Physical Science - Other

Landing in Wind Effects and Cross Winds

Larry Wiggins's image for:
"Landing in Wind Effects and Cross Winds"
Image by: 

All pilots look forward to the day their instructor gets out of the airplane and tells the student that he is ready for that first solo flight. As the student taxis back to the runway, he is planning his flight and already apprehensive about the most important phase of this flight, the solo landing. Landing of the airplane is the maneuver that requires the most training and creates the most apprehension for the pilot.

In an ideal landing situation, the wind blows directly down the runway and the pilot can land faced into that wind. Landing speeds are dictated by the type of airplane and should be nearly the same for each landing. Since an airplane measures speed in relation to the wind, heading into the wind reduces the speed over the ground by the same amount as the speed of the wind. With the slower ground speed, there is a shorter distance needed for the landing rollout.

The wind does not always cooperate and blow straight down the runway. If the wind direction comes from a side of the runway it is called a crosswind. A crosswind can cause the airplane to drift to the side or off the runway. A crosswind can be dealt with in a several manners. Some airports assist the pilots in dealing with crosswinds by decreasing the chance of their occurrence by constructing multiple runways and orienting them in the direction of the prevailing winds.

Since it is impossible to construct runways in every direction, most landings will have at least a small crosswind component. The crosswind component is the equivalent wind at right angles to the runway. The wind is thought of as the sum of two vectors. One vector is parallel to the runway and the other vector is perpendicular to the runway. The wind component parallel to the runway will decrease the ground speed. The crosswind component will blow the airplane across the runway.

For a wind that is only a few degrees from the direction of the runway, the crosswind component is small and the component parallel to the runway is large. The crosswind component increases until the wind direction is ninety degrees to the runway. That crosswind component is equal to the speed of the wind with a zero component parallel to the runway. Each pilot's operating handbook should contain the maximum approved crosswind component for that type of airplane.

There are two methods of dealing with the crosswind. One method lowers the wing into the wind and uses the rudder to keep the airplane's ground track down the extended runway centerline. When the airplane touches down, the wheel on the side of the airplane into the wind will touch first. The other method uses a "crab" angle on the final approach. The pilot sets a course directed into the wind knowing that the wind will blow the airplane back so that the ground course is in line with the runway centerline. The pilot straightens the crab angle out just prior to touchdown and lands with a wing low as in the first procedure.

As you may surmise, each crosswind procedure requires practice to perfect. The pilot must be aware of the speed of the airplane and its ground track to bring the airplane to the point of landing. The pilot should know the plane's and his own limitations. There may be times that the prudent landing may not be at the originally planned destination, but at one where the crosswind conditions are more favorable.
ur article here

More about this author: Larry Wiggins

From Around the Web