The average number of serious casualties expected from a launch or re-entry, a regulatory threshold conditioning the license before insurance is even considered.
Casualty expectation is a probabilistic quantity that aggregates, for a given launch or re-entry, the probability of failure at each instant of flight, the resulting debris dispersion and the density of the population overflown, to produce an average number of serious casualties expected. It serves as a licensing criterion rather than a communications figure: licensing regimes set a threshold below which a flight may be authorized, on the order of one ten-thousandth of a casualty per launch under American regulation, and that calculation drives flight corridors, maritime exclusion zones and launch windows. Its logic is that of an accepted collective risk rather than an individual one, which makes it counter-intuitive to the untrained reader, a figure far below unity denoting an expectation and not a certainty of no harm. For insurance it is the entry point of the third-party liability calculation, since the same modeling is used to estimate the maximum probable loss that sets the amount of cover the license requires.
United States commercial launch licensing rules, recast by the Part 450 rule published in December 2020 and effective from March 2021, condition authorization on meeting a casualty expectation threshold for third parties.
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