Evaluation of a pilot interface with an automated Nap-of-the-Earth rotorcraft system

An effective pilot interface with the Ames Automated NOE (nap-of-the earth) Guidance and Control System (ANGCS) was evaluated in a versatile, workstation-based piloted simulation. The interface allows the pilot to fly the vehicle with a two-degree-of-freedom control stick while maintaining adequate control of the desired flight path, and with added OA (obstacle avoidance) protection. This evaluation of the PDG (pilot-directed guidance) concept resulted in the development and refinement of display symbology that greatly enhanced overall pilot acceptance. Two experiments designed to tune the ANGCS/PDG system for optimal pilot acceptability were successfully completed. The first resulted in an optimal range for the prediction time, as a function of velocity, that governs the look-ahead time response of the automatic OA subsystem. The second resulted in pilot selection of a desirable azimuthal search domain that forces vertical maneuvering under conditions otherwise requiring excessive lateral deviation from the nominal course. Initial pilot reaction suggests that the PDG interface concept is more acceptable to pilots than past implementations involving pilot override of fully automatic NOE hands-off systems. This evaluation demonstrated the potential for the PDG interface to reduce pilot OA workload while allowing for continuous pilot autonomy over the general guidance of the vehicle