Last flight out one evening was a Skyvan on its way home to Belfast (company flight). I duly waited the 15 min then closed the airfield.
Next morning I started runway inspection and discovered an obstruction on the runway a short distance from where the Skyvan had departed.
It was a piece of perspex shaped just like a Skyvan window panel. Phoned Shorts and asked if they had inspected the Skyvan which had departed the previous evening and did they notice if it had something missing. They confirmed there was a hole where one of the fuselage windows should have been.
I dare say the crew wouldn't have noticed any increase in noise levels in the cabin; I don't know if they had any passengers on board.