Only specific aircraft features this "instability" and thus the maneuver can only be performed by a small amount of aircraft. This is because conventional aircraft are designed to lack this "instability" for safety reasons, and can thus not execute the maneuver by conventional means. Some conventional aircraft can however perform maneuvers reminiscent of the Cobra but does so with differences which disqualifies them as real Cobra maneuvers; such as: performing at low speed, changing alpha too slowly and using advanced thrust control so as not to gain altitude (i.e. performing a forced vertical climb with no thrust, usually ending with the aircraft performing a short climb or stalling instead of completing the cobra movement), among other examples.