Own Account Driver:
SImilar can happen with an artic trailer if it’s dropped high and the driver doesn’t realise the pin has rode over the top of the fifth wheel. If it’s on a slope when it airs up if the driver’s still on the catwalk it will roll into the back of the cab.In reality the main safety issue is excluding loading bays not ever dropping trailers on any kind of slope rather than always applying the parking brake per se.
Then surely the safest way regardless of slope is just to put the brake on every time? Then the gradient becomes irrelevant.
Personally I can’t believe I this day there’s not a system on the trailer that doesn’t snap a brake shut once the airline is off…