js0798,
...and that is because the probability of one failure followed by a second from an unconnected cause ('a' followed by 'b') is 1 x 10**-10.
The issue, conveniently forgotten by AnFI, is not the probability of an engine failure – which remains constant at about 1 x 10**-5/hour - but the consequence of a failure if it occurs over a hostile environment (a hostile environment is where safe-forced-landing cannot be carried out – i.e. resulting in a catastrophic event).
What in fact is being advocated by js0798 is not flying a twin over the NP, but a single.
The statistics have not changed;they are just conveniently ignored whenever it suits for the purpose of recycling the argument.
... mathematically speaking!
Jim
Last edited by JimL; 27th December 2011 at 07:02.
Reason: Emphasis of the conditions of failure.