Effects of wind on landing

The above picture looks deceptively simple in that we have ignored any need for lateral control. Ideally the aircraft should be landing directly into the wind, but unfortunately, although airports are built so that the runway is aligned with the prevailing wind wherever possible, the weather is seldom completely obliging! Because of this it is necessary for the side wind to be allowed for dur­ing the approach so that the flightpath remains aligned with the runway.

This can be achieved in one of two ways. In the first of these ways the aircraft is flown with one wing low and the rudder is used to prevent a turn developing. In this way a steady sideslip can be used to counteract the side wind while keeping the aircraft aligned with the runway. In the second method the aircraft heading is altered to compensate for the wind and the resulting mis­alignment with the runway is corrected, largely by rudder control, just before touch-down in a process known as ‘kicking off drift’. These two methods are illustrated in Figs 13.9 and 13.10.

Sidewards drift is not the only problem posed by the wind on landing. Because the earth has its own, rather thick, boundary layer, the wind speed

will reduce rapidly as the aircraft height reduces. This is known as ‘wind shear’ (Fig. 13.11). Not only this, there may be substantial gusts as well. This will obviously complicate the process of flying an accurate rate of descent on the glide. Also, if the air speed has been allowed to come too close to the stall there is a real danger of a stall being initiated.