Abstract: The calculation of equilibrium points for a nonlinear decoupled system is discussed.Three modes of decoupling controls for aircraft maneuvers are studied with the decoupling control theory based on the differential geometry control theory.Two types of agility maneuvers and three basic modes \%A\-n,α\-1 \%and\% α\-2\% of direct lift control are realized by the three nonlinear decoupling control modes.Simulation results show that the decoupling control modes can realize the direct lift control modes and the agility maneuvers thoroughly.The study provides a new theoretical approach to investigate aircraft agility and direct force control.

Key words: differential geometry approach, nonlinear decoupling control, no nlinear flight dynamics, air craftagility, direct force control