The fuel-optimal control problem in aeroassisted non-coplanar orbital transfer is addressed. The equations of motion for the atmospheric manoeuvre are non-linear and the optimal )nominal) trajectory and control are obtained. In order to follow the nominal trajectory under actual conditions, a neighbouring optimum guidance scheme is designed using linear quadratic regulator theory for onboard real-time implementation. One of the state variables is used as the independent variable in preference to the time. The weighting matrices in the performance index are chosen by a combination of a heuristic method and an optimal modal approach. The necessary feedback control law is obtained in order to minimize the deviations from the nominal conditons. The results are presented to a typical aeroassisted non-coplanar orbital transfer problem.