The US Air Force (USAF) has temporarily grounded the new F-35A Lightning II joint strike fighter at Luke Air Force Base (AFB), Arizona, after pilots complained hypoxia-like symptoms.
Hypoxia is a condition in which the body suffers a deficiency in the amount of oxygen reaching the tissues.
On 9 June, the USAF’s 56th Fighter Wing suspended local flying operations for F-35A fighter jets after five hypoxia incidents were reported.
The aircraft’s backup oxygen system functioned as designed and the pilots were able to safely land the aircraft.
56th Fighter Wing commander brigadier general Brook Leonard said: "In order to synchronise operations and maintenance efforts toward safe flying operations, we have cancelled local F-35A flying.
“The airforce 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."
The cancellation of local flying operations is currently limited to Luke AFB.
Officials at 56th Fighter Wing have increased the US and international pilots’ awareness of hypoxia symptoms.
Pilots will also be briefed on physiological symptoms and the extensive measures that are being taken to analyse data collected from hypoxia incidents.
To better understand the issue, the F-35 Joint Program Office has formed an action team of engineers, maintainers and aeromedical specialists.
The F-35 Lightning II is capable of providing the pilot with situational awareness, positive target identification, and precision strike in all weather conditions.
This multirole fighter has been designed to replace ageing fighter inventories, including USAF F-16s and A-10s, US Navy F/A-18s, US Marine Corps AV-8B Harriers and F/A-18s, as well as UK Harrier GR 7s and Sea Harriers.