I often see after a crash that people die unable to exit the aircraft. The news reports and passenger and safety organizations criticize the FAA for not having realistic emergency exit regulations. What determines the criteria for a plane being "safe" in an emergency?
2$\begingroup$ Is that really something you often see nowadays? I can think of AF358, OZ214 and EK 521 as the most recent major examples of how an aircraft can crash and yet have all the survivors evacuate safely. $\endgroup$– BenDec 13, 2017 at 2:16
1$\begingroup$ San Francisco - Asiana Flight 214 (2013) Boeing 777, the FAA was heavily criticized for evacuation standards en.wikipedia.org/wiki/Asiana_Airlines_Flight_214 $\endgroup$– jwzumwaltDec 13, 2017 at 2:49
Per 14 CFR 25.803:
For airplanes having a seating capacity of more than 44 passengers, it must be shown that the maximum seating capacity, including the number of crewmembers required by the operating rules for which certification is requested, can be evacuated from the airplane to the ground under simulated emergency conditions within 90 seconds
Appendix J to Part 25 specifies exactly how the evacuation tests should be done. It's too long to quote here, but it includes requirements for lighting levels, number of passengers, minor obstacles, infants on board etc.
I have no idea whether or not those simulated conditions are reasonable and effective, but they at least set a standard.
2$\begingroup$ I believe there were some questions here on the site about those evacuation certification tests, and the general theme was, yes, they are somewhat unrealistic, but they have to maintain a delicate balance between realism on one hand, and fairness, repeatability, and safety (e.g. on the A380 test, one volunteer broke his arm) on the other hand. $\endgroup$ Dec 13, 2017 at 8:56
2$\begingroup$ @Jorg - When I read the answer (Appendix J to Part 25), non working exits where not picked randomly, the aircraft is level, no smoke, and the mfg is allowed to have stairs for the wings. 3 infants. no children, and no injured, 1/2 the carry on baggage. Now I understand why people die! $\endgroup$ Dec 15, 2017 at 0:27
1$\begingroup$ @jwzumwalt: It's impossible to predict exactly how long passengers will have to exit a plane in future emergencies. In general, however, if plane #1 takes 85 seconds to evacuate everyone under test conditions and plane #2 takes 95 seconds, that would suggest that under emergency conditions, passengers would likely be able to exit plane #1 faster than plane #2. The time to exit under test conditions should be viewed as a ranking criterion, rather than having any particular numerical relationship to the time required to exit in an emergency. $\endgroup$– supercatFeb 13, 2019 at 17:49
$\begingroup$ @supercat - The problem is there have been a multitude of aviation accidents that have shown the emergency criteria used is unrealistic to actual emergencies. Even when an aircraft is exited without damage and all exits working such as US Airways Flight 1549 on the Hudson, the exit time was several times more than 90secs and 5 seriously injured passengers had to be accommodated. $\endgroup$ Feb 13, 2019 at 23:01
$\begingroup$ @jwzumwalt: The time it took to get all passengers off the plane was greater than 90 seconds, but the time available to get all passengers off the plane before it sank was also greater than 90 seconds. $\endgroup$– supercatFeb 13, 2019 at 23:12