Date: 201707
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: Icing; Turbulence; Rain
Light: Night
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Engine Vibration Indication
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Weight And Balance; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed As Precaution
Contributing factors: Aircraft; Weather
Primary problem: Ambiguous

Narrative: We departed ZZZ 2.5 hours late after extensive on gate and taxi delays due to thunderstorms impacting the field and departure corridors. A Crew Critical Offtime (CCO) extension was required on our duty day in order to depart. A Take Off Go Around [power] takeoff with wind shear precautions was planned and executed. On climb out we remained IMC to cruise altitude; encountering rain and turbulence throughout the climb. No airframe icing was noted; but engine anti ice was turned on as Total Air Temperature (TAT) dropped to 10C. Engine AI was turned off at -40C TAT. Rate of climb was very low as we passed FL300; and ATC was advised due to less than 500 FPM climb rate. As we leveled at FL340; the engine ECAM page appeared with a 6.3 N1 vibration indication flashing. The First Officer (FO) retrieved the vibration checklist in the QRH and we reviewed it. With Auto Throttle off I cycled the thrust from idle to climb thrust. The vibration indicated 3.4 at idle and 8.0 at climb thrust. I sent this information to maintenance. Dispatch immediately sent a suggestion to divert. We descended to FL270 (for more airspeed envelope) and I continued to try other power settings with the same result. At high vibration both the FO and I noticed a distinct smell in the aircraft. The smell was also noted by a flight attendant in the aft galley.I requested a phone patch with maintenance. After discussing the issue with maintenance and dispatch I made the decision to divert. Dispatch sent landing performance and I gave the flight attendants a briefing. I made an announcement to the passengers and the FO coordinated a turn to ZZZ1. I decided to land overweight rather than remain airborne with an engine problem. We ran the overweight landing checklist and landed uneventfully.As we descended to warm air; the vibration indication returned to normal (0.0) so I suspect engine icing as the cause.Maintenance write-ups were entered for both the engine vibration and the overweight landing.


Second narrative: After leveling off at FL340 in IMC conditions (rain) and the engine anti-ice on; the Captain noticed a vibration advisory for the #1 Engine N1 being approximately 5.4 units and slowly climbing. All other engine indications were normal with no apparent airframe vibration or unusual sounds or smells. #2 Engine N1 Vibration (VIB) was under 1.0 units. Asked ATC for FL250 and began a descent. During the descent we ran the Eng - High Vibration; High N1 vibrations in flight; in icing conditions checklist. The Captain performed the ice shedding procedure on #1 engine; multiple times. As the throttle was reduced to idle the VIB indication would decrease slowly below 5.0 and then start to climb again. As the throttle was increased the VIB would rapidly increase; one time reaching 8.4 units; accompanied by a metal friction smell. We broke out of the weather around FL290 so we requested to level off at FL270. Ice shedding was done in and out of clouds. The #1 Engine VIB averaged 6.8 units. Captain was advised by maintenance to not continue the flight and land. Closest divert was ZZZ1. Coordinated divert into ZZZ1 for XYR. Ran the Overweight Landing checklist and requested landing data for XYR from Dispatch. Weather at ZZZ1 was VMC with light winds out of the southeast. During the descent; passing through 10;000 feet we noticed the #1 Engine VIB was under 5 units and then while on extended final at 4000 feet #1 Engine VIB indicated 0.0 units. The Captain made an uneventful overweight landing (147;000 Gross Weight); taxied clear and to the gate with normal VIB indications on both engines.I would suggest adding something to the Eng - High Vibration checklist providing more information on sounds/smells to expect. Maybe add a False Indication section to the Eng - High Vibration checklist. I wouldn't have done anything different based on all the information/resources available and used.


Synopsis: A320 flight crew reported that they had a very slow climb rate above FL300 and the engine ECAM page appeared with a very high N-1 vibration indication.