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ALC-34: Maneuvering: Approach and Landing
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Winds on Approach & Landing

 

As it is rare that the wind is blowing directly down the centerline of the runway, all pilots must be fully skilled in dealing with cross-wind approaches and landings.

 

Crosswind landings are a little more difficult to perform than crosswind takeoffs, mainly due to different problems involved in maintaining accurate control of the airplane while its speed is decreasing rather than increasing as on takeoff.

 

There are two usual methods of accomplishing a crosswind approach and landing—the crab method, and the wing-low (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, although a combination of both methods may be used.

 


 

The crab method is executed by establishing a heading (crab) toward the wind with the wings level so that the airplane’s ground track remains aligned with the centerline of the runway. This 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.

 

Diagram showing aircraft crabbed toward the wind, partially turned away from the runway centerline.

 

The wing-low (sideslip) method will compensate for a crosswind from any angle, but more important, it enables the pilot to simultaneously keep the airplane aligned with the runway centerline throughout the final approach, roundout, touchdown, and after-landing roll.

 

Align the airplane with the centerline of the runway, note the rate and direction of drift, and then promptly appliy drift correction by lowering the upwind wing.

 

 

Diagram of airplane aligned with runway while sideslipped with one wing lowered into the wind.

 

 

The amount the wing must be lowered depends on the rate of drift. When the wing is lowered, the airplane will tend to turn in that direction. It is then necessary to apply sufficient opposite rudder to keep the airplane aligned with the runway. In other words, the drift is controlled with aileron, and the heading with rudder.

 

 

 Illlustration of several phases of airplane on a crosswind approach and landing, showing up-wind wind being lowered until roundout.

 

 

In some airplanes, there may not be sufficient rudder travel available to compensate for the strong turning tendency caused by the steep bank. If the required bank is such that full opposite rudder will not prevent a turn, the wind is too strong to safely land the airplane. Since the airplane’s capability will be exceeded, the landing must be made on a more favorable runway either at that airport or at an alternate airport.

 

Flaps can and should be used during most approaches since they tend to have a stabilizing effect on the airplane.

 


 

Generally, the roundout can be made like a normal landing approach, but the application of a crosswind correction is continued as necessary to prevent drifting.

 

Since the airspeed decreases as the roundout progresses, the flight controls gradually become less effective. As a result, the crosswind correction being held will become inadequate. When using the winglow method, it is necessary to gradually increase the deflection of the rudder and ailerons to maintain the proper amount of drift correction.

 

Do not level the wings; keep the upwind wing down throughout the roundout. If the wings are leveled, the airplane will begin drifting and the touchdown will occur 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.

 


 

If the crab method of drift correction has been used throughout the final approach and roundout, 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.

 

If the wing-low method is used, the crosswind correction (aileron into the wind and opposite rudder) should be maintained throughout the roundout, and the touchdown made on the upwind main wheel.

 

In those airplanes having nosewheel steering interconnected with the rudder, the nosewheel may not be aligned with the runway as the wheels touch down because opposite rudder is being held in the crosswind correction. To prevent swerving in the direction the nosewheel is offset, the corrective rudder pressure must be promptly relaxed just as the nosewheel touches down.

 


 

Particularly during the after-landing roll, special attention must be given to maintaining directional control by the use of rudder or nose wheel steering, while keeping the upwind wing from rising by the use of aileron.

 

Characteristically, an airplane has a greater profile or side area behind the main landing gear, so the airplane will tend to turn or weathervane into the wind.

 

Wind acting on an airplane during crosswind landings is the result of two factors. One is the natural wind, which acts in the direction the air mass is traveling, while the other is induced by the movement of the airplane and acts parallel to the direction of movement. Consequently, a crosswind has a headwind component acting along the airplane’s ground track and a crosswind component acting 90° to its track. The resultant or relative wind is somewhere between the two components.

 

As the airplane’s forward speed decreases during the after-landing roll, the headwind component decreases and the relative wind has more of a crosswind component. The greater the crosswind component, the more difficult it is to prevent weathervaning.

 

Retaining control on the ground is a critical part of the after-landing roll, because of the weathervaning effect of the wind on the airplane.

 

While the airplane is decelerating during the afterlanding roll, more and more aileron is applied to keep the upwind wing from rising. Since the airplane is slowing down, there is less airflow around the ailerons and they become less effective. At the same time, the relative wind is becoming more of a crosswind and exerting a greater lifting force on the upwind wing. When the airplane is coming to a stop, the aileron control must be held fully toward the wind.

 


Takeoffs and landings in certain crosswind conditions are inadvisable or even dangerous. If the crosswind is great enough to warrant an extreme drift correction, a hazardous landing condition may result. Therefore, the takeoff and landing capabilities with respect to the reported surface wind conditions and the available landing directions must be considered.

Crosswind chart. Graph for calculating the ‘Danger Zone’ using wind angle & velocity data.

Before an airplane is type certificated by the Federal Aviation Administration (FAA), it must be flight tested to meet certain requirements. Among these is the demonstration of being satisfactorily 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. This means a wind speed of two-tenths of the airplane’s stalling speed with power off and landing gear/flaps down.

 

The headwind component and the crosswind component for a given situation can be determined by reference to a crosswind component chart. It is imperative that pilots determine the maximum crosswind component of each airplane they fly, and avoid operations in wind conditions that exceed the capability of the airplane.

Graph for calculating Crosswind Component.

 

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

 

  • Attempting to land in crosswinds that exceed the airplane’s maximum demonstrated crosswind component.
  • Inadequate compensation for wind drift on the turn from base leg to final approach, resulting in undershooting or overshooting.
  • Inadequate compensation for wind drift on final approach.
  • Unstabilized approach.
  • Failure to compensate for increased drag during sideslip resulting in excessive sink rate and/or too low an airspeed.
  • Touchdown while drifting.
  • Excessive airspeed on touchdown.
  • Failure to apply appropriate flight control inputs during rollout.
  • Failure to maintain direction control on rollout.

 


 

Power-on approaches at an airspeed slightly above the normal approach speed should be used for landing in turbulent air. This provides for more positive control of the airplane when strong horizontal wind gusts, or up and down drafts, are experienced.

 

To maintain good control, the approach in turbulent air with gusty crosswind may require the use of partial wing flaps. With less than full flaps, the airplane will be in a higher pitch attitude. Thus, it will require less of a pitch change to establish the landing attitude, and the touchdown will be at a higher airspeed to ensure more positive control.

 

An adequate amount of power should be used to maintain the proper airspeed and descent path throughout the approach, and the throttle retarded to idling position only after the main wheels contact the landing surface.

 

After touchdown, the pilot should avoid the tendency to apply forward pressure on the yoke as this may result in wheelbarrowing and possible loss of control. The airplane should be allowed to decelerate normally, assisted by careful use of wheel brakes.