Can't stop the engines!
An amazing thought had just crossed my mind. Imagine if the Iberia A340 runs off the end of the runway with full reverse thrust and the cockpit separates from the fuselage, as was the case in Toulouse.
This would certainly be a problem for evacuation, engines running with thrust both forward and aft direction and no way to stop them, as was the case in Toulouse. (they let the engine run the tank dry in order to stop).
Chances are good that they would suck up sand and dirt and stop, but the SAA flight, the engines were off the ground.
Food for thought!
A346 driver