Planes’ oxygen woes ID’d, Air Force says
General won’t say what researchers found or their fixes
The Air Force’s top commander says a team of researchers has cracked the mystery of why dozens of pilots, some of them in San Antonio, have suffered midair blackouts or other physiological episodes this year while flying the T-6A Texan II, the service’s primary trainer.
Gen. David Goldfein, the service’s chief of staff, said he has “high confidence” that the Air Force, Navy and NASA have figured out why the plane’s onboard oxygen generation system — called OBOGS — has repeatedly malfunctioned. But he declined to say what the problem is or how the Air Force would fix it.
“I’m confident that the team has come to an answer,” Goldfein said in a lengthy interview. “I do want to dig into the engineering piece of it because as the chief I owe it to the force to make sure that I understand the next level of detail of this. But what I’ve been briefed to date, my confidence is very high that we’ve isolated it and determined the root cause, and we’re going to have good fixes in place. And I wish I could tell you what it was. I’ve just got to let our process play out.”
The OBOGS failures, which have resulted in at least 61 reported unexplained physiological episodes during the first six months of this year, prompted the Air Force’s training command to ground the T-6A in February. It re-
turned the plane to service in March, announcing a more frequent cleaning, testing and maintenance schedule for the oxygen system while it continued an intensive search for a root cause.
The San Antonio Express-News recently learned that pilots were told that the cause has been found but not what it was or how the problem would be solved.
Goldfein said pilots will be briefed within the next two weeks, both on the cause and the next steps.
Developed in the early 1980s, OBOGS draws outside air from a plane’s engine. The air is cooled and passes through a device called a molecular sieve concentrator, which uses a chemical process to produce oxygen. A Congressional Research Service brief said OBOGS delivers 95 percent oxygen and 5 percent argon to pilots. The Navy says the mix is cleaner than that in a typical office.
‘Holistic approach’
The grounding of the T-6A came after 22 unexplained physiological episodes, or UPEs, as the Air Force calls them, were recorded in January, the most ever seen in the single-engine, two-seat turboprop since it was introduced in 2000.
In clearing the way for the plane to fly, the Air Education and Training Command said it was safe after flawed OBOGS components were replaced. Goldfein echoed that view, saying, “Even though we found those parts were failing at a higher rate, not one of them nor all of them together could actually explain everything that was going on, so we didn’t stop.”
But T-6A pilots suffered 39 UPEs from March through June, and some pilots have complained that months of investigation by the Air Force hadn’t produced a fix.
The Navy, meanwhile, has not completed its root-cause analysis for similar problems with its primary trainer, the T-45 Goshawk. That investigation has lasted nearly two years, but technicians have added an oxygen monitoring device and plan to install a new oxygen concentrator, said Cmdr. Scot Cregan, a spokesman for the Navy’s Physiological Episodes Action Team in Arlington, Va.
Goldfein said the Air Force, Navy and NASA have adopted a “holistic approach” to studying the OBOGS on the T-6A, something his service did years ago when similar problems emerged with the F-22A Raptor.
That, Goldfein said, “is what allowed us to get to a point where, with high confidence, I can say, all right, we understand what is going on, we have fixes in place where we can communicate this to the pilots” and their families.
“Given the number of months it’s taken, I understand completely that they’re going to be a little bit skeptical at first,” he said. “I don’t blame them. … They’re strapping on these airplanes to do the nation’s business, and we owe it to them to make sure that they are confident and we’re confident that they’re safe to fly.”
Different onboard oxygen delivery systems are used in a variety of military aircraft, including fighters and the T-45.
Hypoxia, a lack of oxygen that is potentially fatal, with symptoms ranging from fear, anxiety and giddiness to complacency and loss of consciousness, was suspected when an instructor pilot and student bailed out of a T-45 from Naval Air Station Kingsville that crashed Aug. 14, 2016.
Problems with the Goshawk’s OBOGS prompted the Navy to ground it more than a year ago before allowing the carrier-capable jet to fly under restrictions until changes were made to the oxygen system. The Goshawk has had 11 physiological episodes over the past 14 months, none of them hindering the ability of aviators to land safely, the Navy said.
Maintenance issues
The T-6A had enjoyed one of the lowest occurrences of unexplained physiological episodes over the past 10 years. The Air Force spike of 22 in January was far higher than anything seen before.
Goldfein said the Air Force wondered why the T-6A episodes over time exceeded those recorded by the Navy, which also flies the T-6A and T-6B, a newer model of the Texan II. The Air Force systems were older, and the Navy maintains its differently, he said, adding, “It’s really healthy to take a look at how everybody else is doing business.”
Maintenance issues came on Goldfein’s radar earlier this year. He ordered a one-day safety stand-down May 7 in the wake of a WC-130 Hercules crash five days earlier that killed nine members of the Puerto Rican Air National Guard. There have been eight manned aircraft crashes this year, resulting in 19 fatalities, making 2018 the worst since 2002, when 22 people died.
Goldfein said a recently submitted Air Force safety center report compiled from active-duty, guard and reserve wing commanders showed less experience in aircraft operations and maintenance stemming from personnel shortages now being reduced “to zero.”
“So it’s actually not surprising to me that one of the feedback I got was, hey, we got more maintainers, but they’re a lot younger, and that contributes to safety risk,” he said.
He was in San Antonio to address the Air Force Sergeants Association’s Professional Airmen’s Conference on Thursday.
Unlike the Navy, the Air Force has not provided a breakdown of physiological episodes by base or listed their severity, but veteran instructor pilots have told the Express-News of an incident in which a Joint Base San AntonioRandolph aviator suffered a physiological episode early this year that was so serious that a number of pilots there refused to fly.
Their chief concern was hypoxia, but other possible causes of UPEs involve hypocapnia, a state of reduced carbon dioxide in the blood, and hypercapnia, excessive carbon dioxide in the blood, usually caused by inadequate respiration.
‘We did not stop’
Pilots who spoke on condition of anonymity said that up to 11 aviators at Randolph’s 12th Flying Training Wing had refused to fly early this summer because of concerns about the OBOGS. Lt. Col. J.C. Gorman, who had taken command of the 559th Flying Training Squadron days earlier, canceled all his T-6A missions June 25 after meeting that morning with recalcitrant pilots. He said some who had ruled out flying changed their minds after talking it over.
The squadron returned to a regular schedule the next day.
Goldfein said: “I think right now if there is one message I want to get out to the force it’s that we did not stop, when we got back in the air and we felt like we identified subsystems that needed to be either upgraded or fixed, we didn’t stop there because that was not ‘root cause,’ ” Goldfein said.
“We kept going,” he said. “I wish it had not taken this long but, you know, we had to go down this path to get to this level of understanding.”
“Given the number of months it’s taken, I understand completely that they’re going to be a little bit skeptical at first.”
Gen. David Goldfein, the Air Force’s chief of staff, who says he has ‘high confidence’ that an investigation has learned why dozens of pilots have fallen ill in the air and said a fix is on the way.