The US National Transportation Safety Board (NTSB) has asked the FAA to increase the length of the hoses that connect cockpit oxygen systems to the masks that airline crew don during cockpit smoke events per emergency checklists.

The recommendation, issued 12 August, is directly related to an in-flight cockpit fire on a United Airlines Boeing 757-200 that diverted to Washington's Dulles airport en route from New York to Los Angeles.

Although the fire was caused by faulty electrical connections on the windshield heating system, a problem that had been widespread on several models of Boeing aircraft and is the subject of an airworthiness directive, the NTSB is also concerned with problems the pilots had in dousing the fire.

"The captain reported that he left his seat because the flames were in front of him and he needed to immediately reach the fire extinguisher, located on the back wall of the cockpit next to the jumpseat," says the NTSB in the recommendation. "The captain stated that, as he moved toward the fire extinguisher, his oxygen mask and smoke goggles were 'torn off' because he had reached the end of the hose attached to the oxygen mask."

"He removed the fire extinguisher, put the mask and goggles back on, and discharged the extinguisher until it was empty," the report continues. "The captain reported that the fire was suppressed but reignited within seconds and that, as he moved toward the cockpit door to retrieve a second extinguisher from the cabin crew, his mask and goggles came off again. He retrieved the extinguisher, put his mask and goggles back on, and discharged the extinguisher, fully extinguishing the fire.

NTSB notes that the FAA had been alerted to the problem as early as 2007, but the agency had responded that flight crew oxygen masks were meant to be used "in the event of decompression rather than while fighting an in-flight fire", according to the recommendation. Rather than the stationary oxygen systems in the cockpit, the FAA recommends that pilots use portable protective breathing equipment (PBE) for fires both in the cockpit and the cabin.

"The NTSB clearly recognises that portable PBE is necessary equipment in combating an in-flight cabin fire but [believes] that it may be of limited use while fighting an in-flight cockpit fire when oxygen masks are available and likely already donned, in accordance with operator and FAA guidance," the recommendation argued.

Bolstering NTSB's argument is that pilots by regulation must be able to don oxygen masks in 5 seconds versus 11 seconds for a PBE, "a difference that significantly increases the time that a crewmember could be exposed to smoke and fumes".

Along with hoses that will allow at least one crewmember to reach the fire extinguishers or other safety equipment, the NTSB is also recommending changing the In-Flight Fires advisory circular to make it clear when pilots should use built-in versus portable breathing devices for cockpit and cabin fires.

Source: Air Transport Intelligence news