Practical considerations in optimal flight management computations

The relationships between cost index, speed, flight time, fuel burn, and wind are investigated via simulations of flight of a DC-10 aircraft, as controlled by a flight management computer system (FMCS), over a representative 1000 NM flight plan. In this context, a two-part procedure is described for achieving minimum total flight cost; that is, direct operating cost plus arrival error cost. First the optimum cost index and the associated optimum arrival time (which sometimes turns out to be the scheduled arrival time) are sought. A simple method for fine tuning the speed to achieve the desired arrival time is then described. The methods are practical to incorporate in the FMCS.