Date: 202107
Local time of day: 1201-1800
Location: ZZZ.Tower, US
Flight conditions: VMC
Light: Daylight
Aircraft: A321
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Cockpit/Cabin Communication
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Troubleshooting; Distraction
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; Flight Crew Overcame Equipment Problem; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: I was the Pilot Flying on Flight XXXX; ZZZ to ZZZ1; DATE. All was normal until takeoff roll. At approximately 110 kts a loud signal began blaring in the cockpit. ECAM was clear of any messages and master caution/warning lights were extinguished so I elected to continue the takeoff. When the After Takeoff Checklist was completed we [advised] with Tower and told them we wanted to return for an immediate landing. I had two jumpseaters that flew the A321 and they were essential assets. They assisted in determining the source of the loud sound which was the EVAC Command Signal and the EMER CALL buzzers going off continuously. Neither the signal or buzzers would silence. Jump seater 1; Captain NAME1; covered the EVAV speaker with his hand trying to muzzle the sound and provided valuable input. I transferred the aircraft to the First Officer and determined that the cabin inter-phone was inoperative and was not able to communicate with the cabin. I directed the jump seater 2; First Officer NAME1; to open the cockpit door and establish communications with the flight attendants and asses the conditions in the cabin. He reported that passengers cabin lights; emergency exit lights; and lavatory smoke detector lights were intermittently blinking on and off. I told him through the cockpit door to tell the flight attendants that we were returning to land and not to evacuate and for the passengers to remain seated once the aircraft stopped. I took back control of the aircraft and we accomplished an over weight landing. After stopping and consulting with the AARF commander we determined it was safe to taxi to the gate. Signal continued to sound until maintenance showed and pulled circuit breakers at the gate. The assistance of my First Officer along with the 2 jump seaters was absolutely essential in successful conclusion to this event. During the event; my confusion of what was actually happening might have been mitigated by a deeper understanding of the CIDS (Cabin Intercommunication Data System) system.I feel that having better systems knowledge would be beneficial to any similar future events.


Second narrative: I was the Pilot Monitoring on FLT XXXX; ZZZ to ZZZ1; DATE. All was normal until takeoff roll. At approximately 110kts a loud signal began blaring in the cockpit. ECAM was clear of any messages and master caution/warning lights were extinguished so Captain opted to continue the takeoff. When the After Takeoff Checklist was completed we advised with Tower and told them we wanted to return for an immediate landing. We had two jump seaters that flew the A321 and they were essential assets. They assisted in determining the source of the loud sound which was the EVAC Command Signal and the EMER CALL buzzers going off continuously. Neither the signal or buzzers would silence. Jump seater 1; Captain NAME1; covered the EVAV speaker with his hand trying to muzzle the sound and provided valuable input. I transferred the aircraft to the First Officer and determined that the cabin inter-phone and PA was inoperative and was not able to communicate with the cabin. I directed the jump seater 2; First Officer NAME1; to open the cockpit door and establish communications with the flight attendants and asses the conditions in the cabin. He reported that passengers cabin lights; emergency exit lights; and lavatory smoke detector lights were intermittently blinking on and off. Captain told him through the cockpit door to tell the flight attendants that we were returning to land and not to evacuate and for the passengers to remain seated once the aircraft stopped. Captain took back control of the aircraft and we accomplished an over weight landing. After stopping and consulting with the AARF commander we determined it was safe to taxi to the gate. Signal continued to sound until maintenance showed and pulled multiple circuit breakers at the gate.Causal factor was a failure of CIDS computer. Maintenance has to research more causal factors on their end.Procedure on ECAM for CIDS computer failure. Nothing was displayed in ECAM during entire event.


Synopsis: A321 flight crew reported CIDS failed on takeoff; sounding simultaneous alarms causing an Air Turn Back and precautionary landing with assistance of two jump seaters.