United States Air Force Plant 42 (Plant 42) (IATA: PMD, ICAO: KPMD, FAA LID: PMD) is a United States Government aircraft manufacturing plant, used by the United States Air Force. It is also used by the National Aeronautics and Space Administration (NASA). Aerospace contractors at Air Force Plant 42 share a common runway complex and either lease building space from the Air Force (commonly referred to as GOCO, or Government Owned Contractor Operated), or own their own building outright. There are eight separate production sites specially suited for advanced technology and/or "black" program projects. Currently the most well–known contractors at Plant 42 are Boeing, Lockheed Martin (home of the legendary Skunk Works), and Northrop Grumman.