Base Leg

The base leg is a segment of the standard traffic pattern (circuit) flown at right angles to the runway, connecting the downwind leg to the final approach. During the base leg, the pilot begins the descent toward the runway and adjusts speed and configuration (extending flaps, reducing power) in preparation for landing.

The turn from downwind to base is typically initiated when the runway threshold is approximately 45 degrees behind the wing. The base leg is relatively short, and the pilot must judge the timing of the turn to final carefully to establish a stabilized approach. Overshooting the turn from base to final is a common contributor to loss-of-control accidents in general aviation.