As a drift or drift ( holländ. drijven = float ) refers to a lateral displacement ( drift ) of vessels or aircraft, ie a deviation from the intended course.
S under the drift angle is meant the angle between the longitudinal axis or direction of movement and the course angle. The sign is opposite to the transverse velocity component defined:
( = Transverse velocity, = longitudinal speed )
Is caused by the drift of aircraft crosswind and gusts.
For sailplanes and powered aircraft slow drift can be in strong crosswind 30 ° and more. Because of the clarity of the effect can lengthen the course but freiäugig - even without navigational instruments - by " Provision " correct well. The short-term effect of gusts can be " stabilized " with the turn and bank indicator.
It is caused drift in ships by side wind and wave. The influence of flow (eg, ocean current or tidal current ) is not included in the drift and is considered as a current transfer separately.
For vessels counteracts a large lateral area and the shape of the underwater hull of the drift. In sailing ships, the largest drift occurs at rate on the wind. In course half the wind drift is already much lower, barely present in course quartering wind.
Correction of drift
For larger aircraft and ships drift is generally predicted from weather data and in the choice of the tax rate in advance account ( crab angle ). This ensures that the course over ground nearly lead to the desired goal. For vessels here also the flow is taken into account.
The situation may drift during the landing of small and large aircraft be: to avoid damage to the landing gear, the heading, aligned parallel to the runway in strong winds or gusts, just before touchdown.