Ben's got it wrong - the escape hatch in the ATR isn't designed for passengers. It is within the cockpit - one has to throw out the rope and climb up 'stairs' on the side of the electrical racks. The cockpit is separated from the cabin by two locked doors.
In the freight world, surely this hatch would have been the quickest option for the crew to escape fire, even on 'land'. The other emergency exits are blocked by the freight and netting, the only other exit being the cargo door which would take a little while to open (an eternity during a fire!).
In case sierra's image a few posts above doesn't work for you (it doesn't on my mac devices), hopefully this will (from the avherald website):
