I have almost done this myself. I once had a multiple alarm fire in Greenwich Village, with my unit then TL-18, and I was operating as the roofman/firefighter. The fire building I was on had a roof that ran deeper than the building next door. Fire vented out of the roof and when I went tried make a hasty retreat off the fire building roof, in heavy smoke, I was so far back in the fire building that if I had gone over the roof parapet, I would have fallen 5 stories. I tested the presence of the adjoining roof with a Halligan Hook and the tool fell into the rear yard of the adjoining building. I had to straddle the parapet wall until I reached a safe area were the adjoining roof, was down just a few feet from the fire building roof. I have been at fires where members have fallen through painted over glass skylights, fallen 2 stories down and elevator shaft and fires where a member operating a handline stepped backward out of stairway window and fell 1 1/2 stores into the trash filled base of the open airshaft. Fatigue from long term firefighting indeed makes these many types of injuries more common. Captain Bob Rainey FDNY Engine 25 retired