Your Lordship
I've never known CAA Ops Inspectors to turn up unannounced. Others may have different experience.
Some operators have a lot more inspections than others. There may be a number of reasons for that. Often it's when the CAA has good reason to be suspicious about an operator, even though they can't prove anything - yet!
The UK aviation world is relatively small, especially the professional helicopter sector, word travels very quickly, and CAA personnel aren't deaf - well, not to that sort of thing anyway.
