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The first step in the "Smoke, Fire, or Fumes" checklist for any pressurized aircraft is for the crew to put on their oxygen masks and set them to EMERGENCY, so that the crew can breathe, and thus function well enough to execute the rest of the checklist.

However, it's possible on at least some aircraft for a fire to develop that intimately involves the flight crew supplemental oxygen system, as the hull loss of SU-GBP aka EgyptAir flight 667 at its gate in Cairo Int'l demonstrated dramatically. Fortunately for the EgyptAir crew, their experience happened with the aircraft squarely on terra firma, allowing a swift evacuation with only a few serious injuries. However, if a similar event happened while cruising over the ocean at 35,000', what could the flight crew do to avoid being incapacitated, considering that such a fire would render at least part of the crew oxygen system inoperable?

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    $\begingroup$ Isolate the main cylinders and saturate fire co2/haylon from the fire extinguishers. Oxygen in elevated concentrations will raise the heat and intensity of any fire in quite a spectacular manner. $\endgroup$
    – jCisco
    Nov 23, 2016 at 23:33
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    $\begingroup$ @jCisco Saturating fires with CO2 in a confined space seems very dangerous. Do they actually use CO2 for this on planes? $\endgroup$
    – David Richerby
    Nov 24, 2016 at 11:30
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    $\begingroup$ Similar event (probably; investigation still ongoing, but the similarity is significant) did happen while cruising over o̶c̶e̶a̶n̶ sea at 3̶5̶,̶0̶0̶0̶'̶ FL370, by coincidence also to Egypt Air, with predictably catastrophic results. $\endgroup$
    – Jan Hudec
    Nov 24, 2016 at 22:30
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    $\begingroup$ @DavidRicherby I'm not sure if CO2 based suppression systems or extinguishers would be available on a commercial passenger aircraft. Halon would be more suitable and safer primarily mitigating the reactivity, cold shocking risks to the aircraft and suffocation of the crew and passengers. $\endgroup$
    – jCisco
    Dec 5, 2016 at 14:12

1 Answer 1

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Opening the flight deck door may be sufficient in some minor cases at the expense of letting smoke and CO2 invading the cabin volume.

In serious cases: Protective breathing equipment is available in the aircraft:

enter image description here

Smoke hood demonstration video:

enter image description here

Portable oxygen cylinders and masks are also available, e.g. for A320 family:

enter image description here
(source)

The presence of this equipment is regulated, e.g. in US by 14 CFR 25.1439:

at least one portable protective breathing equipment shall be located at or near the flight deck for use by a flight crewmember.

In addition, portable protective breathing equipment must be installed for the use of appropriate crewmembers for fighting fires in compartments accessible in flight other than the flight deck. This includes isolated compartments and upper and lower lobe galleys, in which crewmember occupancy is permitted during flight. Equipment must be installed for the maximum number of crewmembers expected to be in the area during any operation.

The oxygen supply if for 15 minutes minimum:

The equipment must supply protective oxygen of 15 minutes duration per crewmember at a pressure altitude of 8,000 feet with a respiratory minute volume of 30 liters per minute BTPD.

These systems are already necessary to the cabin crew to fight any fire or help passengers in case of cabin depressurization.

If a safe aircraft state cannot be restored within the 15 minutes, then the fire is already uncontrollable. Over the ocean and too remote from usable airports, the crew would have to resign and ditch the aircraft to evacuate it, a last resort and risky escape action.

In the accident you mention:

  • The oxygen system involvement/malfunction is suspected but not certain.
  • Considering the damages to the flight deck and panels (seen below), a problem for pilots would have been to be able to fly the aircraft with missing or failed instruments and controls, in a hot flight deck atmosphere. The passengers and crews seem to owe their lives to the accident occurring on the ground.

enter image description here

(avherald.com)

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    $\begingroup$ While awful to wear the smoke hoods can be brilliant. My father-in-law is a firefighter and sister-in-law an ex air hostess so both have had training in them. They said there are several around the cabin along with portable oxygen supplies, which are used for any serious fire. $\endgroup$
    – Notts90
    Nov 24, 2016 at 9:28

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