Does the FAA have or publish goal values for various risks?

I'm looking for something that says (e. g.) "We rate passenger airline flights as 'safe' if there are fewer than X casualties per million flying hours" or the like. Even better would be some kind of matrix reflecting "safe", "of concern", "hazardous", "dangerous", etc.

  • 2
    $\begingroup$ Possibly related: aviation.stackexchange.com/questions/46677/… $\endgroup$
    – Erik
    Commented Feb 27, 2020 at 19:33
  • $\begingroup$ @Erik that's more of a system level risk and failure analysis that drives system design. Mark is after more generic "public" risk factors I think. $\endgroup$
    – John K
    Commented Feb 27, 2020 at 21:56
  • $\begingroup$ I believe that what you are looking for relies on aviation's systems probability of failure occurrence. For instance, catastrophic failures that can lead to fatalities cannot occur more than 10e-9 per flight hour for commercial aviation. Does this answer your question? $\endgroup$
    – ppinto
    Commented Feb 28, 2020 at 14:57
  • $\begingroup$ @ppinto, I think that's what I'm looking for. Are these specifications published somewhere? $\endgroup$ Commented Feb 28, 2020 at 21:55
  • $\begingroup$ @MarkHarrison It can be found in standard ARP4761, page 14. I can prepare an answer to this question showing it. $\endgroup$
    – ppinto
    Commented Mar 2, 2020 at 6:59

1 Answer 1


"We rate passenger airline flights as 'safe' if there are fewer than X casualties per million flying hours"

I am not aware of any official FAA document that states such sentence. However, something similar can be deduced from safety requirements related to the development of aviation systems.

ARP4761 is a well-known standard for conducting safety assessments on civil airborne systems and equipment. A probability of failure occurrence associated with the severity classification can be found on page 14, which shows the following table:

enter image description here

As it can be seen, the maximum allowed occurrence of a catastrophic failure is 1.0E-9. Playing a bit with the numbers, this could be translated in:

Commercial aviation flights are considered as 'safe' if there are fewer than 1 catastrophic condition per billion flight hours

One could assume that a catastrophic condition can lead to fatalities, and this seems reasonable. But I'm afraid that this presumption is not written in official FAA publications (I might be wrong).

P.D.: Now, where these probabilities of occurrence come from is another interesting (and un-official) story, but I think is out of the scope of this question for the moment.


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