Air Force orders F-35s grounded at Arizona base

Pilots suffered oxygen deprivation during flights.

WASHINGTON — The U.S. Air Force has ordered a standdown of its F-35 Joint Strike Fighter aircraft at an Arizona base after pilots there said they suffered oxygen deprivation while flying the plane built by Lockheed Martin Corp.

Since May 2, five F-35A pilots assigned to Luke Air Force Base have reported physiological incidents while flying. According to a service press release, those pilots experienced hypoxia-like symptoms.

Hypoxia is a deficiency of oxygen reaching the body’s tissues. It’s a potentially life-threatening problem, and one that the U.S. Navy has also been wrestling with on its Boeing F-18 fighters.

So far, the Air Force’s F-35 problem has occurred only at Luke; other pilots flying the service’s newest fighter plane haven’t reported any incidents, according to the release.

“In order to synchronize operations and maintenance efforts toward safe flying operations we have canceled local F-35A flying,” said Brig. Gen. Brook Leonard, commander of the 56th Fighter Wing. “The Air Force takes these physiological incidents seriously, and our focus is on the safety and well-being of our pilots.

“We are taking the necessary steps to find the root cause of these incidents,” Leonard said.

This isn’t the first time a high-performance Air Force aircraft that flies at high altitudes has encountered such problems. In 2012, the Air Force had to track down a mystery after at least a dozen pilots flying Lockheed’s F-22 Raptor fighters became dizzy and disoriented. The service eventually determined a valve that regulated oxygen flow into the Raptor pilot’s pressure vest was too weak to prevent the vest from inflating unnecessarily and restricting the pilot’s ability to breathe.

During the F-35 grounding, wing officials will educate pilots on the situation, increase their awareness of hypoxia symptoms, and review training to deal with oxygen deprivation, according to the release.