I saw the aftermath of an accident some years ago where a reach truck had tipped over forwards with the mast at around 6 metres, after the load guard at the top of the forks had struck a refrigeration unit on the ceiling of a cold store, due to the operator reversing back too far from a stack before stopping to lower the forks.

This truck had a heated cab so the operator was fully enclosed, but the longitudinal momentum caused the operator to fall against the windscreen during the overturn, pushing out the entire screen, and he fell through the window frame onto the mast, luckily crawling away unhurt just before gallons of acid started to pour from the battery, a very lucky escape!!