Abstract: A fuel-optimal four dimensional (4D) guidance algorithm is presented in this paper. With the aid of the proposed algorithm, an optimal flight trajectory can be calculated on line. Such an optimal flight path can meet both the fuel savings and arri val time requirements. In the paper, simulation results also show that the algorithm mentioned above is really satisfactory from the engineering point of view. Since not only the computation time is reduced in comparison with other algorithms, but the precision is also high. The work done in this paper is a necessary step for the implementation of on-board 4D Flight Management System (FMS).

Key words: Flight Management System, four-dimensional guidance, fuel-optimal tra jectory, fibonacci search technique