Editing Lockheed Martin F-22 Raptor (section)

===Initial operational problems===
During the initial years of service, F-22 pilots experienced symptoms as a result of oxygen system issues that include loss of consciousness, memory loss, [[emotional lability]] and neurological changes as well as lingering respiratory problems and a chronic cough; the issues resulted in a fatal mishap in 2010 and four-month grounding in 2011 and subsequent altitude and distance flight restrictions.<ref name="Cox">Cox, Bob. "Despite investigation, safety concerns linger on F-22." ''Star Telegram'', 25 August 2012.</ref><ref name=CBS_60min>Sughrue, Karen (producer) and [[Lesley Stahl]]. [https://www.cbsnews.com/news/is-the-air-forces-f-22-fighter-jet-making-pilots-sick/ "Is the Air Force's F-22 fighter jet making pilots sick?"] ''[[60 Minutes]]: CBS News'', 6 May 2012. Retrieved 7 May 2012.</ref> In August 2012, the DoD found that the BRAG valve, which inflated the pilot's vest during high-''g'' maneuvers, was defective and restricted breathing and the OBOGS (onboard oxygen generation system) unexpectedly fluctuated oxygen levels at high ''g''.<ref>{{Citation |url= http://www.military.com/daily-news/2012/08/01/air-force-confident-f22-oxygen-riddle-solved.html |newspaper= Military |title= Air Force Confident F-22 Oxygen Riddle Solved |first= Michael |last= Hoffman |date= 1 August 2012 |access-date= 28 April 2019 |archive-url= https://web.archive.org/web/20190330170855/https://www.military.com/daily-news/2012/08/01/air-force-confident-f22-oxygen-riddle-solved.html |archive-date= 30 March 2019 |url-status=live |df= dmy-all}}</ref><ref>Fabey, Michael. [http://www.aviationweek.com/Article.aspx?id=/article-xml/asd_10_12_2012_p03-02-506094.xml "USAF Still Reviewing Oxygen Concentration Levels For F-22 Cockpit."] {{webarchive|url=https://web.archive.org/web/20130419120544/http://www.aviationweek.com/Article.aspx?id=%2Farticle-xml%2Fasd_10_12_2012_p03-02-506094.xml |date=19 April 2013}} ''Aerospace Daily & Defense Report'', 12 October 2012.</ref> A Raptor Aeromedical Working Group had recommended changes in 2005 regarding oxygen supply that were unfunded but received further consideration in 2012.<ref>Talmadge, Eric. [https://web.archive.org/web/20121001003217/http://finance.yahoo.com/news/ap-impact-air-force-insiders-foresaw-f-22-084352828.html "AP Impact: Air Force insiders foresaw F-22 woes."] Associated Press, 27 September 2012.</ref><ref>{{cite magazine |last=Axe |first=David |url=https://www.wired.com/dangerroom/2012/09/f-22-oxygen-unsolved/ |title=Stealth Fighter's Oxygen Woes Still A Mystery, Air Force Admits |magazine=Wired |date=13 September 2012 |access-date=1 November 2013 |archive-url=https://web.archive.org/web/20131203153739/http://www.wired.com/dangerroom/2012/09/f-22-oxygen-unsolved/ |archive-date=3 December 2013 |url-status=live}}</ref> The F-22 CTF and 412th Aerospace Medicine Squadron eventually determined breathing restrictions as the root cause; coughing symptoms were attributed to acceleration [[atelectasis]]{{refn|Atelectasis is the collapse or closure of a lung resulting in reduced or absent gas exchange.|group=N}} from high ''g'' exposure and OBOGS delivering [[Oxygen toxicity|excessive oxygen concentration]]. The presence of toxins and particles in some ground crew was deemed unrelated.<ref name=physio>[http://www.gpo.gov/fdsys/pkg/CHRG-112hhrg76215/html/CHRG-112hhrg76215.htm "H.A.S.C. No. 112-154, F-22 pilot physiological issues."] {{Webarchive|url=https://web.archive.org/web/20180925121602/https://www.gpo.gov/fdsys/pkg/CHRG-112hhrg76215/html/CHRG-112hhrg76215.htm |date=25 September 2018}} '' GPO''. Retrieved 16 August 2013.</ref> Modifications to the life support and oxygen systems, including the installation of an automatic backup, allowed altitude and distance restrictions to be lifted in April 2013.<ref>{{cite web|last=Mowry |first=Laura |url=https://www.edwards.af.mil/News/story/id/123344796/ |title=Edwards Airmen vital to Raptor's return |publisher=U.S. Air Force |date=17 April 2013 |access-date=18 April 2013 |url-status=live |archive-url=https://web.archive.org/web/20130603082323/http://www.edwards.af.mil/news/story.asp?id=123344796 |archive-date=3 June 2013}}</ref>