>By your logic death per miles travelled by different mode of transport statistics would be useless, too, precisely for the same reasons you are stating, that is needing to know how many miles you actually travelled using each mode of transport
Yes, if you want to calculate a lifetime risk, you must know (or estimate) a lifetime usage.
>So deaths per hours travelled is actually better.
It really isn't. Does the average person spend as many times more time in cars as planes are faster than cars? If so, per mile risks would be comparable to lifetime risks. The average person probably spends more time in cars than that, though that still leaves per mile risk as closer to accurate (for the average person. Are you the average person?). But neither per mile nor per hour risk should be conflated with lifetime risk, and if you're not going to use personalized assumptions about usage, it's much better to just look at actual mortality data to avoid the issue entirely. For most comparisons though, risk/cost/pollution/whatever per passenger (or for goods, ton) mile is probably by far the more useful measure. If something needs to get from A to B and you need to know what that entails or what the best option is, those are the more directly relevant figures.
Yes, if you want to calculate a lifetime risk, you must know (or estimate) a lifetime usage.
>So deaths per hours travelled is actually better.
It really isn't. Does the average person spend as many times more time in cars as planes are faster than cars? If so, per mile risks would be comparable to lifetime risks. The average person probably spends more time in cars than that, though that still leaves per mile risk as closer to accurate (for the average person. Are you the average person?). But neither per mile nor per hour risk should be conflated with lifetime risk, and if you're not going to use personalized assumptions about usage, it's much better to just look at actual mortality data to avoid the issue entirely. For most comparisons though, risk/cost/pollution/whatever per passenger (or for goods, ton) mile is probably by far the more useful measure. If something needs to get from A to B and you need to know what that entails or what the best option is, those are the more directly relevant figures.