a) determining a control vector, τ, for the aircraft, τ=(L M N F)^T, components of which represent control torques L, M, and N of the aircraft around a roll axis, a pitch axis, and a yaw axis, respectively, and a total thrust, F;

b) approximating an existing four-dimensional control volume, D, of the aircraft by a four-dimensional ellipsoid, E, axes of which represent the control torques, L, M, and N, of the aircraft and the total thrust, F;

c) determining a normalized control vector, τ_ind=(L_ind M_ind N_ind F_ind)^T for the aircraft, using axis dimensions, L_max, M_max, N_max, F_max, of the ellipsoid, L_ind, M_ind, N_ind, and F_ind representing a normalized control torque of the aircraft around the roll axis, a normalized control torque of the aircraft around the pitch axis, a normalized control torque of the aircraft around the yaw axis, and a normalized total thrust, respectively;

d) outputting at least the normalized control vector, τ_ind, for determining a permissible flight maneuver in at least one dimension of the four-dimensional control volume; and

e) controlling, using a flight controller or flight control device for the aircraft, the number of propulsion units of the aircraft to perform the permissible flight maneuver based at least in part on the normalized control vector, τ_ind.