The next thing is request for engineers and a air start out to the hold no doubt.
Would only be done on a/c with fully servicable APU, and Engineers do the headset anyway. Although if the trials are succesful and it does become the "norm" then there is no reason why they couldn't have ASU's out at the starting grid just incase - like having the de-icing rigs out on the de-ice pad.
They would need more staff, more tugs, more time, and no doubt on busy days aircraft taxiing behind the towing aircraft and would use more fuel??.
If it becomes the "norm" then everyone would be towing out, and the current plan is to use TBL tugs only as they can tow faster to minimise delays.
At a station like LHR, the time differences are probably not going to be noticable anyway as the queues are normally so long. It will just mean a/c spending less time sitting in the queues pumping out fumes into the atmosphere.
