading an aeronautical approach. Also, flying over terrain with only a few lights chart, the red features of the chart will not show up. makes the runway recede or appear farther away. With this situation, the tendency is to fly a lower-than-normal Aeronautical charts are essential for night cross-country approach. If the runway has a city in the distance on higher flight and, if the intended course is near the edge of the chart, terrain, the tendency is to fly a lower-than-normal approach. the adjacent chart should also be available. The lights of A good review of the airfield layout and boundaries before cities and towns can be seen at surprising distances at night, initiating any approach helps maintain a safe approach angle. and if this adjacent chart is not available to identify those landmarks, confusion could result. These checklist items are Illusions created by runway lights result in a variety not just for night flying, they are required for day light flying of problems. Bright lights or bold colors advance the also. Regardless of the equipment used, organization of the runway, making it appear closer. Night landings are further flightdeck eases the burden and enhances safety. Organize complicated by the difficulty of judging distance and the equipment and charts and place them within easy reach prior possibility of confusing approach and runway lights. For to taxiing. example, when a double row of approach lights joins the boundary lights of the runway, there can be confusion where Airplane Equipment and Lighting the approach lights terminate and runway lights begin. Under certain conditions, approach lights can make the aircraft Title 14 of the Code of Federal Regulations (14 CFR) part seem higher in a turn to final, than when its wings are level. 91 specifies the basic minimum airplane equipment that is required for night flight. This equipment includes only basic Pilot Equipment instruments, lights, electrical energy source, and spare fuses. Before beginning a night flight, carefully consider personal The standard instruments required by 14 CFR part 91 for equipment that should be readily available during the flight to instrument flight are a valuable asset for aircraft control at include a flashlight, aeronautical charts and pertinent data for night. Title 14 CFR part 91 specifies that during the period the flight, and a flightdeck checklist containing procedures for from sunset to sunrise operating aircraft are required to have a the following tasks, which can be found in 14 CFR part 91: functioning anti-collision light system, including a flashing or rotating beacon and position lights. The anti-collision lights • Before starting engines however need not be lighted when the pilot in command (PIC) determines that, because of operating conditions, it would be • Before takeoff in the interest of safety to turn the lights off. Airplane position lights are arranged similar to those of boats and ships. A red • Cruise light is positioned on the left wingtip, a green light on the right wingtip, and a white light on the tail. [Figure 10-2] • Before landing This arrangement provides a means to determine the general • After landing direction of movement of other airplanes in flight. If both a red and green light of another aircraft are observed, and • Stopping engines the red light is on the left and the green to the right, the airplane is flying the same direction. Care must be taken not • Emergencies to overtake the other aircraft and maintain clearance. If red were on the right and green to the left, the airplane could be At least one reliable flashlight is recommended as standard on a collision course. equipment on all night flights. A reliable incandescent or light-emitting diode (LED) flashlight able to produce white/ red light and blue for chart reading is preferable. The flash light should be large enough to be easily located in the event it is needed. The white light is used while performing 10-4

It is recommended that prior to a night flight, and particularly a cross-country night flight, that a check of the availability and status of lighting systems at the destination airport is made. This information can be found on aeronautical charts and in the Chart Supplements. The status of each facility can be determined by reviewing pertinent Notices to Airmen (NOTAMs). Figure 10-2. Position lights. Most airports have rotating beacons. The beacon rotates at a constant speed, thus producing a series of light flashes at Landing lights are not only useful for taxi, takeoffs, and regular intervals. These flashes may consist of a white flash landings, but also provide a means by which airplanes can and one or two different colors that are used to identify be seen at night by other pilots. Pilots are encouraged to turn various types of landing areas. For example: on their landing lights when operating within 10 miles of an airport and below 10,000 feet. Operation lights on applies • Lighted civilian land airports—alternating white and to both day and night or in conditions of reduced visibility. green lights This should also be done in areas where flocks of birds may be expected. • Lighted civilian water airports—alternating white and yellow lights Although turning on aircraft lights supports the “see and be seen” concept, do not become complacent about keeping a • Lighted military airports—alternating white and green sharp lookout for other aircraft. Most aircraft lights blend lights, but are differentiated from civil airports by dual in with the stars or the lights of the cities at night and go peaked (two quick) white flashes, then green unnoticed unless a conscious effort is made to distinguish them from other lights. Beacons producing red flashes indicate obstructions or areas considered hazardous to aerial navigation. Steady-burning Airport and Navigation Lighting Aids red lights are used to mark obstructions on or near airports and sometimes to supplement flashing lights on en route The lighting systems used for airports, runways, obstructions, obstructions. High-intensity, flashing white lights are used and other visual aids at night are other important aspects of to mark some supporting structures of overhead transmission night flying. Lighted airports located away from congested lines that stretch across rivers, chasms, and gorges. These areas are identified readily at night by the lights outlining the high-intensity lights are also used to identify tall structures, runways. Airports located near or within large cities are often such as chimneys and towers. difficult to identify as the airport lights tend to blend with the city lights. It is important not to only know the exact location As a result of technological advancements, runway lighting of an airport relative to the city, but also to be able to identify systems have become quite sophisticated to accommodate these airports by the characteristics of their lighting pattern. takeoffs and landings in various weather conditions. However, if flying is limited to VFR only, it is important to Aeronautical lights are designed and installed in a variety be familiar with the basic lighting of runways and taxiways. of colors and configurations, each having its own purpose. Although some lights are used only during low ceiling and The basic runway lighting system consists of two straight visibility conditions, this discussion includes only the lights that parallel lines of runway edge lights defining the lateral limits of are fundamental to visual flight rules (VFR) night operation. the runway. These lights are aviation white, although aviation yellow may be substituted for a distance of 2,000 feet from the far end of the runway to indicate a caution zone. At some airports, the intensity of the runway edge lights can be activated and adjusted by radio control. The control system consists of a 3-step control responsive to 7, 5, and/or 3 microphone clicks. This 3-step control turns on lighting facilities capable of either 3-step, 2-step, or 1-step operation. The 3-step and 2-step lighting facilities can be altered in intensity, while the 1-step cannot. All lighting is illuminated for a period of 15 minutes from the most recent time of activation and may not be extinguished prior to end of the 15-minute period. Suggested 10-5

use is to always initially key the mike 7 times; this assures that charts. Course lines should be drawn in black to be more all controlled lights are turned on to the maximum available distinguishable in low-light conditions. Note prominently intensity. If desired, adjustment can then be made, where the lighted checkpoints along the prepared course. Rotating capability is provided, to a lower intensity by keying 5 and/or beacons at airports, lighted obstructions, lights of cities or 3 times. Due to the close proximity of airports using the same towns, and lights from major highway traffic all provide frequency, radio-controlled lighting receivers may be set at a excellent visual checkpoints. If a global positioning system low sensitivity requiring the aircraft to be relatively close to (GPS) is being used for navigation, ensure that it is working activate the system. Consequently, even when lights are on, properly before the flight. All necessary waypoints should always key the mike as directed when overflying an airport of be loaded properly before the flight and the database should intended landing or just prior to entering the final segment of an be checked for accuracy prior to taking off and then checked approach. This assures the aircraft is close enough to activate again once in flight. The use of radio navigation aids and the system and a full 15-minute lighting duration is available. communication facilities add significantly to the safety and efficiency of night flying. The length limits of the runway are defined by straight lines of lights across the runway ends. At some airports, the runway Check all personal equipment prior to flight to ensure threshold lights are aviation green, and the runway end lights proper functioning and operation. All airplane lights should are aviation red. At many airports, the taxiways are also lighted. be checked for operation by turning them on momentarily A taxiway edge lighting system consists of blue lights that during the preflight inspection. Position lights can be checked outline the usable limits of taxi paths. for loose connections by tapping the light fixture. If the lights blink while being tapped, determine the cause prior Training for Night Flight to flight. Parking ramps should be checked with a flashlight prior to entering the airplane. During the day, it is quite easy Learning to safely fly at night takes time and your proficiency to see stepladders, chuckholes, wheel chocks, and other will improve with experience. Pilot’s should practice the obstructions, but at night, it is more difficult and a check of following maneuvers at night and acquire competency in the area can prevent taxiing mishaps. straight-and-level flight, climbs and descents, level turns, climbing and descending turns, and steep turns. Practicing Starting, Taxiing, and Runup recovery from unusual attitudes should only be done with a flight instructor. Practice these maneuvers with all the Once seated in the airplane and prior to starting the engine, flightdeck lights turned OFF, as well as ON. This blackout arrange all items and materials to be used during the flight so training simulates an electrical or instrument light failure. they will be readily available and convenient to use. Take extra Include using the navigation equipment and local NAVAIDs caution at night to assure the propeller area is clear. Turning during the training. In spite of fewer references or checkpoints, the rotating beacon ON, or flashing the airplane position lights night cross-country flights do not present particular problems if serves to alert persons nearby to remain clear of the propeller. pre-planning is adequate. Continuously monitor position, time To avoid excessive drain of electrical current from the battery, estimates, and fuel consumed. Use NAVAIDs, if available, to it is recommended that unnecessary electrical equipment be assist in monitoring en route progress. turned OFF until after the engine has been started. Preparation and Preflight After starting the engine and when ready to taxi, turn the taxi or landing light ON. Be aware that continuous use of the Night flying requires that pilots are aware of, and operate landing light with revolutions per minute (rpm) power settings within, their abilities and limitations. Although careful normally used for taxiing may place an excessive drain on the planning of any flight is essential, night flying demands more airplane’s electrical system. Also, overheating of the landing attention to the details of preflight preparation and planning. light is possible because of inadequate airflow to carry the heat away. Use landing lights only as necessary while taxiing. When Preparation for a night flight includes a thorough review of using lights, consideration should be given to not blinding the available weather reports and forecasts with particular other pilots. Taxi slowly, particularly in congested areas. If attention given to temperature/dew point spread. A narrow taxi lines are painted on the ramp or taxiway, follow the lines temperature/dew point spread may indicate the possibility to ensure a proper path along the route. of fog. Emphasis should also be placed on wind direction and speed, since its effect on the airplane cannot be as easily Use the checklist for the before takeoff and run-up checks detected at night as during the day. and procedures. During the day, forward movement of the airplane can be detected easily. At night, the airplane could On night cross-country flights, select and use appropriate creep forward without being noticed unless the pilot is alert aeronautical charts to include the appropriate adjacent 10-6

for this possibility. Hold or lock the brakes during the run-up After becoming airborne, the darkness of night often makes and be alert for any forward movement. An instrument check it difficult to note whether the airplane is getting closer to or should be done while taxiing to check for proper and correct farther from the surface. To ensure the airplane continues in operation prior to takeoff. a positive climb, be sure a climb is indicated on the attitude indicator, vertical speed indicator (VSI), and altimeter. It is Takeoff and Climb also important to ensure the airspeed is at best climb speed. Night flying is very different from day flying and demands Make necessary pitch and bank adjustments by referencing more attention of the pilot. The most noticeable difference the attitude and heading indicators. It is recommended is the limited availability of outside visual references. that turns not be made until reaching a safe maneuvering Therefore, flight instruments should be used to a greater altitude. Although the use of the landing lights is helpful degree in controlling the airplane. This is particularly true during the takeoff, they become ineffective after the airplane on night takeoffs and climbs. Adjust the flightdeck lights to has climbed to an altitude where the light beam no longer a minimum brightness that allow reading the instruments and extends to the surface. The light can cause distortion when switches but not hinder outside vision. This also eliminates it is reflected by haze, smoke, or clouds that might exist in light reflections on the windshield and windows. the climb. Therefore, when the landing light is used for the takeoff, turn it off after the climb is well established provided After ensuring that the final approach and runway are clear of it is not being used for collision avoidance. other air traffic, or when cleared for takeoff by the air traffic controller, turn the landing and taxi lights ON and line the Orientation and Navigation airplane up with the centerline of the runway. If the runway does not have centerline lighting, use the painted centerline Generally, at night, it is difficult to see clouds and restrictions and the runway edge lights. After the airplane is aligned, note to visibility, particularly on dark nights or under overcast. the heading indicator and set to correspond to the known When flying under VFR, pilots must exercise caution to runway direction. To begin the takeoff, release the brakes avoid flying into clouds. Usually, the first indication of and advance the throttle smoothly to maximum allowable flying into restricted visibility conditions is the gradual power. As the airplane accelerates, it should be kept moving disappearance of lights on the ground. If the lights begin straight ahead between and parallel to the runway edge lights. to take on an appearance of being surrounded by a halo or glow, use caution in attempting further flight in that same The procedure for night takeoffs is the same as for normal direction. Such a halo or glow around lights on the ground daytime takeoffs except that many of the runway visual cues are is indicative of ground fog. Remember that if a descent must not available. Check the flight instruments frequently during the be made through clouds, smoke, or haze in order to land, takeoff to ensure the proper pitch attitude, heading, and airspeed the horizontal visibility is considerably less when looking are being attained. As the airspeed reaches the normal lift-off through the restriction than it is when looking straight down speed, adjust the pitch attitude to establish a normal climb. through it from above. Under no circumstances should a Accomplish this by referring to both outside visual references, VFR night flight be made during poor or marginal weather such as lights, and to the flight instruments. [Figure 10-3] conditions unless both the pilot and aircraft are certificated and equipped for flight under instrument flight rules (IFR). 24 W 30Crossing large bodies of water at night in single-engine airplanes could be potentially hazardous, in the event of an 24 W 30engine failure, the pilot may not have any option than to land (ditch) the airplane in the water. Another hazard faced by pilots of all aircraft, due to limited or no lighting, is that OBS the horizon blends with the water. During poor visibility conditions over water, the horizon becomes obscure and may result in a loss of orientation. Even on clear nights, the stars may be reflected on the water surface, which could appear as a continuous array of lights, thus making the horizon difficult to identify. OBS Figure 10-3. Establish a positive climb. 10-7

Lighted runways, buildings, or other objects may cause landing checklist. If the heading indicator contains a heading illusions to the pilot when seen from different altitudes. At bug, setting it to the runway heading is an excellent reference an altitude of 2,000 feet, a group of lights on an object may for the pattern legs. be seen individually, while at 5,000 feet or higher, the same lights could appear to be one solid light mass. These illusions Maintain the recommended airspeeds and execute the may become quite acute with altitude changes and, if not approach and landing in the same manner as during the overcome, could present problems in respect to approaches day. A low, shallow approach is definitely inappropriate to lighted runways. during a night operation. The altimeter and VSI should be constantly cross-checked against the airplane’s position along Approaches and Landings the base leg and final approach. A visual approach slope indicator (VASI) is an indispensable aid in establishing and When approaching the airport to enter the traffic pattern and maintaining a proper glide path. [Figure 10-5] land, it is important that the runway lights and other airport lighting be identified as early as possible. If the airport layout After turning onto the final approach and aligning the is unfamiliar, sighting of the runway may be difficult until airplane midway between the two rows of runway-edge very close-in due to the maze of lights observed in the area. lights, note and correct for any wind drift. Throughout the [Figure 10-4] Fly toward the rotating beacon until the lights final approach, use pitch and power to maintain a stabilized outlining the runway are distinguishable. To fly a traffic approach. Flaps are used the same as in a normal approach. pattern of proper size and direction, the runway threshold Usually, halfway through the final approach, the landing and runway-edge lights must be positively identified. Once light is turned on. Earlier use of the landing light may be the airport lights are seen, these lights should be kept in sight necessary because of “Operation Lights ON” or for local throughout the approach. traffic considerations. The landing light is sometimes ineffective since the light beam will usually not reach Distance may be deceptive at night due to limited lighting the ground from higher altitudes. The light may even be conditions. A lack of intervening references on the ground reflected back into the pilot’s eyes by any existing haze, and the inability to compare the size and location of different smoke, or fog. This disadvantage is overshadowed by the ground objects cause this. This also applies to the estimation safety considerations provided by using the “Operation of altitude and speed. Consequently, more dependence must Lights ON” procedure around other traffic. be placed on flight instruments, particularly the altimeter and the airspeed indicator. When entering the traffic pattern, The round out and touchdown is made in the same manner as always give yourself plenty of time to complete the before in day landings. At night, the judgment of height, speed, and sink rate is impaired by the scarcity of observable objects in the landing area. An inexperienced pilot may have a tendency Below glidepath On glidepath Above glidepath Far Bar Far Bar Far Bar Near Bar Near Bar Near Bar If you see red over If the far bar is red If both light bars are red, you are below and the near bar is white, you are too glidepath. white, you are on the high. glidepath. Figure 10-5. VASI. The memory aid “red over white, you’re all right,” is helpful in recalling the correct sequence of light. Figure 10-4. Use light patterns for orientation. 10-8

to round out too high until attaining familiarity with the proper Night Emergencies height for the correct round out. To aid in determining the Perhaps the greatest concern about flying a single-engine proper round out point, continue a constant approach descent airplane at night is the possibility of a complete engine failure until the landing lights reflect on the runway and tire marks on and the subsequent emergency landing. This is a legitimate the runway can be seen clearly. At this point, the round out is concern, even though continuing flight into adverse weather started smoothly and the throttle gradually reduced to idle as and poor pilot judgment account for most serious accidents. the airplane is touching down. [Figure 10-6] During landings without the use of landing lights, the round out may be started If the engine fails at night, there are several important when the runway lights at the far end of the runway first appear procedures and considerations to keep in mind. They are to be rising higher than the nose of the airplane. This demands as follows: a smooth and very timely round out and requires that the pilot feel for the runway surface using power and pitch changes, • Maintain positive control of the airplane and as necessary, for the airplane to settle slowly to the runway. establish the best glide configuration and airspeed. Blackout landings should always be included in night pilot Turn the airplane towards an airport or away from training as an emergency procedure. congested areas. • Check to determine the cause of the engine malfunction, such as the position of fuel selectors, magneto switch, or primer. If possible, the cause of the malfunction should be corrected immediately and the engine restarted. • Announce the emergency situation to air traffic control (ATC) or Universal Communications (UNICOM). If already in radio contact with a facility, do not change frequencies unless instructed to change. • If the condition of the nearby terrain is known and is suitable for a forced landing, turn towards an unlighted portion of the area and plan an emergency forced landing to an unlighted portion. • Consider an emergency landing area close to public access if possible. This may facilitate rescue or help, if needed. • Maintain orientation with the wind to avoid a downwind landing. • Complete the before landing checklist, and check the landing lights for operation at altitude and turn ON in sufficient time to illuminate the terrain or obstacles along the flightpath. The landing should be completed in the normal landing attitude at the slowest possible airspeed. If the landing lights are unusable and outside visual references are not available, the airplane should be held in level-landing attitude until the ground is contacted. • After landing, turn off all switches and evacuate the airplane as quickly as possible. Chapter Summary Night operations present additional risks that must be identified and assessed. Night flying operations should not be encouraged or attempted, except by pilots that are certificated, current, and proficient in night flying. Prior to Figure 10-6. Roundout when tire marks are visible. 10-9

attempting night operations, pilots should receive training and be familiar with the risks associated with night flight and how they differ from daylight operations. Even for experienced pilots, night VFR operations should only be conducted in unrestricted visibility, favorable winds, both on the surface and aloft, and no turbulence. Additional information on pilot vision and illusions can be found in FAA brochure AM-400- 98/2 and also Chapters 2 and 17 of the Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25A) at www.faa. gov. Additional information on lighting aids can be found in Chapter 2 of the Aeronautical Information Manual (AIM), which can be accessed at www.faa.gov. 10-10

TCharptear11nsition to Complex Airplanes Introduction A high-performance airplane is defined as an airplane with an engine capable of developing more than 200 horsepower. A complex airplane is an airplane that has a retractable landing gear, flaps, and a controllable pitch propeller. In lieu of a controllable pitch propeller, the aircraft could also have an engine control system consisting of a digital computer and associated accessories for controlling the engine and the propeller. A seaplane would still be considered complex if it meets the description above except for having floats instead of a retractable landing gear system. 11-1

Straight Elliptical Tapered Delta Sweptback Figure 11-1. Airfoil types. Transition to a complex airplane, or a high-performance axis. Wing flaps acts symmetrically about the longitudinal airplane, can be demanding for most pilots without previous axis producing no rolling moment; however, both lift and drag experience. Increased performance and complexity both increase as well as a pitching moment about the lateral axis. require additional planning, judgment, and piloting skills. Lift is a function of several variables including air density, Transition to these types of airplanes, therefore, should be velocity, surface area, and lift coefficient. Since flaps increase accomplished in a systematic manner through a structured an airfoil’s lift coefficient, lift is increased. [Figure 11-3] course of training administered by a qualified flight instructor. As flaps are deflected, the aircraft may pitch nose up, nose Airplanes can be designed to fly through a wide range of down or have minimal changes in pitch attitude. Pitching airspeeds. High speed flight requires smaller wing areas and moment is caused by the rearward movement of the moderately cambered airfoils whereas low speed flight is wing’s center of pressure; however, that pitching behavior obtained with airfoils with a greater camber and larger wing depends on several variables including flap type, wing area. [Figure 11-1] Many compromises are often made by position, downwash behavior, and horizontal tail location. designers to provide for higher speed cruise flight and low speeds for landing. Flaps are a common design effort to Mean camber line Increased camber increase an airfoil’s camber and the wing’s surface area for lower speed flight. [Figure 11-2] Since an airfoil cannot have two different cambers at the same Aifoil with flap extended time, one of two things must be done. Either the airfoil can be a compromise, or a cruise airfoil can be combined with CL Stalled airfoil a device for increasing the camber of the airfoil for low- CL, max flapped Normal airfoil speed flight. Camber is the asymmetry between the top and CL, max normal the bottom surfaces of an airfoil. One method for varying Angle of attack an airfoil’s camber is the addition of trailing-edge flaps. Simple flapped airfoil Engineers call these devices a high-lift system. Figure 11-2. Coefficient of lift comparison for flap extended and Function of Flaps retracted positions. Flaps work primarily by changing the camber of the airfoil which increases the wing’s lift coefficient and with some flap designs the surface area of the wing is also increased. Flap deflection does not increase the critical (stall) angle of attack (AOA) and, in some cases, flap deflection actually decreases the critical AOA. Deflection of a wing’s control surfaces, such as ailerons and flaps, alters both lift and drag. With aileron deflection, there is asymmetrical lift which imparts a rolling moment about the airplane’s longitudinal 11-2

L = 1 pV 2 SCL Plain flap 2 Split flap L = Lift produced P = Air density V = Velocity relative to the air S = Surface area of the wing CL = lift coefficient which is determined by the camber of the airfoil used, the chord of the wing and AOA Figure 11-3. Lift equation. Consequently, pitch behavior depends on the design features of the particular airplane. Flap deflection of up to 15° primarily produces lift with Slotted flap minimal increases in drag. Deflection beyond 15° produces a Fowler flap large increase in drag. Drag from flap deflection is parasite drag and, as such, is proportional to the square of the speed. Also, deflection beyond 15° produces a significant nose-up pitching moment in most high-wing airplanes because the resulting downwash increases the airflow over the horizontal tail. Flap Effectiveness Flap effectiveness depends on a number of factors, but the most noticeable are size and type. For the purpose of this chapter, trailing edge flaps are classified as four basic types: plain (hinge), split, slotted, and Fowler. [Figure 11-4] The plain or hinge flap is a hinged section of the wing. The Figure 11-4. Four basic types of flaps. structure and function are comparable to the other control surfaces—ailerons, rudder, and elevator. The split flap is deflections are much like the slotted flap. Fowler flaps are more complex. It is the lower or underside portion of the most commonly used on larger airplanes because of their wing; deflection of the flap leaves the upper trailing edge structural complexity and difficulty in sealing the slots. of the wing undisturbed. It is, however, more effective than the hinge flap because of greater lift and less pitching Operational Procedures moment, but there is more drag. Split flaps are more useful It would be impossible to discuss all the many airplane design for landing, but the partially deflected hinge flaps have the and flap combinations. This emphasizes the importance of the advantage in takeoff. The split flap has significant drag at Federal Aviation Administration (FAA) approved Airplane small deflections, whereas the hinge flap does not because Flight Manual and/or Pilot’s Operating Handbook (AFM/ airflow remains “attached” to the flap. POH) for a given airplane. While some AFM/POHs are specific as to operational use of flaps, others leave the use The slotted flap has a gap between the wing and the leading of flaps to pilot discretion. Hence, flap operation makes pilot edge of the flap. The slot allows high-pressure airflow on judgment of critical importance. Since flap operation is used the wing undersurface to energize the lower pressure over for landings and takeoffs, during which the airplane is in close the top, thereby delaying flow separation. The slotted flap proximity to the ground where the margin for error is small. has greater lift than the hinge flap but less than the split flap; but, because of a higher lift-drag ratio, it gives better takeoff Since the recommendations given in the AFM/POH are and climb performance. Small deflections of the slotted flap based on the airplane and the flap design, the pilot must give a higher drag than the hinge flap but less than the split. relate the manufacturer’s recommendation to aerodynamic This allows the slotted flap to be used for takeoff. effects of flaps. This requires basic background knowledge of flap aerodynamics and geometry. With this information, The Fowler flap deflects down and aft to increase the wing a decision as to the degree of flap deflection and time of area. This flap can be multi-slotted making it the most complex deflection based on runway and approach conditions relative of the trailing-edge systems. This system does, however, give to the wind conditions can be made. the maximum lift coefficient. Drag characteristics at small 11-3

The time of flap extension and degree of deflection are related. is used to offset this pitching moment. Application of full Large flap deflections at one single point in the landing power in the go-around increases the airflow over the wing. pattern produce large lift changes that require significant This produces additional lift causing significant changes in pitch and power changes in order to maintain airspeed and pitch. The pitch-up tendency does not diminish completely glide slope. Incremental deflection of flaps on downwind, with flap retraction because of the trim setting. Expedient base, and final approach allow smaller adjustment of pitch retraction of flaps is desirable to eliminate drag; however, and power compared to extension of full flaps all at one time. the pilot must be prepared for rapid changes in pitch forces as This procedure facilitates a more stabilized approach. the result of trim and the increase in airflow over the control surfaces. [Figure 11-5] While all landings should be accomplished at the slowest speed possible for a given situation, a soft or short-field The degree of flap deflection combined with design landing requires minimal speed at touchdown while a short configuration of the horizontal tail relative to the wing require field obstacle approach requires minimum speed and a steep carefully monitoring of pitch and airspeed, carefully control approach angle. Flap extension, particularly beyond 30°, results flap retraction to minimize altitude loss, and properly use in significant levels of drag. As such, large angles of flap the rudder for coordination. Considering these factors, it is deployment require higher power settings than used with partial good practice to extend the same degree of flap deflection at flaps. When steep approach angles and short fields combine the same point in the landing pattern for each landing. This with power to offset the drag produced by the flaps, the landing requires that a consistent traffic pattern be used. This allows flare becomes critical. The drag produces a high sink rate that for a preplanned go-around sequence based on the airplane’s must be controlled with power, yet failure to reduce power at a position in the landing pattern. rate so that the power is idle at touchdown allows the airplane to float down the runway. A reduction in power too early can There is no single formula to determine the degree of flap result in a hard landing and damage or loss of control. deflection to be used on landing because a landing involves variables that are dependent on each other. The AFM/POH Crosswind component is another factor to be considered in for the particular airplane contains the manufacturer’s the degree of flap extension. The deflected flap presents a recommendations for some landing situations. On the other surface area for the wind to act on. With flaps extended in a hand, AFM/POH information on flap usage for takeoff is crosswind, the wing on the upwind side is more affected than more precise. The manufacturer’s requirements are based the downwind wing. The effect is reduced to a slight extent in on the climb performance produced by a given flap design. the crabbed approach since the airplane is more nearly aligned Under no circumstances should a flap setting given in the with the wind. When using a wing-low approach, the lowered AFM/POH be exceeded for takeoff. wing partially blocks the upwind flap. The dihedral of the wing combined with the flap and wind make lateral control Controllable-Pitch Propeller more difficult. Lateral control becomes more difficult as flap extension reaches maximum and the crosswind becomes Fixed-pitch propellers are designed for best efficiency perpendicular to the runway. at one speed of rotation and forward speed. This type of propeller provides suitable performance in a narrow range With flaps extended, the crosswind effects on the wing of airspeeds; however, efficiency would suffer considerably become more pronounced as the airplane comes closer to the outside this range. To provide high-propeller efficiency ground. The wing, flap, and ground form a “container” that through a wide range of operation, the propeller blade angle is filled with air by the crosswind. Since the flap is located must be controllable. The most effective way of controlling behind the main landing gear when the wind strikes the the propeller blade angle is by means of a constant-speed deflected flap and fuselage side, the upwind wing tends to rise governing system. and the airplane tends to turn into the wind. Proper control position is essential for maintaining runway alignment. Constant-Speed Propeller Depending on the amount of crosswind, it may be necessary The constant-speed propeller keeps the blade angle adjusted to retract the flaps soon after touchdown in order to maintain for maximum efficiency for most conditions of flight. The control of the airplane. pilot controls the engine revolutions per minute (rpm) indirectly by means of a propeller control in the flightdeck, The go-around is another factor to consider when making which is connected to a propeller governor. For maximum a decision about degree of flap deflection and about where takeoff power, the propeller control is moved all the way in the landing pattern to extend flaps. Because of the nose forward to the low pitch/high rpm position, and the throttle is down pitching moment produced with flap extension, trim moved forward to the maximum allowable manifold pressure 11-4

Center of pressure with flaps extended Center of pressure – Lift Pitching moment Tail down force Center of gravity Center of pressure – Lift Pitching moment Tail down force Center of gravity Figure 11-5. Flaps extended pitching moment. position. [Figure 11- 6] To reduce power for climb or cruise, the propeller control causes the propeller blades to move to a manifold pressure is reduced to the desired value with the higher angle. Increasing the propeller blade angle (of attack) throttle, and the engine rpm is reduced by moving the propeller results in an increase in the resistance of the air. This puts control back toward the high pitch/low rpm position until the a load on the engine so it slows down. In other words, the desired rpm is observed on the tachometer. Pulling back on resistance of the air at the higher blade angle is greater than High pitch – Low RPM Low pitch – High RPM Figure 11-6. Controllable pitch propeller pitch angles. 11-5

the torque, or power, delivered to the propeller by the engine, blade angle (pitch). The low blade angle keeps the AOA, so it slows down to a point where forces are in balance. with respect to the relative wind, small and efficient at the low speed. [Figure 11-7] When an aircraft engine is running at constant speed, the torque (power) exerted by the engine at the propeller shaft At the same time, it allows the propeller to handle a smaller must equal the opposing load provided by the resistance of the mass of air per revolution. This light load allows the engine air. The rpm is controlled by regulating the torque absorbed to turn at maximum rpm and develop maximum power. by the propeller—in other words by increasing or decreasing Although the mass of air per revolution is small, the number the resistance offered by the air to the propeller. This is of rpm is high. Thrust is maximum at the beginning of the accomplished with a constant-speed propeller by means of a takeoff and then decreases as the airplane gains speed and governor. The governor, in most cases, is geared to the engine the airplane drag increases. Due to the high slipstream crankshaft and thus is sensitive to changes in engine rpm. velocity during takeoff, the effective lift of the wing behind the propeller(s) is increased. When an airplane is nosed up into a climb from level flight, the engine tends to slow down. Since the governor is sensitive As the airspeed increases after lift-off, the load on the engine to small changes in engine rpm, it decreases the blade angle is lightened because of the small blade angle. The governor just enough to keep the engine speed from falling off. If the senses this and increases the blade angle slightly. Again, the airplane is nosed down into a dive, the governor increases higher blade angle, with the higher speeds, keeps the AOA the blade angle enough to prevent the engine from over- with respect to the relative wind small and efficient. speeding. This allows the engine to maintain a constant rpm thereby maintaining the power output. Changes in airspeed For climb after takeoff, the power output of the engine is and power can be obtained by changing rpm at a constant reduced to climb power by decreasing the manifold pressure manifold pressure; by changing the manifold pressure at a and lowering rpm by increasing the blade angle. At the higher constant rpm; or by changing both rpm and manifold pressure. (climb) airspeed and the higher blade angle, the propeller is The constant-speed propeller makes it possible to obtain an handling a greater mass of air per second at a lower slipstream infinite number of power settings. velocity. This reduction in power is offset by the increase in propeller efficiency. The AOA is again kept small by the Takeoff, Climb, and Cruise increase in the blade angle with an increase in airspeed. During takeoff, when the forward motion of the airplane is at low speeds and when maximum power and thrust are At cruising altitude, when the airplane is in level flight, less required, the constant-speed propeller sets up a low propeller power is required to produce a higher airspeed than is used Angle of attack aFirorspwearedd Angle of attack Relative wind Plane of propeller rotation Relative wind Thrust Chord line (blade face) Plane of propeller rotation Chord line (blade face) Forward motion Stationary Figure 11-7. Propeller blade angle. 11-6

in climb. Consequently, engine power is again reduced by limits of the propeller blades travel between high and low lowering the manifold pressure and increasing the blade angle blade angle pitch stops. As long as the propeller blade angle (to decrease rpm). The higher airspeed and higher blade angle is within the governing range and not against either pitch enable the propeller to handle a still greater mass of air per stop, a constant engine rpm is maintained. However, once the second at still smaller slipstream velocity. At normal cruising propeller blade reaches its pitch-stop limit, the engine rpm speeds, propeller efficiency is at or near maximum efficiency. increases or decreases with changes in airspeed and propeller load similar to a fixed-pitch propeller. For example, once a Blade Angle Control specific rpm is selected, if the airspeed decreases enough, the Once the rpm settings for the propeller are selected, the propeller blades reduce pitch in an attempt to maintain the propeller governor automatically adjusts the blade angle to selected rpm until they contact their low pitch stops. From maintain the selected rpm. It does this by using oil pressure. that point, any further reduction in airspeed causes the engine Generally, the oil pressure used for pitch change comes rpm to decrease. Conversely, if the airspeed increases, the directly from the engine lubricating system. When a governor propeller blade angle increases until the high pitch stop is is employed, engine oil is used and the oil pressure is usually reached. The engine rpm then begins to increase. boosted by a pump that is integrated with the governor. The higher pressure provides a quicker blade angle change. The rpm Constant-Speed Propeller Operation at which the propeller is to operate is adjusted in the governor The engine is started with the propeller control in the low head. The pilot changes this setting by changing the position pitch/high rpm position. This position reduces the load or drag of the governor rack through the flightdeck propeller control. of the propeller and the result is easier starting and warm-up of the engine. During warm-up, the propeller blade changing On some constant-speed propellers, changes in pitch are mechanism is operated slowly and smoothly through a full obtained by the use of an inherent centrifugal twisting cycle. This is done by moving the propeller control (with the moment of the blades that tends to flatten the blades toward manifold pressure set to produce about 1,600 rpm) to the high low pitch and oil pressure applied to a hydraulic piston pitch/low rpm position, allowing the rpm to stabilize, and then connected to the propeller blades which moves them toward moving the propeller control back to the low pitch takeoff high pitch. Another type of constant-speed propeller uses position. This is done for two reasons: to determine whether counterweights attached to the blade shanks in the hub. the system is operating correctly and to circulate fresh warm Governor oil pressure and the blade twisting moment move oil through the propeller governor system. Remember the the blades toward the low pitch position, and centrifugal oil has been trapped in the propeller cylinder since the last force acting on the counterweights moves them (and the time the engine was shut down. There is a certain amount blades) toward the high pitch position. In the first case above, of leakage from the propeller cylinder, and the oil tends to governor oil pressure moves the blades towards high pitch congeal, especially if the outside air temperature is low. and in the second case, governor oil pressure and the blade Consequently, if the propeller is not exercised before takeoff, twisting moment move the blades toward low pitch. A loss there is a possibility that the engine may overspeed on takeoff. of governor oil pressure, therefore, affects each differently. An airplane equipped with a constant-speed propeller has Governing Range better takeoff performance than a similarly powered airplane The blade angle range for constant-speed propellers varies equipped with a fixed-pitch propeller. This is because with from about 111⁄2° to 40°. The higher the speed of the airplane, a constant-speed propeller, an airplane can develop its the greater the blade angle range. [Figure 11-8] maximum rated horsepower (red line on the tachometer) while motionless. An airplane with a fixed-pitch propeller, on The range of possible blade angles is termed the propeller’s the other hand, must accelerate down the runway to increase governing range. The governing range is defined by the airspeed and aerodynamically unload the propeller so that Aircraft Type Design Speed (mph) Blade Angle Range Pitch Fixed gear 160 111/2° Low High Retractable 180 15° 101/2° 22° Turbo retractable 225/240 20° 26° Turbine retractable 250/300 30° 11° 34° Transport retractable 325 40° 40° 14° 50/55° 10° 10/15° Figure 11-8. Blade angle range (values are approximate). 11-7

rpm and horsepower can steadily build up to their maximum. • The green arc on the tachometer indicates the normal With a constant-speed propeller, the tachometer reading operating range. When developing power in this range, should come up to within 40 rpm of the red line as soon as the engine drives the propeller. Below the green arc, full power is applied and remain there for the entire takeoff. however, it is usually the windmilling propeller that Excessive manifold pressure raises the cylinder combustion powers the engine. Prolonged operation below the pressures, resulting in high stresses within the engine. green arc can be detrimental to the engine. Excessive pressure also produces high-engine temperatures. A combination of high manifold pressure and low rpm • On takeoffs from low elevation airports, the manifold can induce damaging detonation. In order to avoid these pressure in inches of mercury may exceed the rpm. situations, the following sequence should be followed when This is normal in most cases, but the pilot should making power changes. always consult the AFM/POH for limitations. • When increasing power, increase the rpm first and • All power changes should be made smoothly and then the manifold pressure slowly to avoid over-boosting and/or over-speeding. • When decreasing power, decrease the manifold Turbocharging pressure first and then decrease the rpm The turbocharged engine allows the pilot to maintain The cruise power charts in the AFM/POH should be sufficient cruise power at high altitudes where there is consulted when selecting cruise power settings. Whatever less drag, which means faster true airspeeds and increased the combinations of rpm and manifold pressure listed in range with fuel economy. At the same time, the powerplant these charts—they have been flight tested and approved has flexibility and can be flown at a low altitude without by engineers for the respective airframe and engine the increased fuel consumption of a turbine engine. When manufacturer. Therefore, if there are power settings, such as attached to the standard powerplant, the turbocharger does 2,100 rpm and 24 inches manifold pressure in the power chart, not take any horsepower from the engine to operate; it they are approved for use. With a constant-speed propeller, is relatively simple mechanically, and some models can a power descent can be made without over-speeding the pressurize the cabin as well. engine. The system compensates for the increased airspeed of the descent by increasing the propeller blade angles. If the The turbocharger is an exhaust-driven device that raises the descent is too rapid or is being made from a high altitude, pressure and density of the induction air delivered to the the maximum blade angle limit of the blades is not sufficient engine. It consists of two separate components: a compressor to hold the rpm constant. When this occurs, the rpm is and a turbine connected by a common shaft. The compressor responsive to any change in throttle setting. supplies pressurized air to the engine for high-altitude operation. The compressor and its housing are between the Although the governor responds quickly to any change in ambient air intake and the induction air manifold. The turbine throttle setting, a sudden and large increase in the throttle and its housing are part of the exhaust system and utilize the setting causes a momentary over-speeding of the engine flow of exhaust gases to drive the compressor. [Figure 11-9] until the blades become adjusted to absorb the increased power. If an emergency demanding full power should arise The turbine has the capability of producing manifold pressure during approach, the sudden advancing of the throttle causes in excess of the maximum allowable for the particular engine. momentary over-speeding of the engine beyond the rpm for In order not to exceed the maximum allowable manifold which the governor is adjusted. pressure, a bypass or waste gate is used so that some of the exhaust is diverted overboard before it passes through the Some important points to remember concerning constant- turbine. speed propeller operation are: The position of the waste gate regulates the output of the • The red line on the tachometer not only indicates turbine and therefore, the compressed air available to the maximum allowable rpm; it also indicates the rpm engine. When the waste gate is closed, all of the exhaust required to obtain the engine’s rated horsepower. gases pass through and drive the turbine. As the waste gate opens, some of the exhaust gases are routed around the • A momentary propeller overspeed may occur when turbine through the exhaust bypass and overboard through the throttle is advanced rapidly for takeoff. This is the exhaust pipe. usually not serious if the rated rpm is not exceeded by 10 percent for more than 3 seconds. 11-8

Turbocharger Throttle Body Intake Manifold The turbocharger This regulates airflow Pressurized air from the incorporates a turbine, to the engine. turbocharger is supplied which is driven by exhaust to the cylinders. gases and a compressor that pressurizes the incoming air. Exhaust gas discharge Waste Gas Air Intake Exhaust Manifold This controls the amount Intake air is ducted to the Exhaust gas is ducted of exhaust through the turbocharger where it is through the exhaust turbine. Waste gate compressed. manifold and is used to position is actuated by turn the turbine, which engine oil pressure. drives the compressor. Figure 11-9. Turbocharging system. The waste gate actuator is a spring-loaded piston operated using ground boosting, takeoff manifold pressures may go by engine oil pressure. The actuator, which adjusts the waste as high as 45 \"Hg. gate position, is connected to the waste gate by a mechanical linkage. Although a sea level power setting and maximum rpm can be maintained up to the critical altitude, this does not The control center of the turbocharger system is the pressure mean that the engine is developing sea level power. Engine controller. This device simplifies turbocharging to one power is not determined just by manifold pressure and rpm. control: the throttle. Once the desired manifold pressure is Induction air temperature is also a factor. Turbocharged set, virtually no throttle adjustment is required with changes induction air is heated by compression. This temperature in altitude. The controller senses compressor discharge rise decreases induction air density, which causes a power requirements for various altitudes and controls the oil loss. Maintaining the equivalent horsepower output requires pressure to the waste gate actuator, which adjusts the waste a somewhat higher manifold pressure at a given altitude than gate accordingly. Thus the turbocharger maintains only the if the induction air were not compressed by turbocharging. manifold pressure called for by the throttle setting. If, on the other hand, the system incorporates an automatic density controller which, instead of maintaining a constant Ground Boosting Versus Altitude Turbocharging manifold pressure, automatically positions the waste gate Altitude turbocharging (sometimes called “normalizing”) so as to maintain constant air density to the engine, a near is accomplished by using a turbocharger that maintains constant horsepower output results. maximum allowable sea level manifold pressure (normally 29–30 \"Hg) up to a certain altitude. This altitude is specified Operating Characteristics by the airplane manufacturer and is referred to as the First and foremost, all movements of the power controls on airplane’s critical altitude. Above the critical altitude, the turbocharged engines should be slow and smooth. Aggressive manifold pressure decreases as additional altitude is gained. and/or abrupt throttle movements increase the possibility of Ground boosting, on the other hand, is an application of over-boosting. Carefully monitor engine indications when turbocharging where more than the standard 29 inches of making power changes. manifold pressure is used in flight. In various airplanes 11-9

When the waste gate is open, the turbocharged engine reacts detonation, which in turn can cause catastrophic engine failure. the same as a normally aspirated engine when the rpm is Turbocharged engines are especially heat sensitive. The key varied. That is, when the rpm is increased, the manifold to turbocharger operation is effective heat management. pressure decreases slightly. When the engine rpm is decreased, the manifold pressure increases slightly. However, Monitor the condition of a turbocharged engine with manifold when the waste gate is closed, manifold pressure variation pressure gauge, tachometer, exhaust gas temperature/turbine with engine rpm is just the opposite of the normally aspirated inlet temperature gauge, and cylinder head temperature. engine. An increase in engine rpm results in an increase in Manage the “heat system” with the throttle, propeller rpm, manifold pressure, and a decrease in engine rpm results in a mixture, and cowl flaps. At any given cruise power, the mixture decrease in manifold pressure. is the most influential control over the exhaust gas/TIT. The throttle regulates total fuel flow, but the mixture governs the Above the critical altitude, where the waste gate is closed, fuel to air ratio. The mixture, therefore, controls temperature. any change in airspeed results in a corresponding change in manifold pressure. This is true because the increase in ram Exceeding temperature limits in an after takeoff climb is air pressure with an increase in airspeed is magnified by the usually not a problem since a full rich mixture cools with compressor resulting in an increase in manifold pressure. excess fuel. At cruise, power is normally reduced and The increase in manifold pressure creates a higher mass flow mixture adjusted accordingly. Under cruise conditions, through the engine, causing higher turbine speeds and thus monitor temperature limits closely because that is when the further increasing manifold pressure. temperatures are most likely to reach the maximum, even though the engine is producing less power. Overheating in When running at high altitudes, aviation gasoline may tend an en route climb, however, may require fully open cowl to vaporize prior to reaching the cylinder. If this occurs in the flaps and a higher airspeed. portion of the fuel system between the fuel tank and the engine- driven fuel pump, an auxiliary positive pressure pump may Since turbocharged engines operate hotter at altitude than do be needed in the tank. Since engine-driven pumps pull fuel, normally aspirated engines, they are more prone to damage they are easily vapor locked. A boost pump provides positive from cooling stress. Gradual reductions in power and careful pressure—pushes the fuel—reducing the tendency to vaporize. monitoring of temperatures are essential in the descent phase. Extending the landing gear during the descent may Heat Management help control the airspeed while maintaining a higher engine Turbocharged engines must be thoughtfully and carefully power setting. This allows the pilot to reduce power in small operated with continuous monitoring of pressures and increments which allows the engine to cool slowly. It may temperatures. There are two temperatures that are especially also be necessary to lean the mixture slightly to eliminate important—turbine inlet temperature (TIT) or, in some roughness at the lower power settings. installations, exhaust gas temperature (EGT) and cylinder head temperature. TIT or EGT limits are set to protect the Turbocharger Failure elements in the hot section of the turbocharger, while cylinder Because of the high temperatures and pressures produced head temperature limits protect the engine’s internal parts. in the turbine exhaust systems, any malfunction of the turbocharger must be treated with extreme caution. In Due to the heat of compression of the induction air, a all cases of turbocharger operation, the manufacturer’s turbocharged engine runs at higher operating temperatures recommended procedures should be followed. This is than a non-turbocharged engine. Because turbocharged especially so in the case of turbocharger malfunction. engines operate at high altitudes; their environment is less However, in those instances where the manufacturer’s efficient for cooling. At altitude, the air is less dense and, procedures do not adequately describe the actions to be therefore, cools less efficiently. Also, the less dense air causes taken in the event of a turbocharger failure, the following the compressor to work harder. Compressor turbine speeds procedures should be used. can reach 80,000–100,000 rpm, adding to the overall engine operating temperatures. Turbocharged engines are also Over-Boost Condition operated at higher power settings a greater portion of the time. If an excessive rise in manifold pressure occurs during normal advancement of the throttle (possibly owing to faulty High heat is detrimental to piston engine operation. Its operation of the waste gate): cumulative effects can lead to piston, ring, and cylinder head failure and place thermal stress on other operating • Immediately retard the throttle smoothly to limit the components. Excessive cylinder head temperature can lead to manifold pressure below the maximum for the rpm and mixture setting 11-10