Pasir, I rather feel he was shooting you a line !!
Normal access was via the front door,which when moored is a step down from the launch.The rear door,never used it once in three years on the Sunderland.again does not need a ladder. The only ladder ever used ,was the mooring ladder clipped on the port side of the bow,to allow a crew member to grab the mooring strop off the buoy. It was then stowed inboard.Groundcrew working on the aircraft would use the front door as the front turret would be in the forward position on the trots.
He may of course been so enthralled to visit the Queen of the Skies, he stepped into space ?? Alternately,and to ruin the story,it happened ashore,when a ladder was used to access the front door. In which case he would have broken his bloody legs !! Smartly saluting erks !! I smell a porky.