While it is usually preferable to take off directly into the wind whenever possible or practical, there are many instances when circumstances or judgment indicate otherwise. Therefore, the pilot must be familiar with the principles and techniques involved in crosswind takeoffs, as well as those for normal takeoffs.
The manufacturers maximum wind and crosswind component in the POH should not be exceeded. The following procedures are for operation within these limitations.
The technique used during the initial takeoff roll in a crosswind is generally the same as used in a normal takeoff, except that the pilot must control the wing’s tendency to weathervane into the wind during the takeoff roll. Additionally, the pilot should keep the WSC aircraft on the ground and accelerate to a higher speed before rotation.
As the aircraft is taxied into takeoff position, it is essential that the windsock and other wind direction indicators be checked so that the presence of a crosswind may be recognized and anticipated. During taxi and takeoff, the windward side of the wing needs to be slightly lowered so as to not let the wind get under it and lift it off; but not too low or additional pilot effort is required and unnecessary stress is placed on the carriage.
The crosswind takeoff is performed similar to the normal takeoff except two different techniques are utilized. First, as the WSC aircraft accelerates and the pilot steers the carriage straight down the runway, the wing will want to weathervane into the wind. This creates stress on the wing attachment to the carriage, the carriage mast, and the keel of the carriage. Therefore, the pilot must hold the wing control bar straight to the carriage which requires significant force and muscle. Second, the pilot must accelerate to a higher speed before rotating to account for the crosswind component. This requires the nose to be held down to prevent the WSC from popping off the ground before the higher airspeed is obtained.
Since this technique requires the pilot to muscle the wing rather than using a light touch, it requires a mastery of the normal takeoff before crosswind takeoffs should be attempted. As the WSC aircraft accelerates down the runway, the forces of the wing try to weathervane it into the wind and the nose raises up to trim. The wing should be held straight with the nose down until rotation where the wing is held straight and the nose raised.
Rotation and Lift-Off
When a faster rotation speed than normal takeoff is achieved, a smooth but quicker push out to rotate is desired to get the front and rear wheels into the air quickly, avoiding any tendency to remain on the rear wheels. After lift-off, the WSC automatically rotates into the relative wind since momentum is straight down the runway and the characteristics of the wing point it directly into the relative wind. The WSC sets up the wind correction angle (or crab angle as it is also called) as it lifts off. [Figure 7-7]
After lift-off, the WSC aircraft is pointed toward the wind and the ground track is headed straight down the runway centerline. Maintain this ground track aligned directly down the centerline of the runway “crabbing” into the wind. Crabbing is a term used to adjust flight controls into the crosswind to maintain a straight ground track while the WSC is pointed towards the wind, as seen in Figure 7-8. To maintain the ground track it is important to look straight down the runway centerline and steer to stay on that ground track even though the WSC is pointed towards the wind and not directly down the runway. Because the force of a crosswind may vary markedly within a few hundred feet of the ground, frequent checks of actual ground track should be made [Figure 7-7] or the WSC could drift to the side if the wind correction angle is not maintained. The remainder of the climb technique is the same used for normal takeoffs and climbs maintaining the proper ground track with the proper wing correction angle/crab angle. [Figure 7-8]
In addition to normal takeoffs, additional common errors in the performance of crosswind takeoffs are:
- Letting the windward side of the wing get too high.
- Allowing the wing to weathervane into the wind during the takeoff roll.
- Not obtaining additional speed before rotation.
- Too slow of a rotation during lift-off.
- Inadequate drift correction after lift-off.