When should the turn from downwind to base leg occur?

The turn from downwind to base leg should occur when the intended touchdown point is approximately 45 degrees behind the wing. This approach allows for a safe and effective transition in the traffic pattern. Establishing the turn at this point helps ensure that the pilot is positioned correctly for a stable approach to the runway, allowing for adequate spacing and alignment with the runway.

Making the turn at 45 degrees behind the wing provides a clear visual reference for the pilot, helping them gauge their descent and approach angle. This technique is essential for managing airspeed, descent rate, and avoiding potential conflicts with other traffic in the pattern. It ensures that the aircraft is well-set up for the final approach, contributing to a smoother landing.

Choosing alternative moments to initiate the turn, such as passing the threshold of the runway, would not ensure proper spacing and could lead to a compromised approach. Waiting for a specific descent rate or entering the pattern at a low speed are also not appropriate triggers for the turn, as they do not account for the necessary visual framing and situational awareness required for a safe landing approach.