The A-10 Thunderbolt is unlike any “fighter” before or since, with survivability features designed to keep it flying during an attack run and make it back to base. The plane featured redundant engineering features designed to keep the plane flying though parts of it were shot away. The two General Electric TF-34 non-afterburning turbofans were moved behind the wing, in order to reduce the plane’s infrared signature and protect it from Soviet air defenses such as the SA-7 Grail shoulder-fired surface-to-air missile system. The A-10 pilot sits in a titanium “bathtub” protecting him or her from antiaircraft guns up to twenty-three millimeters—the primary armament of the ZSU-23-4 mobile air defense system. The flight-control systems and engines are also encased in titanium plate.