Autopilot system operation with a pitch trim malfunction is considered to be what?

The operation of the autopilot system with a pitch trim malfunction is classified as prohibited. This is because the autopilot relies on the pitch trim system to maintain the aircraft's attitude and perform its functions effectively. If there is a malfunction in the pitch trim, it can lead to improper control, increased workload for the pilot, and potential loss of aircraft control. Therefore, for safety reasons, operating the autopilot under such conditions is not allowed. This classification helps ensure that pilots avoid situations that could compromise the safety and stability of the aircraft during flight.