Surprised to see Apache being talked about. I seem to recall hangars full of them for months or years with no trained crew to fly them. Had it been a commercial procurement deal, everyone connected would have been visiting their jobcentre
Two main problems;
1. Training should not be considered part of ILS. If the LS date is (typically) 3 months before ISD, and it takes (say) 6 months to train a pilot, then pitching up with a sim 3 months before notional ISD is of no use. You need to get training away from the ILS mindset. To this end, procurement rules state the sim is considered the 3rd aircraft, after the TI and PI. The only person who can change this is the Service owner (the named individual who makes materiel and financial provision, and he'd only do it if, for some reason, there was more than one TI or PI). A simple rule which, if followed, removes so much risk. Show me someone in DE&S who knows this rule, never mind follows it!
2. Blind adherence to PFI dogma. Another concurrent programme in the same Directorate (which should be top of any such list!) was told to PFI its Trainer. The response was to fill in the waiver form, then forget PFI. How many Apache sims, at the same spec as ours, have been sold overseas? None? Then the waiver would have taken 5 mins and it would have been ready on time. They were told, but didn't want to upset the 2 Star. Apache is NOT a good example of how to run a programme.