In early '65, just after I joined my first Squadron at St Mawgan, I found myself the junior member of a Board of Inquiry into an accident involving the "skates" used to move Mk. 2 Shackletons sideways into hangars. There was not enough room in the hangar to use a tow bar to move the aircraft off the skates once in was inside. A tractor was hitched to one main undercarriage leg with a chain, to pull it off. As it came off the skates it naturally rolled forward, at which point the airman in the cockpit was supposed to apply the brakes. In this case the aircraft did not stop, the propellers hit the back of the tractor, and the tractor driver bailed out just in time to avoid being crushed against the steering wheel. Bent props, shock loaded engine and a damaged tractor.
No-one had checked that the brake pressure was sufficient.