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ALC-34: Maneuvering: Approach and Landing
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Normal Landing

The roundout is a slow, smooth transition from a normal approach attitude to a landing attitude, gradually rounding out the flight path 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 roundout or flare should be started and be a continuous process until the airplane touches down.

 

As the airplane reaches a height above the ground where a timely change can be made into the proper landing attitude, back-elevator pressure should be gradually applied to slowly increase the pitch attitude and angle of attack.

 

The angle of attack should be increased at a rate that will allow the airplane to continue settling slowly as forward speed decreases.

 

8-06_Chg_Angl_Roundout.JPG

 

When the angle of attack is increased, the lift is momentarily increased, which decreases the rate of descent.  During the roundout, the airspeed is being decreased to touchdown speed while the lift is being controlled so the airplane will settle gently onto the landing surface.

 

The roundout should be 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 roundout is executed depends on the airplane’s height above the ground, the rate of descent, and the pitch attitude. A roundout 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. 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.

 

Direct central vision at a shallow downward angle of from 10° to 15° toward the runway as the roundout/flare is initiated. Maintaining the same viewing angle causes the point of visual interception with the runway to move progressively rearward toward the pilot as the airplane loses altitude. This is an important visual cue in assessing the rate of altitude loss.

 

8-07_Look_Rwy_Shlw_Angl.JPG

 

Once the rounding out is started, the elevator control should not be pushed forward. If too much back-elevator pressure has been exerted, this pressure should be either slightly relaxed or held constant, depending on the degree of the error. It may be necessary to advance the throttle slightly to prevent an excessive rate of sink, or a stall.

 

Form the habit of keeping one hand on the throttle throughout the approach and landing, should a sudden and unexpected hazardous situation require an immediate application of power. 

 

The roundout and touchdown should be made with the engine idling, and the airplane at minimum controllable airspeed, so that the airplane will touch down on the main gear at approximately stalling speed.

 

Some pilots may try to force or fly the airplane onto the ground without establishing the proper landing attitude. The airplane should never be flown on the runway with excessive speed.

 

In most cases, when the wheels are within 2 or 3 feet off the ground, the airplane will still be settling too fast for a gentle touchdown; therefore, this descent must be retarded by further back-elevator pressure. Since the airplane is already close to its stalling speed and is settling, this added back-elevator pressure will only slow up the settling instead of stopping it.

 

At the same time, it will result in the airplane touching the ground in the proper landing attitude, and the main wheels touching down first so that little or no weight is on the nose wheel.

 

8-08_Well_Exec_Roundout.JPG

 

After the main wheels make initial contact with the ground, back-elevator pressure should be held to maintain a positive angle of attack for aerodynamic braking, and to hold the nose wheel off the ground until the airplane decelerates.

 

As the airplane’s momentum decreases, back-elevator pressure may be gradually relaxed to allow the nose wheel to gently settle onto the runway.

 

It is extremely important that the touchdown occur with the airplane 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.

 

The landing process must never be considered complete until the airplane decelerates to the normal taxi speed during the landing roll. Many accidents have occurred as a result of pilots abandoning their vigilance and positive control after getting the airplane on the ground.

 

You must be alert for directional control difficulties immediately upon and after touchdown due to the ground friction on the wheels.

 

The rudder serves the same purpose on the ground as it does in the air—it controls the yawing of the airplane. The effectiveness of the rudder is dependent on the speed of the airplane. As the speed decreases and the nosewheel has been lowered to the ground, the steerable nose provides more positive directional control.

 

The brakes may also be 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 should slide 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 should not 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 deceleration, the nose may be pitched down by braking

 

Careful application of the brakes can be 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.

 

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.

 

The ailerons serve the same purpose on the ground as they do in the air—they change the lift and drag components of the wings. During the after-landing roll, they should be used to keep the wings level in much the same way they were used in flight. If a wing starts to rise, aileron control should be applied toward that wing to lower it.

 

After the airplane is on the ground, back-elevator pressure may be gradually relaxed to place normal weight on the nosewheel to aid in better steering.

 

Once the airplane has slowed sufficiently and has turned on to the taxiway and stopped, retract the flaps and clean up the airplane.

 


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.

 

An airplane descending on final approach at a constant rate and airspeed will be traveling in a straight line toward a spot on the ground ahead. This spot will not be the spot on which the airplane will touch down, because some float will inevitably occur during the roundout (flare).

 

The point toward which the airplane is progressing is termed the “aiming point.” 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.

 

When moving straight ahead toward an object, it appears to be stationary. This is how the aiming point can be distinguished — it does not move.

8-09_Stabil_Appr.JPG

One of the most important skills a student 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, you will not only be able to determine if the glide-path will result in an undershoot or overshoot, but, taking into account float during roundout, you will be able to predict the touchdown point to within a very few feet.

 

When the airplane is established on final approach, the shape of the runway image presents clues as to what must be done to maintain a stabilized approach to a safe landing.

 

A runway, obviously, is normally shaped in the form of an elongated rectangle. When viewed from the air during the approach, the runway appears shaped like a trapezoid, with the far end looking narrower than the approach end. If the airplane continues down the glide-path at a constant angle (stabilized), the image the pilot sees will still be trapezoidal but of proportionately larger dimensions. In other words, during a stabilized approach the runway shape does not change.

 

8-10_Rwy_Shape_Stab_Appr.JPG

 

If the approach becomes shallower, however, the runway will appear to shorten and become wider. Conversely, if the approach is steepened, the runway will appear to become longer and narrower.

 

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. 

8-11_Chg_Rwy_Shape.JPG

Common errors in the performance of normal approaches and landings are:

 

• Inadequate wind drift correction on the base leg.

• Overshooting or undershooting the turn onto final approach resulting in too steep or too shallow a turn onto final approach.

• Flat or skidding turns from base leg to final approach as a result of overshooting/inadequate wind drift correction.

• Poor coordination during turn from base to final approach.

• Failure to complete the landing checklist in a timely manner.

• Unstabilized approach.

• Failure to adequately compensate for flap extension.

• Poor trim technique on final approach.

• Attempting to maintain altitude or reach the runway using elevator alone.

• Focusing too close to the airplane resulting in a too high roundout.

• Focusing too far from the airplane resulting in a too low roundout.

• Touching down prior to attaining proper landing attitude.

• Failure to hold sufficient back-elevator pressure after touchdown.

• Excessive braking after touchdown.

 


Intentional slips are used to dissipate altitude without increasing airspeed, and/or to adjust airplane ground track during a crosswind. They are especially useful in forced landings, and 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.

 

An airplane in a slip is in fact flying partly sideways. 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.

 

A “sideslip” is entered by lowering a wing and applying just enough opposite rudder to prevent a turn.

 

8-12_Sideslip.JPG

 

 

The amount of slip, and therefore the rate of sideward movement, is determined by the bank angle. The steeper the bank — the greater the degree of slip. As bank angle is increased, additional opposite rudder is required to prevent turning.

 

A “forward slip” is one in which the airplane’s direction of motion continues the same as before the slip was begun. Assuming the airplane is originally in straight flight, the wing on the side toward which the slip is to be made should be lowered by use of the ailerons. Simultaneously, the airplane’s nose must be yawed in the opposite direction by applying opposite rudder so that the airplane’s longitudinal axis is at an angle to its original flightpath.

 

8-13_Fwd_Slip.JPG

 

The degree to which the nose is yawed in the opposite direction from the bank should be such that the original ground track is maintained. In a forward slip, the amount of slip, and therefore the sink rate, is determined by the bank angle. The steeper the bank— the steeper the descent.

 

Discontinuing a slip is accomplished by leveling the wings and simultaneously releasing the rudder pressure while readjusting the pitch attitude to the normal glide attitude.

 

Because of the location of the pitot tube and static vents, air speed indicators in some airplanes may have considerable error when the airplane is in a slip. The pilot must be aware of this possibility and recognize a properly performed slip by the attitude of the airplane, the sound of the airflow, and the feel of the flight controls.