The 56th Fighter Wing at Luke Air Force Base, Arizona has canceled local flying operations for F-35A Lightning II aircraft after pilots reported suffering symptoms similar to hypoxia, or oxygen deprivation.

There have been five incidents since May 2, but Air Force officials tell Fox News the aircraft have not been “grounded.”

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

The cancellation of flying is limited to F-35s at Luke Air Force Base.

All of the pilots were able to land their aircraft safely by using the aircraft's backup oxygen system.

Pilots will also be briefed on all the incidents that have occurred and the successful actions taken by the pilots to safely recover their aircraft.

The F-35 Joint Program Office has put brought together an “action team” of engineers, maintainers and aeromedical specialists to examine the incidents.

Fox News' Jennifer Griffin contributed to this report