Piloting Strategies for Controlling a Transport Aircraft After Vertical-Tail Loss

In a number of instances, aircraft that have suffered in-flight damage to their airframe or control system were brought safely to the ground using unconventional means of control. The success in these cases depended greatly on the pilot having had some exposure to unconventional control strategies. Control strategies are considered for cases of aircraft with damage only to the primary control system, as well as cases in which the vertical tail is lost. The piloting strategies are developed using optimal control theory, which optimizes the control law for a desired maneuver and a chosen aircraft configuration. The results show that, despite the loss of the primary control system or of the vertical tail, control of the aircraft is often possible, although it requires the use of unconventional control strategies, in particular, of differential thrust. Especially in the case without a vertical tail, the maneuver in which adverse yaw induces a rolling moment opposite to the intended yaw direction is somewhat surprising and, initially, counterintuitive.