More Troubles: US Air Force Grounds 55 F-35s as Pilots Suffer Oxygen Deprivation

A total of 55 F-35 Lightning II Joint Strike Fighters were grounded after five incidents in which pilots experienced symptoms of oxygen deprivation.

WASHINGTON (Sputnik) — The US Air Force has been forced to halt flights of 55 F-35 Lightning II Joint Strike Fighters after five pilots suffered oxygen deprivation in problems with their air supply systems, according to US media reports.

"The US Air Force has grounded 55 of its F-35 Joint Strike Fighters at Arizona’s Luke Air Force base following five incidents in which pilots experienced symptoms of oxygen deprivation," Defense One reported on Friday.

US Air Force F-35s had previously been grounded in September 2016 as fight operations had to be suspended after a discovery that electrical lines in their fuel tanks had cracked, the report noted.

The pilots "reported physiological incidents while flying," but a reserve oxygen system was activated so they could return to base safely, US Air Force spokesman Captain Mark Graff told Defense One in an email.

Graff also stated in the email that the aircraft should be back in the air on Monday.

The F-35 program is scheduled to cost more than $1 trillion making it the most expensive aircraft and weapons program in history and the plane has been repeatedly dogged by systems breakdowns and failures.