Originally Posted by
Capetonian
Pace
I understand what you are saying but how are you defining 'risk'? What do the stats tell you?
If the stats show that 1 motorbike journey in 100 ends in an accident, and 1 light a/c journey in 100 ends in an accident, are they equally 'risky'?
You could say yes, but then if the motorbike accidents result in death 40% of the time and the a/c accidents result in death 80% of the time, then flying appears more dangerous.
If you extrapolate it to passenger miles flown/driven, you will get yet another misleading statistic.
you are correct there are multiple ways to measure exposure and outcome, however, the outcome is normally standardised as Death directly related to the incident within a limited time (typically about 30 days). This data is reasonably available for cars, bikes, planes, horses etc. agreeing a consistent 'exposure' is not so easy.
aircraft do very well and horses very badly on a per mile basis. cars are exceptionally good on a per journey basis. however, on all measures I have seen developed world light aircraft are worse than developed world cars, and closer to bikes.
in the UK big airline jets are best, FAA operated corporate jets next, then aoc jets, aoc other (I believe then non AOC owner flown IFR), training, PPL operations, gliders and finally at a pretty shocking level gyrocopters (I can't remember where helicopters come in the list).
the group of owner flown IFR, training, PPL has a broadly similar rate of fatal accidents vs. motorcycles when looking at the sensible numbers of per hour, per mile, per journey (with journey least favourable and per mile most) (this is all from memory of various bits of academic analysis.