Question to the Ministry of Defence:

To ask the Secretary of State for Defence, pursuant to the Answer of 26 November 2014 to Question 215200, how the overall tolerability level was calculated; and how the figure of 0.84 per 1,000 was arrived at for the Tornado when the level for one primary accident set, mid-air collision, was 0.86 per 1,000.

The figure of 0.86 per 1,000 is derived from a 2012 Defence Science and Technology Laboratory report. This modelled an estimate of the expected future level of Tornado Mid-Air Collisions from 2011 through the remaining service life of Tornado GR4.

The figure of 0.84 per 1,000 uses a different metric, in accordance with the Military Aviation Authority Regulatory Article (RA) 1210 Annex A. This metric is the Rate of Death for Tornado GR4 aircrew based on actual historic fatalities covering all accident sets over a defined period, and is now used as the starting position for tolerability judgements.