Anyone who has studied air accidents knows that seemingly minor problems can cause catastrophes. Air France suffered the worst crash in its history three years ago when malfunctioning air-speed indicators on a Paris-bound Airbus A330 flying over the South Atlantic set in motion a series of cockpit errors leading to engine stall and the loss of 228 lives. After looking at evidence from the crash investigation, Airbus recommended that A330 air-speed gauges be replaced with a more reliable design from a different maker.
The Air Force seems to be following a different path in addressing sporadic instances of hypoxia — oxygen deprivation — among pilots flying its top-of-the-line F-22 Raptor fighter. In a plane with the performance features of the Raptor, even mild cases of hypoxia can have fatal consequences, so the Air Force has spent a lot of time and money trying to figure out what’s causing the problem. Last month, the director of operations at the service’s Air Combat Command, Major General Charles Lyon, said he was confident that the cause had been found: a faulty “breathing regulator / anti-gravity” (BRAG) valve in pressure vests worn by Raptor pilots. The vests inflate to help pilots resist G-forces as the fighter maneuvers at high speed, but if they inflate too soon they can restrict breathing.
Maybe Gen. Lyon is right, however even he described what Air Force investigators had found as a “mosaic” of evidence rather than a smoking gun. It’s a little troubling that premature inflation of the pressure vests, the factor supposedly leading to the hypoxia, hadn’t been noticed by pilots wearing the vests. It’s also hard to understand why only a handful of pilots wearing the vests suffered oxygen deprivation. And Gen. Lyon’s warning that cases of hypoxia would still crop up even after fixes are implemented isn’t exactly reassuring. Because Raptors weren’t bought in sufficient numbers to meet wartime needs, the Air Force can’t afford to lose them or their highly skilled pilots in training missions.
So what should the Air Force do if the valves are replaced or the vests are removed and an unacceptable pattern of hypoxia cases persists? At that point, the service would have to take another hard look at the on-board oxygen generation system, which was where it once thought the problem was originating. It is already planning some adjustments to that system as part of a package of fixes aimed at minimizing pilot danger. But a better fix might be to replace the system. Is it just a coincidence that the pilots of F-15 and F-16 fighters flying out of the same bases where F-22 hypoxia cases have occurred — and executing similarly demanding maneuvers — have not suffered the same symptoms?
It could be because they stopped wearing the pressure vests years ago, as Brian Everstine reported in Air Force Times. But it could also be because their fighters are equipped with a different make of on-board oxygen generator. The maker of their generators, Cobham, has an 85% market share, and one reason why is that problems are seldom traced to its equipment. Hopefully, the solution the Air Force is now pursuing will fix the problem and restore Raptor to a high state of readiness. But if it doesn’t, the time will have come to consider installing a new oxygen system. Airbus looked at the A330 crash and decided that just because a problem was exceedingly rare didn’t mean it was an acceptable risk.
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