The PAK FA (an acronym for Perspektivny Aviatsionny Kompleks Frontovoy Aviatsii, or Prospective Aeronautical Complex of Frontline Air Force) was the Russian military program launched in the early 2000s to develop a fifth-generation stealth fighter. Designed to replace the aging Su-27 “Flanker” and MiG-29 “Fulcrum” fleets, the PAK FA was intended to be Russia’s technological peer to the American F-22 Raptor. The project, led by the Sukhoi Design Bureau under the internal designation T-50, focused on combining low-observable (stealth) technology with supermaneuverability, supercruise, and advanced sensor fusion. The program successfully culminated in the Sukhoi Su-57 (NATO reporting name “Felon”), which became the first aircraft in the Russian inventory to utilize stealth as a core design principle, effectively superseding earlier experimental concepts like the MiG 1.44.