Eric Greenwell wrote:
Chris Reed wrote:
It also means that over a 40 year soaring career your probability of
being in a fatal accident is around 1 in 50, or 2% - assuming you fly
the average annual amount of hours over the entire period.

9B


No, it doesn't. The risk isn't cumulative, it's 1:2,000 each year you
fly.
True, but 9B said "over 40 year soaring career".

I can guarantee that if you have a fatal accident in year 1, your risk
of repeating it in years 2-40 is 0%.
True, but irrelevant. I also calculate the risk over a 40 year period as
being 2%, assuming the 1 in 2000 chance/year. YMMV.

Chance of not being in an accident each year = (1 - 0.0005) = 0.9995
For 40 years, chance = 0.9995^40 = 0.98

That's 98% chance of not being in an accident. Lots of assumptions, so
maybe not too instructive.
For 40 years, 1 in 8000 gets it down to 99.5% of not being in an accident.

OK, I'll accept that as a calculation at the beginning of year 1.

However, I've survived 14 years without a fatal accident so far. In the
remaining 26 of my 40 year career (I hope), that gives me a 0.9995 to
the power 26 chance of a fatal accident (0.987, or a 1.3% chance). If I
make it to the end of year 39 I have a 1:2,000 or 0.0005 chance of a
fatal accident in the final year.

I don't think the probability over a flying career helps understand risk
much on an individual basis, though it's useful for insurers and actuaries.

Much better to think that you have a 1:2,000 chance in the coming year,
and work on getting that ratio to improve in your favour.