[SystemSafety] A different Historical Question

[Derek M Jones]

On 23/03/2017 09:55, nfr wrote:
> A paper, Breaking Through the 10e6 Barrier, by R.W. Howard, was published at the International Federation of Airworthiness Conference in Auckland

This looks like another one of those papers that is
rarely cited (13 on Google Scholar), but had a wide impact.

There is a non-digital copy in the national archives
http://discovery.nationalarchives.gov.uk/details/r/C5954355

Everything else is behind an academic paywall.

>
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> On 22 Mar 2017, at 17:20, SPRIGGS, John J <John.SPRIGGS at nats.co.uk<mailto:John.SPRIGGS at nats.co.uk>> wrote:
>
> Way back in the last millennium, someone did an analysis of aircraft accident data, selected out a set based on various criteria, such as ‘western built’ commercial air traffic in controlled airspace, etc., and came up with a figure for accidents per flight.
> On behalf of ECAC, someone applied an improvement factor, truncated the answer to two decimal places and declared a ‘safety target’ of better than 2.31x10^-8 accidents per flight.  At that time, it was conventional to assume an average flight is ninety minutes. This was applied to the result and rounded up to give a target of better than 1.55x10^-8 accidents per controlled flying hour.
> I used to have references for these things, but I have lost them (the ECAC targets are quoted in a document called ESARR4 which is still available despite being obsolete in the EU for over a decade). In particular I wanted a reference for the ninety minute flight convention.  This is because I have been shown a standard (not from the commercial air traffic domain) that takes the ECAC targets as the basis for arguing that the average length of a flight is 89.4 minutes, i.e. taking the truncated and rounded results as ‘truth’ …  I would like to challenge it with references.
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> John
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-- 
Derek M. Jones           Software analysis
tel: +44 (0)1252 520667  blog:shape-of-code.coding-guidelines.com