Pilots are supposed to be tough physical specimens who can handle 9 Gs and still think fast. But flying at altitude — often in a pressurized flight suit — and breathing cleaned-up air from the engine intake sometimes leave pilots wondering what hit them. The number of such cases has been climbing rapidly in some aircraft recently, especially in the Boeing-built Navy and Marine Corps F-18 fighters and the Navy’s T-45 trainers. Combine that with the recent stand-down of Air Force F-35As at Luke Air Force Base after a rash of five possible hypoxia incidents, and you’ve either got a new systemic problem, a rash of pilots who are experiencing new symptoms or something new and unexpected.
Caret says Boeing is “really focused on a root cause” and is taking a rigorous systemic approach to study the issue. They’ve brought in medical personnel and others — whom she wouldn’t describe in detail except as experts — to advise the company. She really started getting involved in June last year.
Brig. Gen. Brook Leonard, pilot instructor at Luke and commander of the 56th Fighter Wing, told reporters Friday that commanders at Luke hope they’ll have a path to flight ready Monday afternoon, with the earliest return to flight possible by Tuesday afternoon. But he cautioned that was dependent on pilots demonstrating confidence in the plan for return. The Air Force remembers all too well when two F-22 Air National Guard pilots appeared on the TV show 60 Minutes to announce they were not willing to fly the Raptor because of suspected hypoxia incidents.
Leonard said there was a specific altitude at which the symptoms manifested themselves in the F-35A but he was not willing to say what it was to avoid tilting the investigation one way or another. To make sure the pilot community knows what’s happening and has confidence in how the Air Force is handling the issue, Leonard said they held a town hall meeting for pilots’ spouses.
He said one of the things the Air Force is considering is monitoring pilot’s blood oxygen levels in flight so they can combined that with the “exquisite data” already available about the plane’s performance. That might allow the service to make decisions with greater confidence.
Also, Leonard did not sound very impressed with the F-35’s On Board Oxygen Generation System (OBOGS), which skims air off the engine intake — an unlimited supply as long as the aircraft keeps flying — then purifies, cools and concentrates it for the pilots to breathe.
“We do think the OBOGS system is not as robust as it could be, but it does meet the minimum standard,” he said, without elaborating.
Meanwhile, at the Paris Air Show, Cobham will be unveiling a new testing system tomorrow for these so-called physiological events.
They’ve already delivered the first Inhalation Gas Sensor to the Air Force School of Aerospace Medicine, the company says in a release. It’s the first part of a two-stage system that will include an exhalation sensor block. They will capture environmental, oxygen system performance, and pilot physiological data “to help discern root cause of debilitating physiological events that continue to plague aircrew safety and mission readiness.”
“To unravel the mystery of root cause, we will start by creating a comprehensive mosaic of information that will simultaneously zero in on how the oxygen source equipment is performing, what the cockpit environmental conditions are around the pilot, and monitor the pilot’s physiological data captured in exhaled breath. This data will then be analyzed for correlations to physiological episodes and hypoxia-like symptoms that may have occurred during flight to ultimately help determine root cause,” Stuart Buckley, VP for business development and sales at Cobham Mission Systems, says in a statement. Perhaps this is the system Leonard mentioned, but I’m not sure.
The F-35 Joint Program Office is leading the investigation into the root causes of the suspected hypoxia incidents and is supporting the folks at Luke. The two F-35As slated to perform at the Paris Air Show have arrived safely.