Date: 201908
Local time of day: 0601-1200
Flight conditions: VMC
Aircraft: A321
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Time Pressure; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; General Maintenance Action; General Release Refused / Aircraft Not Accepted
Contributing factors: Aircraft; Human Factors; Procedure
Primary problem: Aircraft

Narrative: Approximately 45 minutes after departing ZZZ we were in level flight at our cruise altitude of FL300; autopilot and A/T on; at a steady speed of .77/300 KIAS (right in the middle of the flight envelope). I was Pilot Monitoring and the First Officer was Pilot Flying. It was a beautiful morning with clear skies and no turbulence. Suddenly we had an ECAM message 'OVER SPEED' accompanied by flashing master warning lights and a continuous repetitive chime. We accomplished the FIX strategy; with the First Officer maintaining aircraft control. We initially crosschecked our airspeed indications; but all 3 were in agreement with no abnormalities. I verified that the flap handle was up and the aircraft indicated a clean configuration. The only ECAM procedure indicated was 'VFE....235'; which was obviously impossible at our altitude. We discussed the situation and decided to execute the Unreliable Speed Indication/ADR Check procedure in the QRH. The Pilot Flying disconnected autopilot; A/T and flight directors and we double-checked pitch and power; which were appropriate for our flight regime. We did not turn off any ADRs because all flight instruments appeared normal and I did not want to 'compound' the emergency by taking the aircraft out of normal law at that time. At no time were we within 15-20 knots of Vmax.We were able to silence the repetitive chime by pushing the EMER CANC button but the ECAM message and flashing master warning light remained. I instructed the Pilot Flying to declare an emergency and turn toward ZZZ2; the closest suitable airport. In coordination with ATC; he began a descent and slowed to 280 KIAS; then 250 KAIS at 10;000 feet. I notified Dispatch; the flight attendants and the passengers; then discussed an overweight landing with the First Officer. After slowing down; the OVER SPEED warning would intermittently extinguish for a few seconds and then return (again with flashing master warning lights and continuous repetitive chime). After evaluating all relevant circumstances I determined that it was safer to land overweight than to continue flight until at or below maximum certificated landing weight. Because the OVER SPEED warning was not associated with an actual over speed condition I was concerned about possible alternative causes (e.g. an ADR problem or other unknown malfunction) that could affect aircraft controllability. The First Officer flew a textbook ILS approach to Runway XXC and executed a flawless overweight landing (185;000 lbs.); touching down at less than 200 fpm rate of descent and delaying brake application (with the brake fans on the brake temperatures never rose above 150 [degrees] Celsius after landing). We taxied to the gate; shut down the aircraft and deplaned the passengers. Aircraft mechanics arrived and conducted over speed and overweight landing inspections; finding no damage. [Maintenance Control] decided that since no actual over speed had occurred; all that was required was to reset the warning system by lowering and retracting the flaps (which the mechanics did) and the aircraft would be returned to service. I discussed the matter with the [Maintenance Control] representative and expressed my concern that this would not identify or address the actual cause of the problem. [Maintenance Control] stated that the only way to troubleshoot the aircraft would be to download and analyze the FDR data; but that the required personnel and equipment were not available at ZZZ2. They offered to reset the ADRs and Flight Warning Computers instead. At this point I told [Maintenance Control] that I would not fly the aircraft again unless further investigation was done; and made an entry in the aircraft logbook to that effect. The First Officer and I subsequently requested to be removed from flight duty for the remained of the day.




Synopsis: Captain reported ECAM Message OVER SPEED with all three airspeed indication reading no over speed; diverted for a precautionary landing at an airport without the technicians or equipment available to return aircraft to service; so flight crew refused the aircraft.