Fifth-generation jet fighter

A fifth-generation jet fighter is a jet fighter classification used around the world that encompasses the fighter technologies developed during the first part of the 21st century. As of 2019[update] these are the most advanced aircraft. The exact characteristics of fifth-generation jet fighters are controversial and vague, with Lockheed Martin defining them as having all-aspect stealth even when armed, low-probability-of-intercept radar (LPIR), high-performance airframes, advanced avionics features, and highly integrated computer systems capable of networking with other elements within the battlespace for situation awareness. As of December 2018[update], the only combat-ready fifth-generation fighters are the Lockheed Martin F-22 Raptor, which entered service with the United States Air Force in 2005; the Lockheed Martin F-35 Lightning II, which entered service in 2015; and the Chengdu J-20, which entered service with the People's Liberation Army Air Force (PLAAF) in September 2017. The Shenyang J-31 had flight testing of the 3.0 revised version in 2017. The Mitsubishi X-2 Shinshin, TAI TFX, and HAL AMCA are in the early stages of development. The Sukhoi Su-57 is slated for delivery to the Russian Air Force in 2019.