The Grumman A-6 Intruder is an American twinjet all-weather attack aircraft developed and manufactured by American aircraft company Grumman Aerospace that was operated by the U.S. Navy. It was designed in response to a 1957 requirement issued by the Bureau of Aeronautics for an all-weather attack aircraft for Navy long-range interdiction missions and with STOL capability for Marine close air support. It was to replace the piston-engined Douglas A-1 Skyraider. The requirement allowed one or two engines, either turbojet or turboprop. The winning proposal from Grumman used two Pratt & Whitney J52 turbojet engines. The Intruder was the first Navy aircraft with an integrated airframe and weapons system. Operated by a crew of two in a side-by-side seating configuration, the workload was divided between the pilot and weapons officer (bombardier/navigator (BN)).