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Flight restrictions lifted for F-22 fighters equipped with new automatic oxygen backup system

The United States Air Force’s F-22 Raptor air superiority fighters have been the subject of flight restrictions since May of 2012. These flight restrictions were part of a response to hypoxia-like symptoms some pilots experienced during flights.

The United States Air Force had expected a fix for the onboard oxygen generator, which is suspected to be part of the problem causing the hypoxia-like symptoms in some pilots, by the end of 2012. This led to flight restrictions being placed on F-22 fighters that limited them to operation within 30 miles of a safe landing area.

The United States Air Force Air Combat Command announced this week that those restrictions mandated by former Defense Secretary Leon Panetta in May of 2012 have finally been lifted. The affected F-22s have been retrofitted with an automatic backup oxygen system instead of the previous manual system. The Air Force expects the new oxygen system to be installed on all F-22 fighters by July 2014.
fatal F-22 crash in Alaska in November 2010 occurred after the pilot was unable to activate the manual backup oxygen system. In that fatal accident the Air Force ruled that while the onboard oxygen generation system in the Raptor had failed, pilot error was the ultimate cause of the crash because of the pilot's inability to activate the backup oxygen system.

Last July, investigators announced that the primary cause of these hypoxia symptoms was a leaky valve in the Combat Edge life-support vest. The investigators said that the leaking valve caused the vest to inflate unnecessarily at lower altitudes, restricting the pilot's ability to breathe. Those problematic valves were replaced in January.

Source: Defense News

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RE: Balderdash.
By Solandri on 4/6/2013 4:06:13 PM , Rating: 3

If you read the sequence of events, I don't see where the pilot erred. He was at 50,000 feet when the oxygen generator and pressurization cut out. At that altitude, no oxygen and no pressure = unconscious in 10-15 seconds. There's so little natural oxygen at that pressure that it's essentially the same as being exposed to a hard vacuum. (And to address a comment in that old article, no you can't hold your breath. First you couldn't react fast enough before the air was already gone out of your lungs. And second even if you just happened to be holding your breath just prior to depressurization, the approx 13 psi pressure difference would cause your chest to explode.)

In those 10-15 seconds, the pilot did the correct thing - pointed the plane down so he could get into thicker air which had sufficient oxygen to keep him alive. Unfortunately it seems he fell unconscious soon thereafter (little to no input on the controls for 39 seconds). This was followed by a hard 7.5g maneuver shortly before impacting the ground, which would be consistent with him waking up just before impact and trying to pull the plane out of the dive. He probably should've ejected, but you're pretty groggy when you wake up from oxygen deprivation. So his trained automatic functions (fly the plane) probably kicked in before his cognitive functions (decide whether or not to sacrifice the plane and eject) woke up sufficiently to make that decision.

The USAF blamed the accident on the pilot on the basis of those 39 seconds of little to no control inputs. But he was most likely unconscious during that time due the oxygen generator and pressurization system failure.

RE: Balderdash.
By Reclaimer77 on 4/6/2013 7:27:50 PM , Rating: 1
He had 15-20 seconds to activate the backup system. In fighter plane time, that's an eternity. The pilot clearly did not properly identify his symptoms, and thus he died due to incompetence.

Flying a fighter plane isn't like riding a bike down the street. Things can go wrong, and go wrong FAST. And it's up to your skill, and your ample training to make the right call.

In those 10-15 seconds, the pilot did the correct thing - pointed the plane down so he could get into thicker air which had sufficient oxygen to keep him alive.

Uh no, that was absolutely the WRONG thing to do. He didn't have time for that, not nearly enough time. He made the wrong call. He should have activated his backup oxygen first. In fact I can guarantee you this was drilled into his head as the first step before attempting a descent.

Instead of cooking up conspiracy theories about the Air Force "covering up" stuff, we need to understand they have far different expectations of their pilots than civilians do of their planes. That's the harsh reality of military life. If the checklist says to activate a backup system, and you don't, it's on YOU. Plain and simple.

If he had enough air and time to put the plane in a dive, he damn sure had enough time to flick a switch. One that would have saved his life. I'm not trying to sound harsh, I realize a man died, but that's the way it goes in his occupation.

RE: Balderdash.
By blazeoptimus on 4/6/2013 10:49:54 PM , Rating: 2
You make a good argument, and nobody's screaming conspiracy. Most of the people here have cried 'foul', and for good reason. As you said, the pilot missed a step on his checklist, plain and simple. The military ruled 'pilot error' - cased closed,,,,,,except - they did everything but ground one of there most prized aircraft so that no pilot could ever 'error' in the same way again. That means that at some level the Air Force realized the requirements on the pilots were to great, ergo the pilot is not to blame. I realize that these pilots are held to a high standard for there hundreds of millions dollars aircraft, but its also important to remember that this isn't an Apollo crew that has every possible failure contingency hammered into there heads.

RE: Balderdash.
By Manch on 4/8/2013 8:24:44 AM , Rating: 2
All of the Apollo crews were required to be military trained pilots. EPs are hammered into the heads of mil pilots. I'd argue that training for todays pilots are far more intense than it was for the Apollo crews

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