Originally Posted by
Semreh
I'm always looking for good examples where 'obvious' control measures are not as good as people expect: could you give me a pointer/link to the relevant research providing evidence that "there is 10% chance that duplicate inspection will not catch the fault". A quick Internet search hasn't given me any obvious candidates - and a lot of procedures are designed around (semi-)independent sign-off, as in: A does the job and logs it as done, B checks and logs that it has been checked. It's relevant in many areas, not 'just' aircraft maintenance.
I took it from my "Human Factors in Maintenance" training book, but unfortunatelly it only says it came from a 1960s research on work on electronic and missile systems, with no direct pointer to the research. I take it as such. In my 30+ years in aviation maintenance I was involved in more than one investigation, (politely said) where a maintenance incident was not prevented by duplicate inspection, so I can attest that such omissions are not extremely rare.