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Comment by InclinedPlane | Hacker News Reader

It doesn't matter why they have them, the fact that they are there changes the overall risk equation for the aircraft. Many military planes have bailout procedures because everyone has ejection seats or parachutes. Civilian planes universally do not. What is an acceptable risk in one circumstance is not necessarily acceptable in another.

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Therefore, as with civilian planes there is usually no "plan B" (exception https://en.wikipedia.org/wiki/Cirrus_Airframe_Parachute_Syst... ), acceptance criteria for unstable civilian aircrafts must be more strict than for military aircrafts.

E.g. higher redundancy of HW & SW, stricter testing/checks/validation of flight envelopes, more feedback to the pilots about why a computer is performing certain actions, etc... than military aircrafts using the same systems.

> Many military planes have bailout procedures because everyone has ejection seats or parachutes.

Do any modern military non-fighter jets have bail out capabilities? It was my understanding that you couldn't even put on a parachute in flight to jump out. You either had an ejection seat, or no capability at all.

The B-1, B-2, and B-52 bombers all have ejection seats. Some other combat aircraft, like the AC-130, have bailout procedures and the crew usually all has parachutes. Almost all other planes are either fighter jets with ejection seats or transport aircraft which are substantially similar if not identical to civilian aircraft in terms of dynamical stability.

It does matter why they have them, if you're using their having them as evidence that something else is a problem.

Swap out "instability" for "drab paint jobs" and see:

> I disagree that "drab paint jobs are not a problem". In military aircraft that have drab paint jobs it's common for everyone in the plane to be in an ejector seat or to have a parachute. Can you provide statistics on how many (or what proportion of) military planes with inherent drab paint jobs routinely carry passengers without parachutes?

Yes we can make an argument incoherent by swapping words in and out.

In this case the argument is not that a is evidence of b, it is that a ameliorates b. And that the risk of b is therefore priced differently where a is also present. So where a is not present, we must price the risk differently.

How that assertion relates to the historical record may be of interest.

Risk is assessed on a case by case basis. When people ask "is the risk of this system acceptable given its mission role" the answer depends on all of the characteristics of the system. In the case of military aircraft that means that both the fact that the airframe may be dynamical unstable in flight and that every crew member has an ejection seat are taken into account. And whether or not the plane is expected to be used in a combat environment will play a huge role in the acceptable levels of risk as well.

To blithely say "oh well, military planes do X so X must be fine for civilian aviation as well" is either intellectually dishonest or fundamentally naive.

It strikes me as unlikely that the military is taking the attitude "it's OK if our planes fall out of the sky during normal operation, because we have ejection seats".

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