I saw a comment that said the swiss cheese model didn't apply here. I think it is still relevant even if this is a tad outside what it was intended for. It attempts to minimise the possibility of a hole through the cheese by using actors, systems and processes. In this case the bloke pitched up with a piece of cheese with a hole he had bored all the way through it and made no attempt to hide it. Poor old Celia held it up to the light and looked through it "Oi mate, you've got a hole through your cheese" she said, or something similar. More than once. But there were no errors in the flight plan in that it was correctly filled out. The numbers were in the right places. Then apparently it is no-one's job in our safety conscious industry to stop the cheesemonger from taking off ! Not for the first time it seems the industry is saying "hmm - we never thought of that". It's difficult to put ourselves in the position of someone with no sense of self preservation - never mind the preservation of all the souls under their command. I'm not saying I know what can be done either - that will have to be decided by all the clever folk in the industry bodies that put the regulations together - but this was way too easy !