Airbus 318/319/320/321 Undifferentiated
Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 501
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL
Human Factors
I released flight in Operations and began my walk to the gate. At some point during my journey to the gate; our original aircraft was swapped and we were placed on Release 2. This aircraft had a maintenance deferral for an inoperative APU. As soon as I discovered the deferral; I called SFO Operations to coordinate for a ground pneumatic unit.Just as we were to begin the pneumatic ground start sequence; someone on the ground crew pulled the external power. We were then left with only battery powered equipment. I lost contact with the push crew. I began waving my arms at two individuals sitting in a baggage cart tug directly in front of the cockpit; hoping they could help get the push crew's attention; but their focus appeared to be concentrated on the cell phones they were looking at. I then opened my cockpit window and was able to attract the attention of a Supervisor and told him what had happened and requested that external power be reconnected ASAP.The actions of the ground personnel led to an unsafe situation. Disconnecting the external power without cockpit concurrence could lead to an electrical incident; not to mention; if this had occurred during the start; we would have had no way to monitor the conditions of the engine. Additionally; I would like to know why any ground personnel are allowed to be using cell phones on the ramp? Aren't there enough hazards present without being distracted by a cell phone?
Air carrier Captain reported that with an inoperative APU the ground crew disconnected external power before the start and had difficulty getting the ground crew's attention to reconnect.