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Comment by exabrial | Hacker News Reader

My brother in law, aviation firefighter, said after a crash you have 15s to egress, that's it. There's not a lot of air in the metal tube you're trapped in, it'll fill with smoke and everyone will be disoriented. It's also a long way to the exits, and the average person in the exit row probably will be in shock and likely not operate the exit door immediately.

Absolutely incredible the fireball was put out in the flip, these people are so lucky.

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The standard time for evacuating an aircraft that has to be demonstrated for certification purposes is 90 seconds with only half of the exits usable. It generally helps that the fire is (at least initially) outside the cabin most of the time. But yes, I wouldn't bet on conditions in the plane staying survivable for 90 seconds in all cases.

yikes.

Sounds like plenty of time for me to get my bag, pull out my phone, and start texting

You'll never have a better chance to go viral!

Presumably it helped that they crashed into a thick pile of snow in freezing conditions - I imagine that would slow the spread of the fire.

But still, that’s astonishing footage in the Reddit post linked above. Incredible that no one died.

Also the wing broke off early so the plane continued away from the initial fireball.

And the fuel spilled both away from the fuselage and onto snow, which both kept the main focus of the fire away from people and limited development of the fireball as well.

Kerosene (Jet-A) is relatively nonvolatile and tends to burn most violently when dispersed in air. It's not quite as heavy as diesel fuel, in which you can extinguish a lit match, but conditions in this incident probably limited flame development considerably.

All that snow is going to do next to a jet fuel fire is create a lot of steam.

The crash kicked up a lot of snow into the air, making me wonder if that helped suppress the fireball, as it seemed to die down very quickly. On thing leading to me think this might have happened is video from the recent firefighting in California, where the spray from the firefighting aircraft seemed to snuff out the flames as soon as it descended into them, before it reached the ground.

...and absorbing lots of heat as it evaporates.

There's a reason water is used for firefighting.

A fire can be extinguished with diesel (jet fuel is pretty much just cleaner diesel / kerosene) in cold conditions, I know because I’ve done it.

It takes a fair amount of heat / pressure to ignite jet fuel, easier if it’s vaporised.

Why were you trying to extinguish a fire using diesel?

I would guess they were not trying to extinguish a fire with diesel and accidentally learned you could.

Indeed. It was about 0 degree Celsius, camping and we were trying to get a bit of a fire going for heat. I won't do that with petrol as I value my eyebrows, ended up having to thin the diesel a bit with petrol as we discovered splashing diesel on a small flame on damp wood doesn't help at all.

I say this half-jokingly:

If you're going to rip a wing off do it as early in the crash as possible so momentum will carry you past the fuel/fireball.

If fire develops when you've almost or completely stopped you are now involved in the fire and the fatality rate goes up dramatically.

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