The Sukhoi Su-57 (; NATO reporting name: Felon) is a stealth, single-seat, twin-engine multirole fifth-generation jet fighter being developed since 2002 for air superiority and attack operations. The aircraft is the product of the PAK FA (, ), a fifth-generation fighter programme of the Russian Air Force. Sukhoi's internal name for the aircraft is T-50. The Su-57 is the first aircraft in Russian military service to use stealth technology. Its maiden flight took place on 29 January 2010 and it entered service on 25 December 2020. It is the world's fourth operational fifth-generation stealth fighter aircraft after the F-22, F-35, and J-20.