A321
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Troubleshooting
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition
Aircraft
Level at FL340 on the RNAV arrival 15 miles from the ZZZZZ fix with a steady power setting; we felt a shudder and instinctively looked at the engine parameters. The Number 1 engine was about 2% below the Number 2 engine and increasing to match it. The EGTs were within normal tolerance and all other engine indications were within the normal range. We were unable to isolate the exact cause of the unusual vibration. The APU was started as a precaution. Descending through 7;000 MSL the aircraft began to vibrate. We were still unable to isolate the source of the vibration. [ATC was notified] and we requested RWY XXR. As we leveled at 6;000 MSL the vibration increased and we were able to confirm the source of the vibration was the Number 1 engine and that it was compressor stalling. The power to the engine was reduced to idle; the engine was operating without compressor stalling; and the vibration ceased. The engine was left in idle power for the approach. After landing the engine was shut down; the aircraft was inspected by the emergency response team; and we taxied to the gate.As a footnote: The [ARFF; Airport Rescue and Fire Fighting] team was not able to immediately come on to the runway. When I asked them for the inspection of the left engine they were still holding short of the runway and needed to get permission from tower before coming to inspect the aircraft.
A321 Captain reported high engine vibrations during descent.