Date: 202109
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Second aircraft: Widebody Transport
Aircraft component: Normal Brake System
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Situational Awareness; Communication Breakdown; Human-Machine Interface
Anomaly: Aircraft Equipment Problem Less Severe; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury; Ground Incursion Taxiway
Detector: Person Air Traffic Control; Person Flight Crew
When detected: Taxi
Result: Air Traffic Control Provided Assistance; Flight Crew Took Evasive Action; Flight Crew Returned To Gate; Flight Crew Requested ATC Assistance / Clarification; General Physical Injury / Incapacitation
Contributing factors: Aircraft; Procedure; Human Factors
Primary problem: Human Factors

Narrative: During taxi-out for Aircraft X; [the] Flight Attendant (FA) injured her left elbow by falling against a quarter-turn in the aft galley as a result of my Captain having to suddenly stop the aircraft in order to prevent a possible left wingtip collision with an aircraft on an adjacent taxiway. During taxi out of ZZZ; we were taxiing eastbound on Taxiway XX. We were instructed by ZZZ Ground Control to yield to an aircraft that was joining Taxiway XX on Taxiway XY coming from an eastbound taxi on Taxiway XZ. There was a Company Aircraft Y that was in front of us; joining Taxiway XY from Taxiway XZ at the conjunction of taxiways XX; XZ; and XY. I assumed that the Company Aircraft Y was the aircraft we were to hold for; as ZZZ Ground did not specify an aircraft type; e.g.; 787 or Airbus. Aircraft Y was far enough ahead and was not a conflict; so I continued to taxi on Taxiway XX towards Runway XXR; as our instructions were to taxi to XXR using taxiways XX and XX1.As we moved towards the conjunction of taxiways XX; XZ; and XY; I noticed an; up to this point; unseen Company Aircraft Z coming on Taxiway XZ from behind and to our left at a good pace; over my left shoulder view from the cockpit. I did not realize or expect that it was the aircraft that ZZZ Ground had instructed us to hold for; so I continued taxiing on Taxiway XX. Over the next few seconds; as we approached the conjunction of Taxiway XX and XY; I noticed the Company Aircraft Z on Taxiway XZ had caught up and was parallel with our aircraft; an A320; and was continuing towards Taxiway XY in order to join Taxiway XX in front of our aircraft.During this time; I instructed my FO (First Officer) to start the number 2 engine in order to be prepared for takeoff once reaching the runway. As such; he was heads down and did not notice the taxi conflict with the other Aircraft Z. Both aircraft were nearly at Taxiway XY when ZZZ Ground noticed the conflict and informed us that the Company Aircraft Z on our left was the actual aircraft we were supposed to yield for; vs. the earlier Aircraft Y. I noticed the Company Aircraft Z had initiated a turn towards Taxiway XY and as such; I ended up using firm braking in order to stop our aircraft in order to prevent any possible left wingtip conflict/contact; and in order to comply with ZZZ Ground instructions to hold short of Taxiway XY in order to yield to the other aircraft. During the braking maneuver; [a] FA (Flight Attendant) was facing towards the aft of the aircraft and lost her footing in the aft galley. She then fell backwards; towards the front of the aircraft; striking her left elbow on a quarter turn in the aft galley cart stowage area. Her impact with the quarter turn was hard enough to cause a painful injury to her elbow.I contacted the Purser and asked if the flight attendants were OK. I was informed that [the] FA was injured; and the nature of her injury was serious enough that we needed to return to the gate and to have medical personnel meet the aircraft. We coordinated with ZZZ Operations and returned to Gate XX; our original departure gate. We had paramedics; a Flight Operations Representative; and eventually an Flight Attendant Representative meet us. The paramedics tended to [the] FA and she was taken off the aircraft in their care. During the process; they had arranged for a replacement FA to work the flight segment from ZZZ to ZZZ1. I discussed the overall situation with [the] ZZZ Flight Operations Representative. I called the Chief Pilot and left a message with brief details of the incident. My First Officer and I made the determination that we were fit to fly the segment from ZZZ to ZZZ1. After further consult with [the] Flight Operations Representative and taking care of all necessary actions; we continued with the flight.




Synopsis: A320 Captain reported a Flight Attendant falling and getting injured during an abrupt braking to avoid a wingtip collision with another aircraft during taxi-out.