Piloted Simulator Evaluation of Safe Flight Envelope Display Indicators for Loss of Control Avoidance

Abstract

In recent studies, it has been observed that loss of control in flight is the most frequent primary cause of accidents. One of the technologies that will significantly reduce the risk of loss of control accidents is onboard safe flight envelope estimation. An efficient method for estimating the safe flight envelope for impaired aircraft has been implemented and evaluated in piloted simulations. This modular method is based on a physical approach. The aerodynamic system parameters are estimated from realistic noisy sensor measurements based on a probabilistic approach. These parameters are then used for efficient model-based computations of the trim envelope as a set of equilibrium points that can be attained by means of admissible inputs. The safe maneuverability limitations are extended beyond the trim envelope through a robust reachability analysis derived from an optimal control formulation. These trim and maneuvering envelope limits can be used for multiple purposes. For example, they can be conveyed to the flight crew in an intuitive way by incorporating this information in the primary flight display. These display features have been evaluated in the Advanced Concepts Flight Simulator at Ames Research Center as part of a larger research initiative. Commercial airline crews flew multiple challenging approach and landing scenarios in a relevant environment. Results show that the additional display features contribute significantly to flight crew awareness and avoiding loss of control in flight.