later in the year, and was redesignated Su-37. Operational history During the subsequent flight-test programme, the Su-37's supermaneuverability as a result of thrust-vectoring controls became apparent. According to Simonov, such a feature would allow pilots to develop new combat manoeuvres and tactics, greatly enhancing its effectiveness in dogfights. Among the new manoeuvres was the Super Cobra, which was a variation of the Pugachev's Cobra and was demonstrated during the aircraft's international debut at the Farnborough Airshow in September 1996. Piloted by Frolov, the aircraft pitched up 180 degrees and maintained the tail-first position momentarily, which would theoretically allow the aircraft to fire a missile at a combat opponent. The Super Cobra evolved into the kulbit (somersault), in which the Su-37 performed a 360-degree loop with an extremely tight turning radius the length of the aircraft. According to test pilot Anatoly Kvochur, thrust vectoring would have given the aircraft a considerable advantage in close-in dogfights. Nonetheless, critics have questioned the practical benefits of such manoeuvres; although they would allow an early missile lock-on, it would come at the expense of a rapid loss of kinetic energy, which would leave the aircraft vulnerable when pilots missed their first shot. The aircraft was demonstrated at the Paris Air Show in 1997. Although it was only able to perform on the last day of the show, the organisers recognised the Su-37 as the standout performer at the event. The aircraft thereafter participated in the MAKS air show in Moscow, the International Defence Exhibition in Dubai, and the FIDAE air show in Santiago, Chile, as authorities sought to export the aircraft. With the expiration of the engines' service lives, the aircraft later had the AL-37FUs replaced with standard production AL-31F engines that lacked movable nozzles. The loss of thrust vectoring was somewhat compensated for by an update to the fly-by-wire flight control system. The aircraft's foreign avionics were also replaced with indigenous designs. It resumed test flights in October 2000. The flight-test programme was ended on 19 December 2002, when the aircraft's port horizontal tail broke off during a high-g manoeuvre, leading to its crash at Shatura, near Moscow. The structural failure was caused by repeated exceeding of the aircraft's design load during six years of testing. The pilot Yuri Vashuk ejected safely. Despite the entry of the Su-37 into Brazilian and South Korean fighter tenders, the aircraft failed to gain any foreign customers. India