Below the flight deck level of one of those floating leviathans of the US Navy is hardly a challenge; below the deck level of one the the RN's little armoured rowing boats certainly would be though!
But this flypast was too risky to the guys in the downward firing seats, in my view. Although we did similarly stupid things many years ago with guys downstairs who didn't even have bang seats. 350 KIAS at 50ft across a certain East Anglian aerodrome's ASP springs to mind......in a Vulcan.
The Fairchild accident was the sad culmination of a pilot's career of known rule-breaking:
http://www.simradar.com/Feature/2317...child_AFB.html