Round numbers only: if the normal annual activity rate of a Tornado crew is 200 flying hours per year then the tolerable (according to RA1210) incidence of fatal mid-air collision, based on first-party casualties only, is one fatal collision per 100,000 flying hours (on the assumption that both crew are killed). This is 500 crew-years' worth of activity. If there are 50 Tornado crews at any one time, this is one fatal collision every 10 years.
Serious question.
Having abandoned such numerical assessments on legal advice (issued by DLS(RAF) in 1992), when did MoD start doing it again, and why?
RAF Cranwell and Controller Aircraft started including this in their training at the same time as the repeal of Section 10 of the Crown Proceedings Act (1947). The CAA the same year.