In all the discussions of the relative merits of the F-22 Raptor vs. the F-35 Lightning II, one of the assumptions is that the F-22 actually works the way it’s supposed.

It appears that it doesn’t, and it’s bad enough that pilots are refusing to fly it:

While I was unable to attend this (30 April) morning’s briefing at Joint Base Langley-Eustis down in Hampton, Virginia, press reports from the event indicate that the US Air Force is admitting that a “small number” of Lockheed Martin F-22 Raptor pilots are refusing to fly the jet.

“Obviously it’s a very sensitive thing because we are trying to ensure that the community fully understands all that we’re doing to try to get to a solution,” says Air Combat Command chief Gen Mike Hostage as quoted by the Associated Press.

The USAF has not found the root cause of 11 hypoxia-like cases since the Raptor fleet returned to flight in September after a near five-month stand-down. The F-22 fleet has flown about 12,000 times since then.

What’s more, there is currently no clear indication as to what is causing the problem: (paid subscription required)

The U.S. Air Force is narrowing its focus on new combinations of factors as it explores hypoxia events that claimed the life of one F-22 pilot and plagued the fleet for more than a year.

Service officials remain frustrated, that a “smoking gun” for the cause is still elusive despite an extraordinary effort to enlist scientists, the medical profession and fighter experts in a quest for answers.

The Lockheed Martin F-22 is the Air Force’s premier, twin-engine, stealthy fighter. It cost more than $200 million per copy to produce, including R&D. It entered service in 2005, and the 188th and final unit was delivered on May 2.

The problem came to light after a November 2010 crash that claimed the life of a pilot. The fleet was grounded for four months last year as officials scrambled to find a cause; flights resumed in September. Since then, Air Combat Command (ACC) officials say there have been 11 hypoxic events. The unknown nature of the incidents has rattled the service. “There is no startling similarity [in the incidents] other than . . . hypoxic-like indications,” says Gen. Mike Hostage, ACC commander.

………

Additionally, pilots are wearing a pulse oximeter to monitor oxygen-saturation levels during flight ; if it dips below 85%, they are required to return to base immediately (the data are downloaded after landing and not dispatched in real time).

Lyon acknowledges an impact on the training hours that pilots can achieve. Hostage adds that the incidents have prompted some pilots to decline flying the Raptor , though he says these incidents are the exception. He notes that any guidance, such as returning to base with a low oxygen-saturation level, can be waived in the event of an operational requirement for F-22 use.

In the meantime, the Air Force acknowledged first to Aviation Week that F-22s have been deployed to the Middle East. The aircraft are operating out of Al Dhafra Air Base in the United Arab Emirates.

So, they don’t know what is causing this, they have to require pilots to wear a blood oxygen sensor, and they are (finally) deploying some of them overseas.

My guess would be that they won’t be deploying to the 65,000 foot ceiling.