A number of military pilots have reported issues with oxygen systems in various aircraft in recent years, and now the U.S. Air Force has grounded its F-35 Joint Strike Fighter fleet at Luke Air Force Base in Arizona, after five incidents in which pilots complained of hypoxia-related issues. The problems occurred between May 2 and June 8. Backup oxygen systems took over, and the pilots all landed safely. Training flights at the base were canceled on Friday and were scheduled to resume on Monday, but now the grounding has been extended indefinitely. About 55 F-35s are based at Luke, and a total of 220 are flying in the U.S. and allied nations.
The Navy grounded its fleet of T-45 trainer jets in April, after pilots refused to fly, citing faulty oxygen systems that had caused blackouts in the cockpit. A Navy official said this week they still haven’t identified the problem. “We’re not doing well on the diagnosis,” Vice Adm. Paul Grosklags, commander of Naval Air Systems, told lawmakers on Tuesday. “To date, we have been unable to find any smoking gun.” The Navy has “literally torn the T-45s apart” looking for the source of the problem, according to the Marine Times. The lack of flights has delayed 25 students per month from graduating. Grosklags said the Navy will continue testing the aircraft, and will consider resuming student flights in “a matter of weeks instead of months,” the Marine Times reported.