Medical Official Explains F‑22 Pilot-protection Efforts

WASHINGTON, May 9, 2012 — The Air Force has insti­tut­ed mea­sures designed to pro­tect its pilots, ensure mis­sion com­ple­tion and assess the pos­si­ble phys­i­o­log­i­cal effects of fly­ing the F‑22 Rap­tor fight­er air­craft, the com­mand sur­geon for Air Com­bat Com­mand told reporters here today.

“The health and safe­ty of our pilots — all of our pilots — is the utmost pri­or­i­ty,” Air Force Brig. Gen. (Dr.) Daniel O. Wyman said. “Our oper­a­tional flight sur­geons and med­ical staff inter­act with our pilots on a dai­ly basis, and mis­sion No. 1 is their health and safe­ty.”

Before resum­ing F‑22 flights in Sep­tem­ber 2011 after a safe­ty stand-down, Wyman said, offi­cials col­lect­ed base­line blood sam­ples and pul­monary func­tion tests from every pilot.

“We had every pilot go through retrain­ing with the reduced oxy­gen breath­ing device so that they would expe­ri­ence and know their own spe­cif­ic ‘hypox­ia symp­toms,’ he said, adding that the com­mand also incor­po­rat­ed a pilot pulse oxime­ter and the C2A1 fil­ter as pro­tec­tive mea­sures.

Designed and cer­ti­fied by the Defense Depart­ment for the chem­i­cal war­fare envi­ron­ment, Wyman said, the C2A1 fil­ter can­is­ter was incor­po­rat­ed into the pilot’s life sup­port sys­tem to fil­ter any poten­tial con­t­a­m­i­nants from the air they breathed. The fil­ter has been test­ed against mil­i­tary and Nation­al Insti­tute for Occu­pa­tion­al Safe­ty and Health pro­to­cols, and found to be effec­tive against a num­ber of dif­fer­ent chem­i­cal war­fare and indus­tri­al chem­i­cals, Wyman said.

“It was cleared for flight use by the U.S. Air Force pro­gram office, and has been used by the mil­i­tary for over a decade in the ground crew and air­crew ensem­bles,” he added.

For each flight, the pilot would receive a new C2A1 fil­ter con­sist­ing of a high-effi­cien­cy par­tic­u­late, or HEPA, air fil­ter and acti­vat­ed car­bon and char­coal, Wyman said, and they turned in the fil­ters at the end of each flight.

Once fly­ing resumed, Wyman said, a black dust was found in some of the breath­ing hoses near the C2A1 fil­ter.

“We ana­lyzed it and found it to be acti­vat­ed car­bon dust … an inert or non­re­ac­tive com­pound that has been used for air and water fil­tra­tion for decades with­out any sig­nif­i­cant evi­dence of harm,” Wyman said.

Fil­ter test results indi­cat­ed the amount of acti­vat­ed car­bon dust lib­er­at­ed dur­ing nor­mal use was well below the indus­tri­al hygiene stan­dard lev­els set by gov­ern­ment agen­cies, the com­mand sur­geon said. Thir­ty pilot throat swab sam­ples exam­ined by elec­tron micro­scope also indi­cat­ed no evi­dence of acti­vat­ed car­bon, he added.

Still, some Rap­tor pilots have report­ed suf­fer­ing per­sis­tent cough­ing, which Wyman main­tained may stem from high con­cen­tra­tions of oxy­gen while under­go­ing spiked G‑forces dur­ing maneu­ver­ing. These con­di­tions, he said, may result in adsorp­tion of the oxy­gen — adhe­sion of a small lay­er of mol­e­cules — and sub­se­quent micro­col­lapse of some of the small air sacs in the lungs.

“Cough­ing is a nat­ur­al phys­i­o­log­ic response that serves to re-inflate the air sacs,” Wyman said, not­ing the con­di­tion typ­i­cal­ly occurs fol­low­ing the flight and is brief in dura­tion.

Air Com­bat Com­mand has imple­ment­ed a “rec­og­nize-con­firm-recov­er” approach to for­ti­fy safe­ty mea­sures, Wyman said. In addi­tion to train­ing that helps ensure pilots can more read­i­ly rec­og­nize hypox­ia or hypox­ia-like symp­toms, fliers can also pull an emer­gency oxy­gen ring, then descend to an alti­tude at which hypox­ia would not occur, he said.

Wyman stressed that the com­mand will con­tin­ue to eval­u­ate for oth­er poten­tial con­t­a­m­i­nates or envi­ron­men­tal or air­craft sys­tem fac­tors through the use of sen­sors and oth­er col­lec­tion devices. No root cause has yet been dis­cov­ered, he said.

“Every step of the way dur­ing the F‑22 return-to-fly, we have worked with our pilots and all of our per­son­nel involved to inspect the fleet, train the force, pro­tect the crews and col­lect and ana­lyze data,” Wyman said.

U.S. Depart­ment of Defense
Office of the Assis­tant Sec­re­tary of Defense (Pub­lic Affairs)