Evaluation of a sliding mode fault-tolerant controller for the El Al incident

This paper presents piloted flight simulator results associated with the El Al flight 1862 scenario, using a modelreferencebased sliding mode control allocation scheme for fault-tolerant control. The proposed controller design was carried out without any knowledge of the type of failure and in the absence of any fault detection and isolation strategy. This is motivated by the fact that the flight crew were unaware of the losses of the right engines. For this reason, the control allocation scheme proposed uses (fixed) equal distribution of the control signals to all actuators (for both nominal situations and when a fault or failure occurs). This paper analyzes the scheme and determines the conditions under which closed-loop stability is retained. The results represent the successful realtime implementation of the proposed controller on a flight simulator, configured to represent a B747 aircraft. The evaluation results from the experienced pilots show that the proposed controller has the ability to position the aircraft for landing, both in a nominal scenario and in the El Al failure scenario. It is also shown that actuator faults and failures that occurred during the El Al incident can be handled directly without reconfiguring the controller