The rate of F/A-18 Hornet pilots experiencing loss of oxygen mid-flight is holding steady, despite efforts to improve update systems, according to members of the House Armed Services Committee, who grilled top Navy officers on the issue at a hearing Thursday.
Pilots are experiencing so-called hypoxia events at a rate of 20 to 30 per 100,000 flight hours, a figure that hasn't changed in several years, said Rep. Niki Tsongas, D-Massachusetts., said, a figure that hasn't changed in several years.
"It is, I think, an issue that despite all your investments and policies and training and everything else … the numbers still don't go down," she said.
Hypoxia, a deficiency of oxygen reaching the tissues of the body, can prevent pilots from thinking clearly or reacting quickly while flying faster than the speed of sound. They may notice themselves gasping for air or getting light-headed, but its effects may also include lower mental acuity, delayed response time, a degradation of basic motor skills and loss of consciousness.
The Navy has kept a close eye on the problem since 2009, requiring reporting of all incidents to be reported as the service updates while updating cockpit filtration systems and developsing technology to monitor oxygen levels in -flight.
"The rates started to climb in 2010. That’s the year that we told everyone, okay 'OK, we think there’s a problem here, at Navy leadership,'" said Rear Adm. Mike Manazir, director of air warfare. "The phenomenon that you’re seeing between 2010 and now is an increase in reporting.
The Navy has fielded 18 or 19 changes to the aircraft so far, said Rear Adm. Michael Moran, director of the tactical aircraft program office. That includes , including new filtration systems in about 219 jets, with a goal of adding 40 more each month going forward.
For pilots and aircrew, hypoxia training has been ramped up to once a year rather than every four years, with dedicated simulation training for pilots every two years.
"What we do with the trainer now is, you get into a simulated cockpit on the ground, put an oxygen mask on and the system is set up so you can fly and they gradually reduce your oxygen content, and they train us to recognize the symptoms," Manazir said.
While in flight, the fix is a manual oxygen bottle that a pilot can use to regain enough stability to land the Hornet.
One of the main issues in tackling the problem is that the aircraft don't have a monitoring system to see what exactly is coming through the cockpit's filter, which cleans out nitrogen, carbon monoxide and other gases or toxins.
"It’s like chasing a ghost: You can’t figure it out, because the monitoring devices that do this are not on the airplane," Manazir said.
To work on that, researchers at Naval Air Systems Command in Patuxent River, Maryland, are testing whether there are unanticipated contaminants getting to pilots, and if a device could be added to their emergency gear to detect those contaminants them while still in the air.
That system is scheduled to go online in 2017, Moran said.
Still, Tsongas pressed for another solution.
"I appreciate Adm. Moran talking about the manual backup oxygen system, but I think we all would be concerned by the fact that you're asking a potentially incapacitated pilot to help himself out of this," she said.
The manual tank could have anywhere from minutes to an hour's worth of breathable air if used perfectly, she said, but the pilot could be hours away from the carrier at that point.
"As you're looking at creating a budget, an automatic system is something that would give much more time, and he or she would not have to activate it themselves," she said.
Manazir stressed that the Navy is confident in the F/A-18's systems and the pilots' ability to recognize and respond to hypoxia.
"A physiological event occurs when a pilot feels dizzy, feels confused, feels a little strange in the airplane," he said.
If there were concerns about the aircraft's safety, he added, the fleet would be grounded.