The head of the NASA team that reviewed the Air Force’s assessment of hypoxia-like symptoms with F-22 pilots said yesterday the service should conduct “end-to-end” testing of the jet’s systems that provide breathing air.
NASA Engineering Safety Center (NESC) Principal Engineer Clinton Cragg also told the House Armed Services tactical air and land forces subcommittee that the service should have completed this assessment during initial F-22 testing.
“Any change to a system should trigger the appropriate human-systems integration testing,” Cragg said in his opening statement. “Given the insights the Air Force has obtained this summer, we believe a fundamental reassessment of requirements and assumptions for the Life Support System in high performance aircraft should occur.”
Cragg specifically said the F-22’s Life Support System, Environmental Control System and Aircrew Flight Equipment need to be re-examined. NESC was asked to review the Air Force’s assessment and corrective procedures and Cragg said it supports the service’s planned corrective actions.
Cragg, USAF Scientific Advisory Board Aircraft Oxygen Generation Study Chair retired Air Force Gen. Gregory Martin, and Air Combat Command Director of Operations Air Force Maj. Gen. Charles Lyon also testified yesterday on F-22 pilot physiological issues. The Air Force July 31 blamed a faulty pressurization “schedule” in the F-22 for hypoxia-like symptoms and largely reiterated the same opinion before lawmakers (Defense Daily, Aug. 1).
The Air Force was scheduled to release a Scientific Advisory Board study yesterday on the F-22’s hypoxia-like issues.
Cragg also said a phenomenon known as normalization of deviance may have contributed to acceptance of F-22 hypoxia-like issues and the service should prevent it from occurring in the future. Cragg explained normalization of deviance as accepting a problem as a cost of doing business. In the F-22’s case, Cragg said the hypoxia-like symptoms and extreme fatigued experienced by pilots were written off as normal.
“You can almost fall into that mindset of where everyone says it’s normal, and especially with the F-22 being a top of the line Air Force fighter, everyone says you want to fly this fighter, (and) everyone says ‘yes,’” Cragg said, referring to pilots who were excited to fly the F-22 despite the physical symptoms reported. “Normalization of deviance is a cultural thing I think the Air Force needs to take a look at it and make sure it doesn’t occur in the future.”
The NESC team concurred that F-22 incidents were attributable to several factors:
· High concentrations of oxygen at lower altitudes can lead to “absorption atelectasis.” Atelectasis is collapse of lung tissue.
· Inevitable acceleration, which compounds the effects of high oxygen counts.
· Restricted breathing due to the inappropriate inflation of the upper pressure garment that not only prevented any relief of this atelectasis, but worsened the problem by reducing overall cardiac output.
· Contribution of uncharacterized F-22 Life Support System vulnerabilities, such as pressure drops across components in the cockpit.
The F-22 is developed by Lockheed Martin [LMT].