If you think the tax man will be happy at just getting a few quids from the agencies and Ryanair and get all sympathetic with the poor hard done to pilots because big bad MOL was beastly to them, think again. If you want to know the extent of an investigation do a search of any accountants forum, do a search of HRMC's site, there's enough stuff to keep you awake well past the next filing deadline. Knowingly filing fraudulent returns is a criminal offence. Try getting a disclosure Scotland after that.
Scaremongering, overly sensationalising ? Maybe, maybe not. Everyone knows the saying, death and taxes....