When should the "Flap Asymmetry" check be performed?

The "Flap Asymmetry" check is performed during preflight checks to ensure that the flaps are functioning correctly and are set to the proper configuration for flight. This check is crucial because any asymmetry in the flap operation could significantly affect the aircraft's handling characteristics, especially during takeoff and landing.

Conducting this check before flight allows pilots to identify any issues with the flap system early on, thereby preventing potential problems during crucial phases like takeoff or landing where flap performance is critical for safe operation. It ensures that pilots can address and rectify any discrepancies before they become a factor in the flight, increasing safety and operational readiness.

Other timings, such as after takeoff or prior to landing, while relevant for other checks, do not serve the primary purpose of the flap asymmetry check, which is to ensure all systems are functioning correctly before the flight begins.