Originally Posted by Distant Voice
Do not follow your figures. How do you arrive at 100,000 flying hours based on the 1 in 1000 rate?
In hindsight the flying hours are a bit confusing and are not necessary to reach the 'one fatal collision every 10 years' conclusion:
Tolerable first-party fatality rate = 1 per 1000 population at risk per year (RA1210)
therefore
Tolerable number of first-party fatalities per year = Population at risk / 1000
which equals
(Number of crews * 2) / 1000
which equals
Number of crews / 500
If there are 50 crews then the tolerable first-party fatality rate is 0.1 crew per year, or one crew per 10 years.
The amount of flying that would be conducted in that period is:
(200 hours per crew per year)*(50 crews)*(10 years) = 100,000 hours