No different to a current ASU start protocol. They dont work behind any running plant.
Maybe the same in principle, but the layout of the servicing points would seem to reduce the safety of this operation. At the risk of getting rather off topic, it seems that this aspect of 787 ops is significantly non-standard. The 777 has a similar layout to all derivatives of the 737 and also the 767 and 757. The pneumatic connection is close to the fuselage centreline just aft of the leading edge of the wing root. The air cart is parked forward of the wing, on the LHS. I would expect the tug driver has good visibility of the ground staff and I imagine that the flight deck has visibility of the air cart.
For the 787 the aft electrical connection is under the trailing edge of the wing, significantly left of centreline. The power cart is parked behind the wing outboard of the engine.I understand from previous Boeing documents, when there were two aft connectors, that this design was for applying ground power during hangar maintenance. The aft connector is at 2.2m, the forward connector is at 2.7m. The steps can be seen on the photo I posted earlier.
My observations are that apart from being aft of a line drawn behind the tailpipe, instead of mid-engine, the ground staff are basically working in a blind spot. The flight deck may be unable to see if the power cart is clear. At a height of 2.2m, it is possible that steps may be required to remove the cable. the ground staff has to walk behind the main gear to retrieve the cable and steps. In my mind there is a risk of conflict, especially if the ground cart is removed and a worker goes back for the steps. It would require vigilance not to start push-back as soon as the cart is seen to move clear.
I am glad to see that the A350 have not broken with convention and has the air cart forward. I am aware that rear engined types such as B727, MD-90, F100 and the E-jets have the pneumatic below the engines, but still forward of the tailpipes.Hence, my question of do actual airline ops allow the use of this, or do operators accept the longer start time and dispense with the third power source.
The implications of trying to support this with fixed installations is even worse. Seems to be the option of either a ground pit, between the undercarriage track, or the use of a very long cable on an articulated system. Both with the inherent risk of ground damage.I would question if this is covered in AHM 33, Chapter 4 Ground Ops Manual, I only see references to ASU engine starts. Maybe you are right and everyone assumes that the protocol is the same, I see a few holes in alignment .