The U.S. Air Force has grounded a quarter of its new F-35 stealth fighters after five pilots reported symptoms consistent with oxygen-deprivation.
The flight restriction, which affects 55 of the roughly 200 F-35s in service, has alarmed experts. They worry that, as the Air Force buys more and more F-35s, future groundings could affect a wide swath of the military’s fighter fleet.
But the Air Force is trying to put on a brave face on the problem. Service officials insist the Air Force will always have other options if its F-35s become unflyable.
Above 10,000 feet or so, the air thins out. A pilot flying above that altitude must breathe oxygen through a mask—or risk hypoxia. But if the mask or its attached filter malfunctions, the flier can still suffer hypoxia-like symptoms. Dizziness. Confusion. Even blackouts.
In recent years the U.S. military has struggled with hypoxia problems on many of its aircraft, including F-22 stealth fighters, T-45 training jets, and F/A-18 naval fighters.
The five F-35 pilots, all assigned to Luke Air Force Base in Arizona, reported hypoxia-like symptoms between May 2 and June 9. “In each case, the aircraft’s backup oxygen system operated as designed and the pilot followed the correct procedures, landing the aircraft safely,” Luke officials stated.
On June 9, Brig. Gen. Brook Leonard, commander of the 56th Fighter Wing at Luke, ordered his squadrons to stand down. “The Air Force takes these physiological incidents seriously, and our focus is on the safety and well-being of our pilots,” Leonard stated. “We are taking the necessary steps to find the root cause of these incidents.”
The grounding remained in effect as of Monday night. But none of the other four U.S. bases where F-35s operate have followed Luke’s lead—yet. “The safety of our pilots is a top priority, and we will continue to monitor operations, communicate with our airmen and the F-35 community, and will implement recommendations that may come as a result of the review into the incidents that were reported at Luke,” Erica Vega, a spokeswoman at the Air Force’s Virginia-based Air Combat Command, told The Daily Beast.
The Air Force said the problems at Luke are, for now, isolated to just that base. “It’s hyper-local right now,” Capt. Mark Graff, an Air Force spokesman at the Pentagon, told The Daily Beast. “The jets at Luke Air Force Base are a large portion of the F-35 fleet, but we still maintain combat readiness.... We still maintain operations as normal at four of five F-35 bases.”
But two experts The Daily Beast spoke to warned that hypoxia-related groundings could pose a strategic risk as the Pentagon pursues a decades-long plan to acquire as many as 2,300 F-35s— all in the hope that streamlining the fighter force will result in cost-savings. The military wants F-35s to eventually replace nearly every other fighter jet in its arsenal. U.S. allies are buying an additional 700 of the radar-evading warplanes.
In 2011, the Air Force sidelined all of its roughly 180 F-22s for four months following a spate of hypoxia incidents, possibly including a fatal crash. If, in the future, F-35 pilots suffer dizziness or confusion in flight and the military determines that the plane itself is to blame, it might have no other choice but to ground every F-35.
“When a situation like this arises that requires grounding the entire fleet—as happened when F-22 pilots experienced similar symptoms—that will take an enormous bite out of allied air power,” Dan Ward, a retired Air Force lieutenant colonel who has written two books about technology development, told The Daily Beast.
Ward said the best way to prevent a service-wide warplane-grounding is to operate lots of different kinds of planes that don’t all suffer the same technical problems at the same time. “That means fielding a fleet made of a blend of aircraft and not relying on the F-35 for 90 percent of our capacity,” Ward said
That blend could include F-35s and F-22s plus drones and even older fighters. Ironically, cost overruns and design problems— including a faulty electrical system and buggy software—have delayed and reduced F-35 production, forcing the Air Force to keep 30-year-old A-10s, F-15s and F-16s in service longer than it had planned.
“We’re going to continue to have a deliberate mix of aircraft all throughout our inventory,” Graff said. “No over-reliance on any single type of aircraft so we have a single point of failure.”
But today’s diverse fighter fleet isn’t actually “deliberate.” It’s an accident—a consequence of the F-35’s problems. If and when the Pentagon fixes the F-35 and finally buys enough of the planes to replace older models, it could expose itself to greater risk of widespread groundings, whether related to hypoxia or some other malfunction.
And to be clear, the Pentagon’s hypoxia problems aren’t likely to go away. “Hypoxia problems keep striking a variety of American aircraft,” Dan Grazier, a researcher at the Project on Government Oversight, told The Daily Beast. “You don’t have to be an aerospace engineer to understand that pilots need to have enough oxygen to breathe. Yet we still seem to have the same kind of problems.”