The Lockheed Martin F-22 Raptor is a single-seat, twin-engine, all weather stealth tactical fighter aircraft developed for the United States Air Force (USAF). The result of the USAF's Advanced Tactical Fighter program, the aircraft was designed primarily as an air superiority fighter, but has additional capabilities including ground attack, electronic warfare, and signals intelligence roles. Lockheed Martin is the prime contractor and is responsible for the majority of the airframe, weapon systems, and final assembly of the F-22, while program partner Boeing provides the wings, aft fuselage, avionics integration, and training systems. The aircraft was variously designated F-22 and F/A-22 prior to formally entering service in December 2005 as the F-22A. Despite a protracted development as well as operational issues, the USAF considers the F-22 a critical component of its tactical air power, and states that the aircraft is unmatched by any known or projected fighter. The Raptor's combination of stealth, aerodynamic performance, and situational awareness gives the aircraft unprecedented air-to-air capabilities. Air Chief Marshal Angus Houston, former Chief of the Australian Defence Force, said in 2004 that the "F-22 will be the most outstanding fighter plane ever built."
Since entering service, operational problems have been experienced and some have caused fleet-wide groundings. Critically, F-22 pilots have experienced symptoms that include loss of consciousness, memory loss, emotional lability and neurological changes. Pilots have also experienced lingering respiratory problems and a chronic cough. A number of possible causes were investigated, including possible exposure to noxious chemical agents from the respiratory tubing, pressure suit malfunction, side effects from oxygen delivery at greater-than-atmospheric concentrations, and oxygen supply disruptions. The fleet was grounded for four months in 2011 before resuming flight, but reports of oxygen issues persisted.[185] The problems resulted in inflight brain monitoring being considered by the USAF. In 2005, the Raptor Aeromedical Working Group, a USAF expert panel, recommended several changes to deal with the oxygen supply issues, though they were initially not funded on cost grounds; the recommended changes received further consideration in 2012.[187][188] In August 2012, the Pentagon found that the breathing regulator/anti-g (BRAG) valve, used to inflate the pilot's vest during high G maneuvers, was defective, inflating the vest at unintended intervals and restricting the pilot's breathing.[189] The on-board oxygen generating system (OBOGS) also unexpectedly reduced oxygen levels during high-G maneuvers. Consequently, new backup oxygen generators were installed and the carbon filters were changed to reduce lung exposure to carbon particulates. The coughing symptoms have been attributed to acceleration atelectasis ("collapse or closure of a lung resulting in reduced or absent gas exchange") due to high g exposure and the F-22 delivering higher concentrations of oxygen compared to prior aircraft. The presence of toxins and particles in some ground crew was deemed to be unrelated.[192] After the F-22 Combined Test Force and 412th Aerospace Medicine Squadron determined that breathing restrictions on the pilot were the root cause, the resulting modifications to the life-support equipment and oxygen system allowed the distance and altitude flight restrictions to be lifted on 4 April 2013.
On 22 September 2014, F-22s performed the type's first combat sorties by conducting some of the opening strikes of Operation Inherent Resolve, the American-led intervention in Syria; aircraft dropped 1,000-pound GPS-guided bombs on Islamic State targets near Tishrin Dam. Between September 2014 and July 2015, F-22s flew 204 sorties over Syria, dropping 270 bombs at some 60 locations. Throughout their deployment, F-22s conducted close air support (CAS) and also deterred Syrian, Iranian, and Russian aircraft from attacking U.S.-backed Kurdish forces and disrupting U.S. operations in the region. F-22s also participated in the U.S. strikes on pro-government forces in eastern Syria on 7 February 2018. These strikes notwithstanding, the F-22's main role in the operation was gathering intelligence, surveillance and reconnaissance. An F-22 refueling prior to combat operations in Syria, September 2014 In late 2014, the USAF was testing a rapid deployment concept involving four F-22s and one C-17 for support, first proposed in 2008 by two F-22 pilots. The goal was for the type to be able to set up and engage in combat within 24 hours.[179][180] Four F-22s were deployed to Spangdahlem Air Base in Germany in August and Lask Air Base in Poland and Amari Air Base in Estonia in September 2015 to train with NATO allies. In November 2017, F-22s operating alongside B-52s bombed opium production and storage facilities in Taliban-controlled regions of Afghanistan.[182] In 2019, the F-22 cost US$35,000 per flight hour to operate.
