Not a propelling move at all. From what I understand, Tornado is essentially an air braked loco. Her driver would have full control of the brake, even if the traction power & brake pipe pressure would be being provided from the rear. Stop over complicating it! The rear driver would know where he was, and would regulate power accordingly. No radios required. As a previous poster has said, diesel locos have a Brake Pipe Govenor, which will take off traction power when the ABP falls below a given figure. ie if the driver on 60163 made an application, traction power from the back would cease. Just a slight observation - people driving trains, and managing operational situations, on the national network do know what they are doing. Please stop second guessing!!