Speaking as a supervisor of people which operate such equipment, I can give you several responses.
1. Driver: "I didn't know I was by a loading dock." or "I forgot it was there." or "A bee was buzzing around my face so I didn't see it (real one)." or "The sun was in my eyes." or "The damn thing went into forward all by itself." or "I thought I left it in neutral with the parking brake on (another real one)."
2. Safety Office: "You should have had gaurd rails up, and signage warning of the drop off."
3. My Management: "Take that person for a post-accident Urine Sample collection, then prepare appropiate corrective action. Make sure you include this on your scorecard because this was your fault in the long run."
