Airbus: A380 has a weight problem

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GearDown&Locked - people usually escape from buildings by using the stairs. Slower than a slide but then again everyone doesn't need to be out in 90 seconds because buildings burn a bit slower than aircraft what with them usually being made of concrete and not loaded with fuel.


Notso Fantastic - glad someone understood the question! Since as you say the decision to evacuate must be made when "the risks associated with a decision to stay onboard start exceeding the risks of an evacuation" surely this balance will be different for the A380 than for other types (and is probably already different for a 747 than for other smaller types).

I have some concerns though that perceptions of the dangers associated with evacuation on the A380 may lead to decisions being made that are not entirely rational.

Here’s an analysis of the problem based on entirely hypothetical numbers…

Two hypothetical premises…

- With a stretched version of the A380 carrying 800 passengers perhaps you might expect one serious injury or fatality with every evacuation.

- With an evacuation delayed until fire or smoke has actually become detectable in the cabin perhaps you might expect 30% of the passengers to be seriously injured or killed (surely a passenger or cabin crew initiated evacuation will occur once flames are seen).

Now imagine yourself as PIC with some indication of a problem that could perhaps lead to a fire. Perhaps there is only a 1 in 100 chance that the problem will lead to a fire.

Option 1 – order an immediate evacuation as a precaution with the expectation that one person will be seriously injured or killed.

Option 2 – wait and monitor the situation knowing that there is only 1 in 100 chance of a fire developing.

The results of these courses of action…

Option 1 – one person seriously injured or killed.

Option 2 – 99 times out of 100 nobody is seriously injured or killed. But a 1 in 100 chance of 30% (i.e. 240) of passengers being seriously injured or killed. Consequently, the average of result of Option 2 is 240/100 = 2.4 serious injuries or fatalities.

So using these figures it’s always rational to accept the dangers associated with a precautionary evacuation.

Now before everyone starts rubbishing the specific numbers I’ve chosen – their just to illustrate a point. The point being that the specific numbers are important when it comes to determining what’s a rational strategy.