chornedsnorkack,
As an ex-firefighter, experience (and some long forgotten theoretical stuff) tells me that yes, pressure will make a difference - put
partial pressure i.e. how much of that pressure is made up by oxygen, only takes effect at higher altitudes.
If you lower the pressure without changeing the partial pressure, e.g. by ventilating, the fire will flare (fair 'nuff, since lower presure will mean higher evaporation-rate = more gasseous contents in air = fire flares). Likewise, if you increase pressure by e.g. directing waterfog above the fire, you get a sh#tload of steam out of it (the figure 1680 ltr. steam per litre of water that evaporates completely springs to mind - anybody?). The generation of steam will both take a lot of the heat out of the fire and increase pressure, thereby smothering the fire. This method is useful if you need to put out class B fires but only have water available. But you gotta like saunas - if not, I wouldn't recommend it
If you lower both the pressure
and the partial pressure - as in an aircraft cabin at, say, 8000 ft. cabin altitude - the fire will die down, but not extinguish until very low concentrations of O2 are present. And then you'd have to allow time for the fire to cool, otherwise it would re-ignite as cabin altitude drops and partial pressure goes up. So if you only have the crew to worry about, dumping the cabin is prolly a good idea - we can sit for 120 min. with masks on before we really have to do something. In the cargo ATRs, that would be the idea - get FD on O2, accomplish QRH, then F/O would swicth to portable 02 full-face-mask and go firefighting. Ho-hum...
Re. staying in one piece on ditching - well,
afaik all aircraft with pod-mounted engines have shear-bolts in the struts that will allow the engines to break away rather than break up the wing on contact. The fuselage - depends on sea-state, wind direction & strength, if power & hydraulics are available before impact or not, and the skill of the crew. If all goes according to plan, see no reason why you shouldn't be able to keep fuselage fairly intact, and that should lead to a much more orderly evac, improving long-term survival chanches. But when you think of how willing some of the punters are to follow CC instructions, some will still try to swim to distant land, some will only cling to their family, some will overinflate their lifejackets, some will take off clothes in the wather, and some will not want to float face down in high winds. These people will die anyway within the first 15-20 minutes
PS - how many have practiced the ditching manoeuvre within the last 36 month sim-cycle? Some airlines seem to take it seriously, others adopt the "Nah, you'll never need it - here's another EFATO for you"-attitude.
Empty