The F-22 Raptor is an American fighter aircraft that uses stealth technology. It is an air superiority fighter, but is equipped for ground attack, electronic warfare, and signals intelligence roles as well. The United States Air Force considers the F-22 a critical component of the US strike force.[6] Faced with a protracted development period, the aircraft was variously designated F-22 and F/A-22 during the three years before formally entering US Air Force service in December 2005, as the F-22A. Lockheed Martin Aeronautics is the prime contractor and is responsible for the majority of the airframe, weapon systems and final assembly of the F-22. Along with Lockheed Martin, partner Boeing Integrated Defense Systems provides the wings, aft fuselage, avionics integration, and all of the pilot and maintenance training systems. The F-22 is claimed by several sources to be the world's most effective air superiority fighter. The US Air Force claims that the F-22 cannot be matched by any known or projected fighter aircraft.[6] Air Marshal Angus Houston, chief of the Australian Defence Force, and former head of the Royal Australian Air Force, said in 2004 that the "F-22 will be the most outstanding fighter plane ever built." Type Stealth Air superiority fighter Manufacturers Lockheed Martin Aeronautics Boeing Integrated Defense Systems Maiden flight YF-22: 29 September 1990 F-22: 7 September 1997 Introduction 15 December 2005 Status Active: 91 Planned: 183 Primary user United States Air Force Number built 100 (as of September 2007) Program cost US$ 62 billion[4] Unit cost US$137.7 million as of 2007 Variants X-44 MANTA FB-22