Simmon, D. A. | Engineering Papers

NASA NTRS1986

Algorithm for Fuel-Conservative Airplane Descents

Federal Aviation Administration implementing automated, time-based metering form of air-traffic control (ATC) with profile-descent procedures for arrivals into terminal area. Measures provide fuel savings by matching arrival of airplanes to airport acceptance rate through time-control computations and allowing pilot to descend at his discretion from cruise altitude to designated metering-fix altitude in idle-thrust clean configuration. Airborne descent algorithm developed compatible with time-based metering and profile-descent procedures and designed to improve accuracy of delivering airplane during fuel-efficient descent to metering fix at time designated by the ATC system.

Knox, C. E.↗

NASA NTRS1985

Planning fuel-conservative descents in an airline environmental using a small programmable calculator: Algorithm development and flight test results

A simple, airborne, flight-management descent algorithm was developed and programmed into a small programmable calculator. The algorithm may be operated in either a time mode or speed mode. The time mode was designed to aid the pilot in planning and executing a fuel-conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The speed model was designed for planning fuel-conservative descents when time is not a consideration. The descent path for both modes was calculated for a constant with considerations given for the descent Mach/airspeed schedule, gross weight, wind, wind gradient, and nonstandard temperature effects. Flight tests, using the algorithm on the programmable calculator, showed that the open-loop guidance could be useful to airline flight crews for planning and executing fuel-conservative descents.

Knox, C. E.↗