I'm involved with Machinery Safety and have been looking at some ground support equipment that transfers ULDs. I am concerned about the work from height aspect, and wondered if there is any accident data available for this type of equipment.
Speak to the HSE. It's in their remit and they are currently having a poke at it all!!!
Do a search on their web site for 'airport GSE' and you'll find lots of stuff. I think the best person to speak to if you want more is Chris Barringer - she's very knowledgeable on the topic.