Sometime ago whilst we were being loaded with mail the handlers came up to remove the tractor from the GPU. I'm not sure what kind of linkage there was between the GPU and the tractor but it was not properly disconnected.
As the tractor drove away it went very dark where we were sitting. (I should add that eating our "night mail sandwiches" was dodgy at the best of times but when you couldn't see which ones you were picking it was positively dangerous.) I looked up to see the GPU being trailed across the apron at high speed with the cable dragging behind it. As it passed the a/c on the next stand it eventually parted company from the tractor and freewheeled towards that a/c stopping just short of it. The tractor carried on oblivious to what had happened - only reappearing on the scene some time later.
Fortunately there was not much damage to the a/c and we were able to continue with the flight. In this particular instance the risk to the a/c parked next to us, and the loaders working in the area, was probably greater than the risk of damage to our own a/c.
I never heard anything back from the MOR which was filed.