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occur during the approach and landing phases of a flight. Aviation Administration (FAA)-approved Airplane Flight recommendations take precedence.
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8-1IntroductionThere is a saying that while takeoff is optional, landing is mandatory. Unfortunately, a review of accident statistics indicates that over 45 percent of all general aviation accidents occur during the approach and landing phases of a flight. A closer look shows that the cause of over 90 percent of those cases was pilot related and loss of control was also a major contributing factor in 33 percent of the cases. While the requirement to maneuver close to the ground cannot be eliminated, pilots can develop the skills and follow established procedures to reduce the likelihood of an accident or mishap. This chapter focuses on the approach to landing, factors that affect landings, types of landings, and aspects of faulty landings.Approaches and Landings Chapter 8
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8-2Figure 8-1. Base leg and final approach.3618Normal Approach and LandingA normal approach and landing involves the use of procedures for what is considered a normal situation; that is, when engine power is available, the wind is light, or the final approach is made directly into the wind, the final approach path has no obstacles and the landing surface is firm and of ample length to gradually bring the airplane to a stop. The selected landing point is normally beyond the runway™s approach threshold but within the first 13 portion of the runway.The factors involved and the procedures described for the normal approach and landing also have applications to the other-than-normal approaches and landings and are discussed later in this chapter. This being the case, the principles of normal operations are explained first and must be understood before proceeding to the more complex operations. To help the pilot better understand the factors that influence judgment and procedures, the last part of the approach pattern and the actual landing is divided into five phases: 1. the base leg 2. the final approach 3. the round out (flare) 4. the touchdown 5. the after-landing rollIt must be remembered that the manufacturer™s recommended procedures, including airplane configuration and airspeeds, and other information relevant to approaches and landings in a specific make and model airplane are contained in the Federal Aviation Administration (FAA)-approved Airplane Flight Manual and/or Pilot™s Operating Handbook (AFM/POH) for that airplane. If any of the information in this chapter differs from the airplane manufacturer™s recommendations as contained in the AFM/POH, the airplane manufacturer™s recommendations take precedence.Base LegThe placement of the base leg is one of the more important judgments made by the pilot in any landing approach. [Figure 8-1] The pilot must accurately judge the altitude and distance from which a gradual, stabilized descent results in landing at the desired spot. The distance depends on the altitude of the base leg, the effect of wind, and the amount of wing flaps used. When there is a strong wind on final approach or the flaps are used to produce a steep angle of descent, the base leg must be positioned closer to the approach end of the runway than would be required with a light wind or no flaps. Normally, the landing gear is extended and the before-landing check completed prior to reaching the base leg.After turning onto the base leg, start the descent with reduced power and airspeed of approximately 1.4 V SO, which is the
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8-3Figure 8-2. Effect of headwind on final approach.Strong headwind34Normal best glide speed flightpathIncreased airspeed flightpath stalling speed with power off, landing gear and flaps down. For example, if VSO is 60 knots, the speed should be 1.4 times 60 or 84 knots. Landing flaps may be partially lowered, if desired, at this time. Full flaps are not recommended until the final approach is established. A drift correction is established and maintained to follow a ground track perpendicular to the extension of the centerline of the runway on which the landing is to be made. Since the final approach and landing are normally made into the wind, there is somewhat of a crosswind during the base leg. This requires that the airplane be angled sufficiently into the wind to prevent drifting farther away from the intended landing spot.The base leg is continued to the point where a medium to shallow-banked turn aligns the airplane™s path directly with the centerline of the landing runway. This descending turn is completed at a safe altitude and dependent upon the height of the terrain and any obstructions along the ground track. The turn to the final approach is sufficiently above the airport elevation to permit a final approach long enough to accurately estimate the resultant point of touchdown while maintaining the proper approach airspeed. This requires careful planning as to the starting point and the radius of the turn. Normally, it is recommended that the angle of bank not exceed a medium bank because the steeper the angle of bank, the higher the airspeed at which the airplane stalls. Since the base-to-final turn is made at a relatively low altitude, it is important that a stall not occur at this point. If an extremely steep bank is needed to prevent overshooting the proper final approach path, it is advisable to discontinue the approach, go around, and plan to start the turn earlier on the next approach rather than risk a hazardous situation.Final ApproachAfter the base-to-final approach turn is completed, the longitudinal axis of the airplane is aligned with the centerline of the runway or landing surface so that drift (if any) is recognized immediately. On a normal approach, with no wind drift, the longitudinal axis is kept aligned with the runway centerline throughout the approach and landing. (The proper way to correct for a crosswind is explained under the section, Crosswind Approach and Landing. For now, only an approach and landing where the wind is straight down the runway are discussed.)After aligning the airplane with the runway centerline, the final flap setting is completed and the pitch attitude adjusted as required for the desired rate of descent. Slight adjustments in pitch and power may be necessary to maintain the descent attitude and the desired approach airspeed. In the absence of the manufacturer™s recommended airspeed, a speed equal to 1.3 VSO should be used. If VSO is 60 knots, the speed should be 78 knots. When the pitch attitude and airspeed have been stabilized, the airplane is re-trimmed to relieve the pressures being held on the controls.A stabilized descent angle is controlled throughout the approach so that the airplane lands in the center of the first third of the runway. The descent angle is affected by all four fundamental forces that act on an airplane (lift, drag, thrust, and weight). If all the forces are constant, the descent angle is constant in a no-wind condition. The pilot controls these forces by adjusting the airspeed, attitude, power, and drag (flaps or forward slip). The wind also plays a prominent part in the gliding distance over the ground [Figure 8-2]; the pilot does not have control over the wind but corrects for its effect on the airplane™s descent by appropriate pitch and power adjustments.Considering the factors that affect the descent angle on the final approach, for all practical purposes at a given pitch attitude there is only one power setting for one airspeed, one
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8-4Figure 8-3. Effect of flaps on the landing point.34No flapsHalf flapsFull flaps with: constant airspeed constant power flap setting, and one wind condition. A change in any one of these variables requires an appropriate coordinated change in the other controllable variables. For example, if the pitch attitude is raised too high without an increase of power, the airplane settles very rapidly and touches down short of the desired spot. For this reason, never try to stretch a glide by applying back-elevator pressure alone to reach the desired landing spot. This shortens the gliding distance if power is not added simultaneously. The proper angle of descent and airspeed is maintained by coordinating pitch attitude changes and power changes.The objective of a good, stabilized final approach is to descend at an angle and airspeed that permits the airplane to reach the desired touchdown point at an airspeed that results in minimum floating just before touchdown; in essence, a semi-stalled condition. To accomplish this, it is essential that both the descent angle and the airspeed be accurately controlled. Since on a normal approach the power setting is not fixed as in a power-off approach, the power and pitch attitude are adjusted simultaneously as necessary to control the airspeed and the descent angle, or to attain the desired altitudes along the approach path. By lowering the nose and reducing power to keep approach airspeed constant, a descent at a higher rate can be made to correct for being too high in the approach. This is one reason for performing approaches with partial power; if the approach is too high, merely lower the nose and reduce the power. When the approach is too low, add power and raise the nose.Use of FlapsThe lift/drag factors are varied by the pilot to adjust the descent through the use of landing flaps. [Figures 8-3 and 8-4] Flap extension during landings provides several advantages by: Ł Producing greater lift and permitting lower landing speed, Ł Producing greater drag, permitting a steeper descent angle without airspeed increase, and Ł Reducing the length of the landing roll. Flap extension has a definite effect on the airplane™s pitch behavior. The increased camber from flap deflection produces lift primarily on the rear portion of the wing. This produces a nose-down pitching moment; however, the change in tail loads from the downwash deflected by the flaps over the horizontal tail has a significant influence on the pitching moment. Consequently, pitch behavior depends on the design features of the particular airplane.Flap deflection of up to 15° primarily produces lift with minimal drag. The airplane has a tendency to balloon up with initial flap deflection because of the lift increase. The nose- down pitching moment, however, tends to offset the balloon. Flap deflection beyond 15° produces a large increase in drag. Also, deflection beyond 15° produces a significant nose-up pitching moment in high-wing airplanes because the resulting downwash increases the airflow over the horizontal tail.The time of flap extension and the degree of deflection are related. Large flap deflections at one single point in the landing pattern produce large lift changes that require significant pitch and power changes in order to maintain airspeed and descent angle. Consequently, there is an advantage to extending flaps in increments while in the landing pattern. Incremental deflection of flaps on downwind, base leg, and final approach allow smaller adjustments of pitch and power compared to extension of full flaps all at one time.When the flaps are lowered, the airspeed decreases unless the power is increased or the pitch attitude lowered. On final approach, the pilot must estimate where the airplane lands
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8-5Figure 8-4. Effect of flaps on the approach angle.34with: constant airspeed constant power No flaps; flatter descent angleHalf flapsFull flaps; steeper descent anglethrough judgment of the descent angle. If it appears that the airplane is going to overshoot the desired landing spot, more flaps are used, if not fully extended, or the power reduced further and the pitch attitude lowered. This results in a steeper approach. If the desired landing spot is being undershot and a shallower approach is needed, both power and pitch attitude are increased to readjust the descent angle. Never retract the flaps to correct for undershooting since that suddenly decreases the lift and causes the airplane to sink rapidly.The airplane must be re-trimmed on the final approach to compensate for the change in aerodynamic forces. With the reduced power and with a slower airspeed, the airflow produces less lift on the wings and less downward force on the horizontal stabilizer resulting in a significant nose-down tendency. The elevator must then be trimmed more nose-up. The round out, touchdown, and landing roll are much easier to accomplish when they are preceded by a proper final approach consisting of precise control of airspeed, attitude, power, and drag resulting in a stabilized descent angle.Estimating Height and MovementDuring the approach, round out, and touchdown; vision is of prime importance. To provide a wide scope of vision and to foster good judgment of height and movement, the pilot™s head should assume a natural, straight-ahead position. Visual focus is not fixed on any one side or any one spot ahead of the airplane. Instead, it is changed slowly from a point just over the airplane™s nose to the desired touchdown zone and back again. This is done while maintaining a deliberate awareness of distance from either side of the runway using your peripheral field of vision.Accurate estimation of distance is, besides being a matter of practice, dependent upon how clearly objects are seen. It requires that the vision be focused properly in order that the important objects stand out as clearly as possible.Speed blurs objects at close range. For example, most everyone has noted this in an automobile moving at high speed. Nearby objects seem to merge together in a blur, while objects farther away stand out clearly. The driver subconsciously focuses the eyes sufficiently far ahead of the automobile to see objects distinctly.The distance at which the pilot™s vision is focused should be proportionate to the speed at which the airplane is traveling over the ground. Thus, as speed is reduced during the round out, the distance ahead of the airplane at which it is possible to focus is brought closer accordingly.If the pilot attempts to focus on a reference that is too close or looks directly down, the reference becomes blurred, [Figure 8-5] and the reaction is either too abrupt or too late. In this case, the pilot™s tendency is to over-control, round out high, and make full-stall, drop-in landings. If the pilot focuses too far ahead, accuracy in judging the closeness of the ground is lost and the consequent reaction is too slow since there does not appear to be a necessity for action. This results in the airplane flying into the ground nose first. The change of visual focus from a long distance to a short distance requires a definite time interval and, even though the time is brief, the airplane™s speed during this interval is such that the airplane travels an appreciable distance, both forward and downward toward the ground.If the focus is changed gradually, being brought progressively closer as speed is reduced, the time interval and the pilot™s reaction are reduced and the whole landing process smoothed out.
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8-6Figure 8-6. Changing angle of attack during roundout.3478 knotsIncrease angle of attack70 knotsIncrease angle of attack65 knotsIncrease angle of attack60 knotsFigure 8-5. Focusing too close blurs vision.Round Out (Flare)The round out is a slow, smooth transition from a normal approach attitude to a landing attitude, gradually rounding out the flightpath to one that is parallel with, and within a very few inches above, the runway. When the airplane, in a normal descent, approaches within what appears to be 10 to 20 feet above the ground, the round out or flare is started. This is a continuous process until the airplane touches down on the ground.As the airplane reaches a height above the ground where a change into the proper landing attitude can be made, back-elevator pressure is gradually applied to slowly increase the pitch attitude and angle of attack (AOA). [Figure 8-6] This causes the airplane™s nose to gradually rise toward the desired landing attitude. The AOA is increased at a rate that allows the airplane to continue settling slowly as forward speed decreases.When the AOA is increased, the lift is momentarily increased and this decreases the rate of descent. Since power normally is reduced to idle during the round out, the airspeed also gradually decreases. This causes lift to decrease again and necessitates raising the nose and further increasing the AOA. During the round out, the airspeed is decreased to touchdown speed while the lift is controlled so the airplane settles gently onto the landing surface. The round out is executed at a rate that the proper landing attitude and the proper touchdown airspeed are attained simultaneously just as the wheels contact the landing surface.The rate at which the round out is executed depends on the airplane™s height above the ground, the rate of descent, and the pitch attitude. A round out started excessively high must be executed more slowly than one from a lower height to allow the airplane to descend to the ground while the proper landing attitude is being established. The rate of rounding out must also be proportionate to the rate of closure with the ground. When the airplane appears to be descending very slowly, the increase in pitch attitude must be made at a correspondingly slow rate.Visual cues are important in flaring at the proper altitude and maintaining the wheels a few inches above the runway until eventual touchdown. Flare cues are primarily dependent on the angle at which the pilot™s central vision intersects the ground (or runway) ahead and slightly to the side. Proper depth perception is a factor in a successful flare, but the visual cues used most are those related to changes in runway or terrain perspective and to changes in the size of familiar objects near the landing area, such as fences, bushes, trees, hangars, and even sod or runway texture. Focus direct central vision at a shallow downward angle from 10° to 15° toward the runway as the round out/flare is initiated. [Figure 8-7] Maintaining the same viewing angle causes the point of visual interception with
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8-8Figure 8-8. A well-executed roundout results in attaining the proper landing attitude.Near zero rate of descent15 feet 2 to 3 feet 1 footto prevent floating or skipping and allows the full weight of the airplane to rest on the wheels for better braking action.It is extremely important that the touchdown occur with the airplane™s longitudinal axis exactly parallel to the direction in which the airplane is moving along the runway. Failure to accomplish this imposes severe side loads on the landing gear. To avoid these side stresses, do not allow the airplane to touch down while turned into the wind or drifting.After-Landing RollThe landing process must never be considered complete until the airplane decelerates to the normal taxi speed during the landing roll or has been brought to a complete stop when clear of the landing area. Numerous accidents occur as a result of pilots abandoning their vigilance and failing to maintain positive control after getting the airplane on the ground.A pilot must be alert for directional control difficulties immediately upon and after touchdown due to the ground friction on the wheels. Loss of directional control may lead to an aggravated, uncontrolled, tight turn on the ground, or a ground loop. The combination of centrifugal force acting on the center of gravity (CG) and ground friction of the main wheels resisting it during the ground loop may cause the airplane to tip or lean enough for the outside wingtip to contact the ground. This imposes a sideward force that could collapse the landing gear.The rudder serves the same purpose on the ground as it does in the airŠit controls the yawing of the airplane. The effectiveness of the rudder is dependent on the airflow, which depends on the speed of the airplane. As the speed decreases and the nose wheel has been lowered to the ground, the steerable nose provides more positive directional control.The brakes of an airplane serve the same primary purpose as the brakes of an automobileŠto reduce speed on the ground. In airplanes, they are also used as an aid in directional control when more positive control is required than could be obtained with rudder or nose wheel steering alone.To use brakes, on an airplane equipped with toe brakes, the pilot slides the toes or feet up from the rudder pedals to the brake pedals. If rudder pressure is being held at the time braking action is needed, that pressure is not to be released as the feet or toes are being slid up to the brake pedals because control may be lost before brakes can be applied.Putting maximum weight on the wheels after touchdown is an important factor in obtaining optimum braking performance. During the early part of rollout, some lift continues to be generated by the wing. After touchdown, the nose wheel is lowered to the runway to maintain directional control. During deceleration, the nose may pitch down by braking and the weight transferred to the nose wheel from the main wheels. This does not aid in braking action, so back pressure is applied to the controls without lifting the nose wheel off the runway. This enables directional control while keeping weight on the main wheels.Careful application of the brakes is initiated after the nose wheel is on the ground and directional control is established. Maximum brake effectiveness is just short of the point where skidding occurs. If the brakes are applied so hard that skidding takes place, braking becomes ineffective. Skidding is stopped by releasing the brake pressure. Braking effectiveness is not enhanced by alternately applying, releasing, and reapplying brake pressure. The brakes are applied firmly and smoothly as necessary.During the ground roll, the airplane™s direction of movement can be changed by carefully applying pressure on one brake or uneven pressures on each brake in the desired direction. Caution must be exercised when applying brakes to avoid overcontrolling.
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8-9Figure 8-9. Stabilized approach.34Distance traveled in flareTouchdownAiming point (descent angle intersects ground)The ailerons serve the same purpose on the ground as they do in the airŠthey change the lift and drag components of the wings. During the after-landing roll, they are used to keep the wings level in much the same way they are used in flight. If a wing starts to rise, aileron control is applied toward that wing to lower it. The amount required depends on speed because as the forward speed of the airplane decreases, the ailerons become less effective. Procedures for using ailerons in crosswind conditions are explained further in this chapter, in the Crosswind Approach and Landing section.After the airplane is on the ground, back-elevator pressure is gradually relaxed to place weight on the nose wheel to aid in better steering. If available runway permits, the speed of the airplane is allowed to dissipate in a normal manner. Once the airplane has slowed sufficiently and has turned on to the taxiway and stopped, retract the flaps and perform the after- landing checklist. Many accidents have occurred as a result of the pilot unintentionally operating the landing gear control and retracting the gear instead of the flap control when the airplane was still rolling. The habit of positively identifying both of these controls, before actuating them, must be formed from the very beginning of flight training and continued in all future flying activities.Stabilized Approach ConceptA stabilized approach is one in which the pilot establishes and maintains a constant angle glide path towards a predetermined point on the landing runway. It is based on the pilot™s judgment of certain visual clues and depends on the maintenance of a constant final descent airspeed and configuration.An airplane descending on final approach at a constant rate and airspeed is traveling in a straight line toward a spot on the ground ahead. This spot is not the spot on which the airplane touches down because some float occurs during the round out (flare). [Figure 8-9] Neither is it the spot toward which the airplane™s nose is pointed because the airplane is flying at a fairly high AOA, and the component of lift exerted parallel to the Earth™s surface by the wings tends to carry the airplane forward horizontally.The point toward which the airplane is progressing is termed the fiaiming point.fl [Figure 8-9] It is the point on the ground at which, if the airplane maintains a constant glide path and was not flared for landing, it would strike the ground. To a pilot moving straight ahead toward an object, it appears to be stationary. It does not appear to move under the nose of the aircraft and does not appear to move forward away from the aircraft. This is how the aiming point can be distinguishedŠit does not move. However, objects in front of and beyond the aiming point do appear to move as the distance is closed, and they appear to move in opposite directions. During instruction in landings, one of the most important skills a pilot must acquire is how to use visual cues to accurately determine the true aiming point from any distance out on final approach. From this, the pilot is not only able to determine if the glide path results in either an under or overshoot but, taking into account float during round out, the pilot is able to predict the touchdown point to within a few feet.For a constant angle glide path, the distance between the horizon and the aiming point remains constant. If a final approach descent is established and the distance between the perceived aiming point and the horizon appears to increase (aiming point moving down away from the horizon), then the true aiming point, and subsequent touchdown point, is farther down the runway. If the distance between the perceived aiming point and the horizon decreases, meaning that the aiming point is moving up toward the horizon, the true aiming point is closer than perceived.
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8-10Figure 8-10. Runway shape during stabilized approach.Figure 8-11. Change in runway shape if approach becomes narrow or steep.3° approach angle 400 feet x 100 feet runway 1,600 feet from threshold 105 feet altitudeSame runway, same approach angle 800 feet from threshold 52 feet altitudeSame runway, same approach angle 400 feet from threshold 26 feet altitudeToo high Proper descent angleToo low When the airplane is established on final approach, the shape of the runway image also presents clues as to what must be done to maintain a stabilized approach to a safe landing.Obviously, runway is normally shaped in the form of an elongated rectangle. When viewed from the air during the approach, the phenomenon known as perspective causes the runway to assume the shape of a trapezoid with the far end looking narrower than the approach end and the edge lines converging ahead.As an airplane continues down the glide path at a constant angle (stabilized), the image the pilot sees is still trapezoidal but of proportionately larger dimensions. In other words, during a stabilized approach, the runway shape does not change. [Figure 8-10]If the approach becomes shallow, the runway appears to shorten and become wider. Conversely, if the approach is steepened, the runway appears to become longer and narrower. [Figure 8-11]The objective of a stabilized approach is to select an appropriate touchdown point on the runway, and adjust the glide path so that the true aiming point and the desired touchdown point basically coincide. Immediately after rolling out on final approach, adjust the pitch attitude and power so that the airplane is descending directly toward the aiming point at the appropriate airspeed, in the landing configuration, and trimmed for fihands offfl flight. With the approach set up in this manner, the pilot is free to devote full attention toward outside references. Do not stare at any one place, but rather scan from one point to another, such as from the aiming point to the horizon, to the trees and bushes along the runway, to an area well short of the runway, and back to the aiming point. This makes it easier to perceive a deviation from the desired glide path and determine if the airplane is proceeding directly toward the aiming point.If there is any indication that the aiming point on the runway is not where desired, an adjustment must be made to the glide path. This in turn moves the aiming point. For instance, if the aiming point is short of the desired touchdown point and results in an undershoot, an increase in pitch attitude and engine power is warranted. A constant airspeed must be maintained. The pitch and power change, therefore, must be made smoothly and simultaneously. This results in a shallowing of the glide path with the aiming point moving towards the desired touchdown point. Conversely, if the aiming point is farther down the runway than the desired touchdown point resulting in an overshoot, the glide path is steepened by a simultaneous decrease in pitch attitude and
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8-11Figure 8-12. Sideslip.Direction of movementRelative windSideslippower. Once again, the airspeed must be held constant. It is essential that deviations from the desired glide path be detected early so that only slight and infrequent adjustments to glide path are required.The closer the airplane gets to the runway, the larger and more frequent the required corrections become, resulting in an unstable approach. Common errors in the performance of normal approaches and landings are:Ł Inadequate wind drift correction on the base leg.Ł Overshooting or undershooting the turn onto final approach resulting in too steep or too shallow a turn onto final approach.Ł Flat or skidding turns from base leg to final approach as a result of overshooting/inadequate wind drift correction.Ł Poor coordination during turn from base to final approach.Ł Failure to complete the landing checklist in a timely manner.Ł Unstable approach.Ł Failure to adequately compensate for flap extension.Ł Poor trim technique on final approach.Ł Attempting to maintain altitude or reach the runway using elevator alone.Ł Focusing too close to the airplane resulting in a too high round out.Ł Focusing too far from the airplane resulting in a too low round out.Ł Touching down prior to attaining proper landing attitude.Ł Failure to hold sufficient back-elevator pressure after touchdown.Ł Excessive braking after touchdown.Ł Loss of aircraft control during touchdown and roll out. Intentional SlipsA slip occurs when the bank angle of an airplane is too steep for the existing rate of turn. Unintentional slips are most often the result of uncoordinated rudder/aileron application. Intentional slips, however, are used to dissipate altitude without increasing airspeed and/or to adjust airplane ground track during a crosswind. Intentional slips are especially useful in forced landings and in situations where obstacles must be cleared during approaches to confined areas. A slip can also be used as an emergency means of rapidly reducing airspeed in situations where wing flaps are inoperative or not installed.A slip is a combination of forward movement and sideward (with respect to the longitudinal axis of the airplane) movement, the lateral axis being inclined and the sideward movement being toward the low end of this axis (low wing). An airplane in a slip is in fact flying sideways, which results in a change in the direction that the relative wind strikes the airplane. Slips are characterized by a marked increase in drag and corresponding decrease in airplane climb, cruise, and glide performance. It is the increase in drag, however, that makes it possible for an airplane in a slip to descend rapidly without an increase in airspeed.Most airplanes exhibit the characteristic of positive static directional stability and, therefore, have a natural tendency to compensate for slipping. An intentional slip, therefore, requires deliberate cross-controlling ailerons and rudder throughout the maneuver.A fisideslipfl is entered by lowering a wing and applying just enough opposite rudder to prevent a turn. In a sideslip, the airplane™s longitudinal axis remains parallel to the original flightpath, but the airplane no longer flies straight ahead. Instead, the horizontal component of wing lift forces the airplane also to move somewhat sideways toward the low wing. [Figure 8-12] The amount of slip, and therefore the
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