Originally Posted by
rylan
The big problem is that 90 seconds or whatever doesn't even have to be demonstrated by the airlines when they reconfigure aircraft, but just done via simulation or on paper. Anyone think about how the emergency evac time is effected by airlines cramming in more seats? Yeah, they didn't have to retest. Its a sure bet that if the FAA made airlines demonstrate evac time they wouldn't pass with the new high density configurations.
Interestingly, they actually certify with the maximum number of people onboard that the type certificate permits - which usually exceeds even Ryanair and Spirit's ambitions for packing in seats.
Take the A380, for example: a typical operator configures it to about 500 seats, give or take (538 for Air France, 407 for Korean Air). But the evacuation certification was done with 850 people. It's impressive to watch:
https://www.youtube.com/watch?v=XIaovi1JWyY
One thing I'd highlight here is that the 90 second time is a certification metric - for an aircraft packed to maximum capacity with able bodied passengers. In the real world, there's more complexity to the evacuation - if you have ten disabled or elderly passengers onboard, short of the flight crew tossing them down the slide like fish at a market, it's going to be pretty tough to get everyone out in 90 seconds. But it does set a benchmark that allows a standard goal across all aircraft types and helps ensure manufacturers include an appropriate number of exits.