Unaware that the right engine was still running; awaiting ground power; the Gate Agent and Flight Attendant at the aft main door of a Q400 opened the door and deplaned passengers.
Synopsis
Unaware that the right engine was still running; awaiting ground power; the Gate Agent and Flight Attendant at the aft main door of a Q400 opened the door and deplaned passengers.
Narrative
When we arrived at the gate the seatbelt sign was turned off; but we did not receive the door chime. I could see the Ramp Agent pushing the stairs to the aft door; so I made the announcement that we would be deplaning out both the forward and aft exits. Although the door chime had not been given; the Ramp Agent opened the aft door and gave me a thumbs up to allow passengers to deplane. The pilots never told us to hold passengers and I could see that the 'A' Flight Attendant had opened the main cabin door; so I let passengers start to deplane. I did not realize an engine was still running due to problems with the APU. I was having trouble getting my ears to pop and could not hear very well. The ramp agents never told me to keep passengers on board. Even after the passengers started getting off; the ramp agents continued to unload bags. I didn't fully realize what had happened until we were in the taxi on our way to the hotel and Flight Attendant 'A' brought it up. We all should have communicated better and the aft door should not have been opened by the ramp until the engines were shut down and it was safe for passengers to deplane.We need to stress the importance of the ramp [personnel] being aware of what is going on around them. The ramp [personnel] are the eyes and ears for flight attendants as we can't always see or hear what is happening outside the aircraft. Also making sure the cabin crew is more observant; not always counting on the ramp [personnel] to give them accurate info.
Second reporter narrative
Opened main cabin door and found #2 engine still running in cool down mode. Did not deplane passengers until #2 engine was shut down. Observed passengers deplaning from back door of aircraft before #2 was shut down.Discovered GPU unit had not been properly hooked up to aircraft. Flight crew had shut down #1 [engine] and was waiting for ground crew to properly connect GPU; so they left #2 [engine] running in cool down mode much longer than normal. Flight crew shut down #2 [engine] upon learning main cabin door was open.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.