Four-dimensional fuel-optimal guidance in the presence of winds

The generation of optimal trajectories from cruise altitude to 10,000 ft for a typical commercial jet transport shows that the optimal absorption of delay in arrival time requires speed reduction in conjunction with altitude excursion (the latter not attempted before). Multiple regression methods are used to develop drag and fuel flow models which are smoother and more compact than those of any previous investigation. The concept of optimal cruise descent is introduced and optimal results are compared with suboptimal strategies of constant Mach number/Calibrated Airspeed (CAS) descent and constant flight path angle descent. Finally, wind effects are analyzed, and the cost of delay as a function of wind condition is presented, followed by the effects of wind on the constant flight path angle descent.