B757 Undifferentiated or Other Model
Communication Breakdown; Human-Machine Interface
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury; Ground Event / Encounter Loss Of Aircraft Control
General Physical Injury / Incapacitation
Human Factors; Aircraft
We were pushed back from the gate; I was starting the engines and the Captain was communicating with the push back crew. The brakes were set and after start check done. We talked about the takeoff data as it was unusual; requiring flaps 20 and packs off. Both of us were heads down looking at performance data for our planned unpressurized takeoff. I happened to look up and noticed we were rolling forward; announced we were rolling and simultaneously went for the brakes. The Captain also applied the brakes. The stop was not violent; but firm enough to knock a few of our flight attendants off balance. We called and checked that the passengers and flight attendants were all OK prior to taxiing. We took off and during the flight were informed that one attendants knee was hurt and that she was unable to walk well and sat for the duration of the flight.
With both pilots involved in post pushback activities they failed to note their B757 was rolling forward during engine start. When they both applied brakes to stop the movement several flight attendants lost their balance; one of whom during the flight suffered knee pain forcing her to remain seated for the duration of the flight.