22-10-2012, 04:15 PM
Design and Testing of a Low Noise Flight Guidance Concept
ABSTRACT
A flight guidance concept was developed to assist in flying continuous descent approach (CDA) procedures designed to
lower the noise under the flight path of jet transport aircraft during arrival operations at an airport. The guidance consists of
a trajectory prediction algorithm that was tuned to produce a high-efficiency, low noise flight profile with accompanying
autopilot and flight display elements needed by the flight control system and pilot to fly the approach. A key component of
the flight guidance was a real-time display of energy error relative to the predicted flight path. The guidance was integrated
with the conventional Flight Management System (FMS) guidance of a modern jet transport airplane and tested in a high
fidelity flight simulation. A charted arrival procedure, which allowed flying conventional arrivals, CDA arrivals with standard
guidance, and CDA arrivals with the new low noise guidance, was developed to assist in the testing and evaluation of the low
noise guidance concept. Results of the simulation testing showed the low noise guidance was easy to use by airline pilot test
subjects and effective in achieving the desired noise reduction. Noise under the flight path was reduced by at least 2 decibels
in Sound Exposure Level (SEL) at distances from about 3 nautical miles out to about 17.5 nautical miles from the runway,
with a peak reduction of 8.5 decibels at about 10.5 nautical miles. Fuel consumption was also reduced by about 17% for the
LNG conditions compared to baseline runs for the same flight distance. Pilot acceptance and understanding of the guidance
was quite high with favorable comments and ratings received from all test subjects.