Well, the Air Force has figured out that its likely some combination of high operating altitudes and intense maneuvering at those altitudes that is causing either toxins to seep into the F-22 pilots' oxygen supplies or allowing insufficient amounts of oxygen to reach the pilots' lungs.
Lt. Gen. Janet Wolfenbarger, one of the service's top weapons buyers, just told Senators that it has narrowed down possible causes for Raptor pilots to be experiencing hypoxia like symptoms in-flight to those factors.
Now, it's almost a no-brainer that hypoxia-like symptoms are being triggered by either contaminants entering pilots' oxygen supplies or by the fact that said pilots aren't receiving enough oxygen since hypoxia happens when the brain isn't receiving enough oxygen. However, that it's the Raptor's crazy performance may be behind what's feeding its pilots limited or contaminated oxygen is pretty damned interesting; it hints that the jet is pushing the limits of aerospace science. Remember, the F-22 flies higher for longer than other jets and performs maneuvers that almost no other fighter in the world can match.
"We have some recent data that we are starting to believe, we are coming to closure on that root cause," said Wolfenbarger during a May 8 Senate Armed Services Committee hearing. "We're realizing that we operate this aircraft differently than we operate any of our other fighter aircraft, we fly at a higher altitude, we execute maneuvers that are high-G at that high altitude and we're on that oxygen system at those high altitudes for periods of time."
"I'm not ready to say yet that we're ready to declare a root cause," she added.
Keep in mind that the Air Force has been studying this problem for years and hasn't been able to find a cause -- despite enlisting the "best minds" from DoD, NASA, academia and industry to study the issue, as Wolfenbarger reminded the Senators today. The fact that the F-22 operates at such extreme (possibly record-setting) levels beyond what other fighters -- including the Navy's F/A-18E/F Super Hornet that uses a similar On-Board Oxygen Generating System (OBOGS) as the Raptor -- may explain why no one has been able to diagnose the problem.
Click here to read more about the woes with the Raptor's oxygen-system.