FLIGHT TESTS OF NOISE ABATEMENT APPROACHES FOR ROTORCRAFT USING DIFFERENTIAL GPS GUIDANCE

The NASA/Army Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) UH-60A Black Hawk helicopter was used to test the feasibility of using operational techniques to alleviate helicopter noise during approach to landing. Decelerating approaches were flown using multi-segment glidepaths. The approaches were designed to avoid flight conditions known to generate noise due to blade-vortex-interaction (BVI). A Local Differential Global Positioning System (LDGPS) was used for precision navigation, and guidance calculations were performed in an onboard computer. Steering commands were presented to the pilot using the existing electromechanical flight instruments of the UH-60A. Operational aspects of the noise abatement approaches were evaluated by pilots from NASA, FAA, and the helicopter industry. The methodology used to design the noise abatement trajectories is described, and navigation system and flight technical error data are reported.