Piloted Simulation Evaluation of a Model-Predictive Automatic Recovery System to Prevent Vehicle Loss of Control on Approach

Abstract This paper describes a model-predictive automatic recovery system for aircraft on the verge of a loss-of-control situation. The system determines when it must intervene to prevent an imminent accident, resulting from a poor approach. It estimates the altitude loss that would result from a go-around maneuver at the current flight condition. If the loss is projected to violate a minimum altitude threshold, the maneuver is automatically triggered. The system deactivates to allow landing once several criteria are met. Piloted flight simulator evaluation showed the system to provide effective envelope protection during extremely unsafe landing attempts. The results demonstrate how flight and propulsion control can be integrated to recover control of the vehicle automatically and prevent a potential catastrophe. Introduction On July 6, 2013, an Asiana Airlines Boeing 777 on final approach to San Francisco International Airport (SFO) came in too low and too slow. Shortly before reaching the runway threshold, the throttles moved forward (Ref. 1) to increase power and thus airspeed, possibly in an attempt to perform a go-around. However, before the additional power could have an effect, the aircraft pitched up and the tail section hit the seawall at the end of the runway. The impact broke off the empennage and landing gear, and the craft skidded, spinning and burning, down the runway. On this fateful flight, the aircraft was below glideslope and going too slowly during approach (Ref. 2). A common method of maintaining glideslope is for the pilot to manipulate pitch. Directed by the glideslope indicator, the pilot pulls the nose up if the craft is too low, and pushes the nose down if it is too high. Simultaneously, the pilot should be monitoring and maintaining airspeed by adjusting the throttle