double track error

A navigational technique for regaining the desired track. This technique is followed provided the aircraft has not passed the halfway point along the leg being flown. The course is altered toward the desired track by twice the track error (TE). This means that the closing angle (CA) will be equal to the track error. At the point where the new track intercepts the desired track, a second alteration of heading, equal to TE but opposite to the first alteration of the heading, is required to fly the aircraft down the regained track. Since the TE and CA are identical, the distance from the start of the leg to the point of the first altered heading is the same as from there to the point of regaining the desired track, and the time to fly each leg will be the same.

Retaining the desired track by the double track error method.