WASHINGTON — A recurring spate of pilots being impaired by lack of oxygen continues to baffle military and civilian investigators, who told a frustrated Congressional committee Tuesday that they know some possible reasons but nothing conclusive.
“Clearly something is wrong for these number of pilots having these number of incidents,” said Rep. Michael Turner (R-Ohio), chairman of the Tactical Air and Land Forces Subcommittee. “What should be happening so we can get these planes flying again and our people have confidence in the system?”
“There is something wrong with the systems that these pilots are relying on for their lives,” Turner said.
“This has got to stop. I don’t have confidence that we are getting near to that,” he said. “This should not be a research project, this should be a fix-it project — knowing that this started because pilots had to revolt and say I am not flying.”
Clinton Cragg, principal engineer at NASA Engineering Safety Center, told subcommittee members that investigations have failed to evaluate the system as a whole — the aircraft, the pilot and the environment — in an attempt to determine the cause of the so-called “physiological episodes” — while insisting that events be viewed as singular rather than related.
“An unacceptable number of physiological episodes will persist if there continues to be a piecemeal approach to human (safety),” he said.
The testimony occurred as the 19th Air Force’s fleet of T-6 trainers — both for students and instructor pilots — remained grounded after 13 unexplained events, such as hypoxia, were experienced in a single week in January, part of 21 since the start of the year.
Both the Navy and Air Force have had repeated groundings of aircraft over the past year — called an “operational pause” in military parlance. Last summer, Navy training pilots refused to fly because of the unexplained dangers.
Hypoxia is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. Hypoxia may be classified as either generalized, affecting the whole body, or local, affecting a region of the body.
“First and foremost, physiological episodes are a human phenomenon,” Cragg said. “Although the Navy has put significant effort into investigating the physiologic episodes, the bulk of their efforts to date have been directed to the aircraft rather than human physiology. Centering our investigation on the human element revealed new information about the character of physiological episodes.”
He said that the hypoxia causing most of the incidents can be explained by a combination of issues affecting the various stages of the oxygen delivery process, including those stages within the human.
Rear Adm. Sara Joyner, the lead on the Navy Physiological Events Action Team, told subcommittee members the Navy is “utilizing every resource available in our efforts to resolve these issues” and that “this will remain our top safety priority until we fully understand, and have mitigated, all possible PE causal factors.”
“We have implemented numerous technical and operational measures to mitigate the risk to our aircrew,” she said. “The Navy and Marine Corps are performing a variety of actions to prevent and mitigate the effects of PEs in our F/A-18/EA-18G and T-45 aircraft. These efforts focus on determining and removing root causes, promptly and reliably alerting aircrew when malfunctions occur, and providing effective training and emergency procedures to enable safe aircraft recovery.”
Joyner said the Navy has just started installing new sensors that will help provide data on pilot body reactions and functions and other data not previously available as one way to provide more insights to the problem.
“We have turned the corner on T-45. We have a long term goal to add a human integration system,” Joyner said. “The F-18 turning the corner and see now we can influence the pressure response on the aircraft.. long term design change sin places to further stabilize that system. We are open to adding things along the ways to make sure we are not missing anything.”
“We won’t stop until we resolve it,” she said.
One cog in the investigation: The Navy does not have complete information on how the pressure control works in the aircraft oxygen system because it was not part of the F-18 design data supplied to the Navy by Boeing, the manufacturer, Cragg said.
“They need to have that to trouble hoot,” he said. However since the F-18’s legacy system is analog, “you have to go find that” information he said. In fact, previous reports said the Navy may be required to purchase the data from Boeing.
In January, the Air Force assembled a team to look into the rash of hypoxia and other physiological events endangering the safety of pilots.
Brig. Gen. Bobbi Jo Doorenbos, who did not appear before the subcommittee, will head the team, according to an Air Force release.
“As part of the integrated effort to address physiological events, the Air Force is providing more resources to understand (incident), standardize response actions to such events and assess options for more robust aircrew training to recognize and respond to these events,” Doorenbos said in the release. “Our ultimate goal is to prevent (incidents).”
Air Force Lt. Gen. Mark Nowland, deputy chief of staff, operations, told the subcommittee that operating high performance combat aircraft, especially as aircraft age, will always carry some inherent risk.
“The overall the overall rate of hypoxia-like physiologic episodes occurring across the Air Force fighter and trainer fleet remains incredibly low. In fact, the probability of a fighter pilot experiencing a physiologic episode remains less than 1 percent per year,” Nowland said.
Nowland said Air Force investigations have concluded there is no single root cause tied to a manufacturing or design defect that would explain multiple physiologic event incidents. “Some events are due to issues outside the aircraft or equipment,” he said, “and some physiologic events remain unexplained and cannot be replicated.”
The subcommittee chairman was not convinced. “Gen. Nowland, I have to tell you, I could not be more disappointed by your presentation,” Turner said.