Date: 201910
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: Turbulence
Aircraft: A321
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Situational Awareness
Anomaly: Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew FLC Overrode Automation; Flight Crew Regained Aircraft Control; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I was the Captain and was the Pilot Flying. It was a VFR arrival into Runway XX at ZZZ. 7 kts. tailwind on final. Calm winds on the Runway. 10 mile final; and held high by ATC on downwind. We were cleared for the visual approach to Runway XX and using the ILS as a backup for reference. We were slowing the aircraft and descending to the visual glide path at the same time. We arrived at 1000 ft. AGL stable and on glide path but the aircraft airspeed was not being managed and we initially didn't notice this. The airspeed was slightly above VREF (Reference Airspeed) but slowly decayed as though it were being properly managed in gusty winds (the tailwind made the power requirement near idle; the decay was slow). While the approach continued the airspeed slowed through VREF. Both pilots noted aloud that airspeed was not being managed. The aircraft did get below the ILS glide path but visually the aircraft was still in a position for a safe visual approach and landing. I disconnected auto-thrust and quickly recovered the airspeed. I continued to a safe normal landing. I'm not sure why this occurred. I may have not selected managed speed. It is a normal but not often occasion to descend to the glide path from above for a variety of reasons. In my opinion the aircraft was stable at 1000 ft. But the airspeed was not managed as it normally is. I was sure at the time that I selected managed speed on final approach. I'm writing this and will accept correction if I missed selecting managed speed and got into a sloppy condition on a demanding approach at my own doing. Also; a go-around was a quick thought at the time of the event but the aircraft recovered very quickly. And the thought left immediately.I consider this event to be one of those that just happens once in a while; not getting slow on final; but one where a pilot has to use his skill and experience to manage an approach with challenging circumstances. After the FAA examiner in the jumpseat noted the event; we attributed it to the aircrafts occasional inconsistencies when selecting certain modes. Very often they don't engage. He complimented our flight and left. I'm reminded that this airplane has modes that when not properly engaged; won't tell you they aren't engaged. Trust but verify.




Synopsis: A321 Captain reported decaying airspeed on approach while auto thrust was engaged.