Chapter 8: Approaches and Landings
The risk of an accident is greatest during the approach and landing, compared to any other phase of a flight. Forty-five percent (45%) of all general aviation accidents occur during the approach and landing. An overwhelming percentage of accidents are caused from pilot's lack of proficiency. Correct procedures, when learned and practiced, are a key to attaining proficiency.
Normal Approach and Landing
A normal approach and landing occurs under normal conditions:
The last part of the approach pattern and the actual landing is divided into five phases:
On the base leg, the pilot must accurately judge the altitude and distance from which a gradual, stabilized descent results in landing at the desired spot.
When there is a strong wind on final approach, with flaps deployed, 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.
After turning onto the base leg, start the descent with reduced power and airspeed of approximately 1.4 Vso (140% of stalling speed in a landing configuration).
Full flaps are not recommended until the final approach is established.
In order to follow a ground track perpendicular to the runway's extended centerline (when wind is present), a wind-correction angle is established and maintained. Since landing is normally done into the wind, on base leg the airplane will be angled into the wind sufficiently to cancel the effect of drift.
The base leg is flown to the point where a medium to shallow-banked descending turn aligns the airplane's path with the centerline of the runway. The steeper the angle of bank, the higher the airspeed at which the airplane stalls. Therefore, the turn to final should not be a steep turn. If the pilot overshoots the runway and cannot reacquire the extended centerline with a medium-banked turn, a go-around should be initiated.
On final approach, longitudinal axis of the airplane is aligned with the runway centerline so that drift (if any) is recognized immediately. If no wind is present, the longitudinal axis is kept aligned with the runway centerline throughout the approach and landing.
After aligning the airplane with the runway centerline, the final flap setting is completed and the pitch attitude adjusted for the desired airspeed. Typically, an airspeed of 1.3 Vso (130% of stalling speed) is used. The AFM/POH will provide a specific airspeed for final approach. Power is adjusted to maintain the desired angle of descent.
Adjustments in pitch and power may be necessary to maintain the descent attitude and the desired approach airspeed, with trim applied to relieve control pressures.
A stabilized descent angle is controlled throughout the approach so that the airplane lands in the center of the first third of the runway. When all forces are constant in a no-wind condition, the descent angle is constant. However, when wind is present, the pilot will use pitch and power adjustments to maintain the flightpath to the runway.
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. To achieve this, the descent angle and the airspeed be accurately controlled.
If the approach is too high, lower the nose and reduce the power. If the approach is too low, add power and raise the nose.
Use of Flaps
Flap extension during landings provides several advantages:
Flap extension has a definite effect on the airplane's pitch behavior, which is called a pitching moment. This can be a pitch-up or pitch-down effect when flaps are deployed. The specific 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 will tend to balloon up with initial flap deflection because of the lift increase, while any nose-down pitching moment will tend to offset this.
Flap deflection beyond 15° produces a large increase in drag. It also produces a significant nose-up pitching moment in high-wing airplanes. This is due to the resulting downwash, which increases the airflow over the horizontal tail.
Large flap deflections at one single point in the landing pattern produce large lift changes. This will require the pilot to input significant pitch and power changes in order to maintain airspeed and descent angle. Thus, there is an advantage to extending flaps in increments while in the landing pattern — on the downwind, base, and final approach legs.
When the flaps are lowered, the airspeed decreases. This can be offset by an increase in power and/or a lowering of the pitch attitude.
On final approach, the pilot must estimate the airplane's touchdown point by evaluating the descent angle. If it appears that the airplane is going to overshoot the touchdown point, additional flaps are extended (if available), and/or the power is further reduced, and/or the pitch attitude is lowered.
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.
Flaps are never retracted to correct an undershoot, since this will decrease lift and cause the airplane to sink rapidly.
Estimating Height and Movement
During the approach, round-out, and touchdown, the pilot's head should assume a natural, straight-ahead position to provide a wide scope of vision and to foster good judgment.
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. Peripheral vision is used to maintain a deliberate awareness of distance from either side of the runway.
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. As speed is reduced during the round-out, the focal distance ahead of the airplane becomes closer.
If the pilot attempts to focus on a reference that is too close or looks directly down. The pilot's 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. The consequent reaction is too slow, since there does not appear to be a need for action. This results in the airplane flying into the ground nose first.
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.
The round-out — also called the flare — is a slow, smooth transition from a normal approach attitude to a landing attitude. The pilot gradually rounds out the flightpath to one that is parallel with, and within a very few inches above, the runway.
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 started ten (10) to twenty (20) feet above the ground. 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, the pilot used back-pressure to increase angle of attack (AOA) a rate that allows the airplane to continue settling slowly as forward speed decreases.
When the AOA is increased, the lift is momentarily increased, which decreases the rate of descent. Power normally is reduced to idle during the round-out, which decreases the airspeed.
The rate of rounding out must be proportionate to the rate of closure with the ground.
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. Visual cues used most are those related to changes in runway or terrain perspective. Focus direct central vision at a shallow downward angle from 10° to 15° toward the runway as the flare is initiated.
Maintaining the same viewing angle causes the point of visual interception with the runway to move progressively rearward as the airplane loses altitude. This is an important visual cue in assessing the rate of altitude loss.
Conversely, forward movement of the visual interception point indicates an increase in altitude and means that the pitch angle was increased too rapidly, resulting in an over flare.
Location of the visual interception point, in conjunction with assessment of flow velocity of nearby off-runway terrain, is used to judge when the wheels are just a few inches above the runway.
The similarity of appearance of height above the runway ahead of the airplane — in comparison to the way it looked when the airplane was taxied prior to takeoff — is also used to judge when the wheels are just a few inches above the runway.
To attain the proper landing attitude before touching down, the nose must travel through a greater pitch change when flaps are fully extended. The pitch attitude must be increased at a faster rate when full flaps are used, but always at a rate proportionate to the airplane's downward motion.
Once the actual process of rounding out is started, do not push the elevator control forward. If the round-out is inaccurate, pressure is either slightly relaxed or held constant. It may be necessary to advance the throttle slightly to prevent an excessive rate of sink or a stall, either of which results in a hard, drop-in type landing.
One hand should remain on the throttle throughout the approach and landing. A sudden and unexpected hazardous situation may require an immediate application of power.
The touchdown is the gentle settling of the airplane onto the landing surface. This is normally done with the engine idling and the airplane at minimum controllable airspeed. The airplane should touch down on the main gear at approximately stalling speed. The proper landing attitude is attained by application of whatever back-elevator pressure is necessary.
A common technique to making a smooth touchdown is to focus on holding the wheels of the aircraft a few inches off the ground as long as possible using back-elevator pressure while the power is smoothly reduced to idle.
When the wheels are within two or three feet off the ground, the airplane is still settling too fast for a gentle touchdown. The descent must be retarded by increasing back-elevator pressure. Since the airplane is already close to its stalling speed and is settling, this added back-elevator pressure only slows the settling instead of stopping it. The airplane should touch down in the proper landing attitude with the main wheels touching down first so that little or no weight is on the nose wheel.
After the main wheels make initial contact with the ground, back-elevator pressure is held for aerodynamic braking. This also holds the nose wheel off the ground until the airplane decelerates. As the airplane's momentum decreases, back-elevator pressure is gradually relaxed to allow the nose wheel to gently settle onto the runway.
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. Do not allow the airplane to touch down while turned into the wind or drifting.
The landing process is not complete until the airplane decelerates to the normal taxi speed during the landing roll, or until it has been brought to a complete stop when clear of the landing area.
Loss of directional control may lead to an aggravated, uncontrolled, tight turn on the ground.
The rudder controls the yawing of the airplane. Its effectiveness is dependent on 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.
Brakes can be used as an aid in directional control, when more positive control is required than can be obtained with rudder or nose wheel steering alone.
Maximum weight on the wheels after touchdown creates optimum braking performance. During deceleration, back-elevator pressure is applied without lifting the nose wheel off the runway. This enables directional control while keeping weight on the main wheels.
If the brakes are applied so hard that skidding takes place, braking becomes ineffective. Skidding is stopped by releasing the brake pressure.
If a wing starts to rise during the after-landing roll, aileron control is applied toward that wing to lower it. As the forward speed of the airplane decreases, the ailerons become less effective.
Back-elevator pressure is gradually relaxed to place weight on the nose wheel to aid in better steering.
When the airplane has exited the runway and come to a stop, perform the after-landing checklist.
Stabilized Approach Concept
A 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 requires 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, which is known as the aiming point. This is not where the airplane will touch down, but instead where the airplane would strike the ground if not flared for landing. Some float occurs during the flare, after which the airplane will touch down.
In a stabilized approach, the aiming point appears stationary. Objects in front of and beyond the aiming point will appear to move as the distance is closed. The pilot must use visual cues to accurately determine the true aiming point from any distance out on final approach. The pilot should be able to predict an overshoot or undershoot, and take corrective action if necessary. The pilot also should be able to predict the touchdown point to within a few feet.
In a stabilized approach, if the aiming point is moving down (away) from the horizon, then the true aiming point is farther down the runway. If the aiming point is moving up toward the horizon, the true aiming point is closer than perceived.
When viewed from the air, perspective causes the runway to appear as a trapezoid. The far end looks narrower than the approach end. The edge lines converge over the runway's total distance.
During a stabilized approach, the runway shape does not change. If the approach becomes shallow, the runway appears to shorten and become wider. If the approach is steepened, the runway appears to become longer and narrower
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. if the aiming point is short of the desired touchdown point, increase pitch attitude and power simultaneously, so that a constant airspeed is maintained. If the aiming point is farther down the runway than the desired touchdown point, steepen the glide path with a simultaneous decrease in pitch attitude and power. Airspeed remains constant.
Common errors in the performance of normal approaches and landings include.
A slip occurs when the bank angle of an airplane is too steep for the existing rate of turn. Intentional slips are used to dissipate altitude without increasing airspeed and/or to adjust airplane ground track during a crosswind.
Pilots flying airplanes that do not have flaps installed may use intentional slips to steepen their final approach course. Slips also are used when obstacles must be cleared during approaches to confined areas. A slip may be used in an emergency, such as where wing flaps are inoperative, or during forced landings.
A slip is a combination of forward and sideward movement. An airplane in a slip is flying sideways, resulting in a change in the direction that the relative wind strikes the airplane.
Intentional slips are characterized by a marked increase in drag, which makes it possible for an airplane to descend rapidly without an increase in airspeed.
Because most airplanes have positive static directional stability, they will compensate for slipping. An intentional slip, therefore, requires deliberate cross-controlling ailerons and rudder throughout the maneuver.
A sideslip is entered by lowering a wing and applying just enough opposite rudder to prevent a turn. The airplane's longitudinal axis remains parallel to the original flightpath. However, the airplane moves somewhat sideways toward the low wing. The amount of slip, and resulting sideways movement, is determined by the bank angle, with corresponding opposite rudder to prevent turning.
Sideslips are frequently used when landing with a crosswind to keep the aircraft aligned with the runway centerline while stopping any drift left or right of the centerline.
A forward slip is one in which the airplane's direction of motion continues the same as before the slip was begun. The wing on the side toward which the slip is to be made is lowered with ailerons. Simultaneously, the nose is yawed in the opposite direction with opposite rudder. The airplane's longitudinal axis is at an angle to its original flightpath.
The amount of forward slip, and therefore the sink rate, is determined by the bank angle. The steeper the bank is, the steeper the descent.
In both sideslips and forward slips, the point may be reached where full rudder is required to maintain heading even though the ailerons are capable of further steepening the bank angle. This is the practical slip limit. Beyond this point, any additional bank would cause the airplane to turn, even with full opposite rudder applied.
If there is a need to descend more rapidly beyond the practical slip limit, lowering the will increase the sink rate, although such also will increase airspeed. This will increase rudder effectiveness. At higher pitch attitudes, rudder effectiveness decreases.
Because of the location of the pitot tube and static vents, airspeed indicators in some airplanes may have considerable error when the airplane is in a slip. Pilots should recognize a properly performed slip by the attitude of the airplane, the sound of the airflow, and the feel of the flight controls.
If an airplane stalls while in a slip, it will display very little of the yawing tendency that causes a skidding stall to develop into a spin. It may tend to roll into a wings level attitude. In some airplanes, stall characteristics may even be improved.
Go-Arounds (Rejected Landings)
A pilot may decide to execute a go-around, also known as a rejected landing, due to one or more factors, including:
A go-around is not always the result of a poor approach, insufficient experience, or insufficient skill. A go-around is not an emergency procedure, but instead a normal maneuver that is also used in an emergency situation.
The flight instructor needs to emphasize early on, and the pilot must be made to understand, that the go-around maneuver is an alternative to any approach and/or landing.
The decision to go-around may arise at any point in the landing process. However, the most critical go-around is one started when very close to the ground. The maneuver is generally safer when the decision to go around is made sooner, rather than at the last possible moment. The go-around is only dangerous when delayed unduly or executed improperly.
Delay to go-around may be caused by latency — the belief that conditions are not threatening, and that a safe landing is assured.
Delay also may be caused by pride — the mistaken belief that the act of going around is an admission of failure.
The instant a pilot decides to go around, full or maximum allowable takeoff power must be applied smoothly and without hesitation and held until flying speed and controllability are restored. Carburetor heat is turned off to obtain maximum power.
A concern for quickly regaining altitude during a go-around produces a natural tendency to pull the nose up. The airplane executing a go-around must be maintained in an attitude that permits a buildup of airspeed well beyond the stall point before any effort is made to gain altitude or to execute a turn. In some circumstances, it is desirable to lower the nose briefly to gain airspeed.
Caution must be used in retracting the flaps when executing a go-around. Flaps should be retracted in small increments to allow time for the airplane to accelerate progressively as they are being raised. A sudden and complete retraction of the flaps could cause a loss of lift. Once the descent has been stopped, the landing flaps can be partially retracted or placed in the takeoff position.
In most airplanes, flaps should be retracted — at least partially — before retracting the landing gear. This is because flaps create more drag than landing gear. It's also because the landing gear may be necessary in the event of an inadvertent landing. Landing gear should only be retracted after a positive rate of climb is established.
Airplane control is critical during this high-workload phase of flight. When takeoff power is applied, application of maximum allowable power requires considerable control pressure to maintain a climb pitch attitude. This is because the airplane is trimmed for the approach. When climb airspeed and pitch attitude are attained, rough trim the airplane to relieve any adverse control pressures. Right rudder pressure must be increased to counteract left-turning propeller forces. The airplane must be held in the proper flight attitude regardless of the amount of control pressure that is required.
Ground effect can be an important factor in go-arounds, if the go-around is made close to the ground. Pilots can feel a false sense of security by the apparent cushion of air under the wings, which initially assists in the transition from an approach descent to a climb. This is "borrowed performance" that must be repaid when the airplane climbs out of the ground effect area. Pilots should only attempt to a climb out of ground effect after attaining a suitable airspeed.
Common errors in the performance of go-arounds include:
Crosswind Approach and Landing
There are two usual methods of accomplishing a crosswind approach and landing — the crab method and the wing-low method, also known as the sideslip method.
Although the crab method may be easier for the pilot to maintain during final approach, it requires a high degree of judgment and timing in removing the crab immediately prior to touchdown.
The wing-low method is recommended in most cases. A combination of both methods may be used.
Crosswind Final Approach
The crab method is executed by establishing a heading into the wind with the wings level so that the airplane's ground track remains aligned with the centerline of the runway. In this sense, the airplane's heading and track are notably different, similar to the sideways movement of a crab.
The crab angle is maintained until just prior to touchdown, when the longitudinal axis of the airplane must be aligned with the runway to avoid sideward contact of the wheels with the runway. The crab method also can be maintained until just before the round out is started, at which point the pilot smoothly changes to the wing-low method for the remainder of the landing.
The wing-low method compensates for a crosswind from any angle. It keeps the airplane's ground track and longitudinal axis aligned with the runway centerline throughout the final approach, round out, touchdown, and after-landing roll. This reduces the risk of side-loading the landing gear.
In the wing-low method, drift is controlled with aileron and the heading with rudder.
To use the wing-low method, align the airplane's heading with the centerline of the runway, note the rate and direction of drift, and promptly apply drift correction by lowering the upwind wing. To prevent the airplane from turning in the direction of the lowered wing, apply sufficient opposite rudder pressure. This will keep the airplane's longitudinal axis aligned with the runway.
When using the wing-low method in a strong crosswind, the upwind wing will be lowered a considerable amount, producing a stronger turning tendency and requiring more opposite rudder. If full opposite rudder does not prevent does not maintain centerline, the wind is too strong to safely land, and another option should be considered, such as an alternate runway or airport.
Crosswind Round-Out (Flare)
The crosswind correction must be maintained during the round-out. As the flight control surfaces become less effective at slower airspeeds, rudder and aileron deflections will gradually increase.
Keep the upwind wing down throughout the round-out. If the wings are leveled, touchdown will occur during drift, which will side-load the landing gear.
The crab method requires timely and accurate action, since the crab angle must be removed the instant before touchdown by applying rudder to align the airplane's longitudinal axis with its direction of movement. Failure to do this can result in severe side-loads.
The wing-low method requires the crosswind correction to be maintained throughout the round out. The touchdown made on the upwind main wheel. As the forward momentum decreases after initial contact, the downwind main wheel will to gradually settle onto the runway.
If the airplane's steerable nosewheel disconnects during flight, it should be aligned with the flightpath during landing. If the nosewheel does not disconnect during flight, corrective rudder pressure must be removed before the nose wheel touches down.
A well-executed wing-low landing will have a distinctive "one, two, three" cadence as all three wheels make contact with the runway in sequence — upwind main, downwind main, and then nosewheel.
Crosswind After-Landing Roll
Maintaining control on the ground is a critical part of the after-landing roll because of the weathervaning effect of the wind on the airplane.
During the landing roll, directional control must be maintained by the use of rudder or nose-wheel steering. Any rising of the upwind wing should be countered with aileron. Aileron application should be increased as the airplane slows to keep the upwind wing from rising in the crosswind. When the airplane is coming to a stop, the aileron control must be held fully toward the wind.
On roll-out, the relative wind comprises the natural wind and the headwind. The natural wind acts in the direction the air mass is traveling. The headwind is induced by the forward movement of the airplane, acting parallel to the direction of movement. As the airplane's forward speed decreases during the after landing roll, the headwind component diminishes, and the airplane is more apt to weathervane due to the natural wind (the crosswind component of the relative wind), which becomes more significant.
For each high-wing, tricycle-geared airplane, there is a cornering angle at which roll-over is inevitable. Cornering angle is the angular difference between the heading of a tire and its path. As little as 10° of cornering angle creates a side load equal to half the supported weight.
Maximum Safe Crosswind Velocities
Takeoffs and landings in certain crosswind conditions are inadvisable or even dangerous.
An FAA-certified airplane must be controllable — with no exceptional degree of skill or alertness on the part of the pilot — in 90° crosswinds up to a velocity equal to 0.2 Vso. Thus, an airplane with a stalling speed (in landing configuration) of 40 knots must be able to land in an 8-knot, 90° crosswind.
The headwind component and the crosswind component for a given situation is determined by reference to a crosswind component chart. The chart can be found in the POH/AFM. It is required on a placard in airplanes certificated after May 3, 1962.
Using the wind velocity and angle of the wind compared to the runway heading, pilots can consult the crosswind component chart and quickly determine if their airplane is suitable for landing in given conditions. Pilots must avoid operations in wind conditions that exceed the capability of the airplane.
Common errors in the performance of crosswind approaches and landings include:
Turbulent Air Approach and Landing
For landing in turbulent conditions, use a power-on approach at an airspeed slightly above the normal approach speed. This provides for more positive control of the airplane when strong horizontal wind gusts, or up and down drafts, are experienced.
To maintain control during an approach in turbulent air with gusty crosswind, use partial wing flaps, which will place the airplane in a higher-than-normal pitch attitude. This requires less of a pitch change to establish the landing attitude and touchdown. The higher airspeed ensures more positive control. However, excessive speed causes the airplane to float past the desired landing area.
Retard the throttle to idling position only after the main wheels contact the landing surface. In turbulent conditions, the sudden or premature closing of the throttle may cause a sudden increase in the descent rate that results in a hard landing.
One procedure is to use the normal approach speed plus one-half of the wind gust factors. Thus, If the normal speed is 70 knots, and the wind gusts are 15 knots, an increase of airspeed to 77 knots is appropriate. Always consult the POH/AFM for specific recommendations.
Touchdown is made with the airplane in approximately level flight attitude — enough to prevent the nose wheel from contacting the surface before the main wheels have touched the surface. After touchdown, avoid the tendency to apply forward pressure on the yoke. Avoid heavy braking until the wings are devoid of lift and the airplane's full weight is resting on the landing gear.
Commercial Pilot & Flight Instructor Test Questions
xxxxxxxxxxxx . (xxxx)