Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Conflict Ground Conflict; Critical; Ground Event / Encounter Vehicle; Ground Incursion Taxiway
Flight Crew Took Evasive Action; General Physical Injury / Incapacitation
Human Factors
On taxi out ground traffic failed to give way to taxiing aircraft. First Officer saw this and applied brakes heavily. Ground traffic was right to left. Flight attendant was injured with the sudden stop. Returned to gate. First Officer applied brakes without saying a word. We discussed the issue. I relayed that a verbal warning should have been given [to me].
Normal pushback and engine start. Ramp cleared us to contact Ground Control. I noticed a white van was driving eastbound on the service road between taxiways. The van was not yielding to us and that caught me off guard. Collision looked imminent and I reacted by applying brakes. The van continued eastbound and I reported the incident to Ground Control. As I was talking to Ground Control; the Captain stopped the airplane and was talking to the cabin. I learned the #4 Flight Attendant was injured; so I got on radio #2 to tell [Operations] that we needed to return to the gate for a injured Flight Attendant. We taxied back to the gate and awaited ramp crew to park us. Once parked; paramedics attended to the injured #4 Flight Attendant and took her off the airplane.
A321 flight and cabin crews reported a flight attendant was injured during taxi out when the First Officer abruptly applied brakes to avoid a collision with a vehicle.