Date: 202107
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Aircraft: A319
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ1
ATC / advisory: Center ZZZ
Aircraft component: Air Conditioning and Pressurizaton Probes & Sensors
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Workload; Troubleshooting
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Just prior to push out of ZZZ we received and Air Bleed Message. Maintenance interrogated the system and MEL'd the message iaw MEL XX-XX. Enroute the Purser called and stated 'we have an issue; in reviewing our manual we have a Class A fume event in the forward galley. It smells like dirty gym socks.' I've had fume events in the past and I know the ramifications to the safety of the crew and passengers. We also have received good training during [Flight Attendant Training]. In the cockpit we didn't smell anything. All three flight attendants confirmed the same smell. With a Jump seat rider in the cockpit; I made the decision to take a quick bathroom break. Upon reaching the front right galley is was prevalent; mild and persistent. Upon returning to the cockpit I had the purser remain in the cockpit. I used air cell to call Dispatch and maintenance. With pilots; purser; dispatch and maintenance all on the phone call we jointly made the decision it's best to divert to a suitable airport. Over the vicinity of ZZZ2 and ZZZ3 we evaluated diversions to outstations; continue to ZZZ4 or ZZZ5. We were 570 miles from ZZZ4 and 240 from ZZZ5. Knowing ZZZ5 was just as close as spiraling down from FL380 and the aircraft would be grounded; we took into consideration passengers re-accomodation; medical response; inflight support and aircraft replacement. ZZZ5 was the best option and the joint decision was made to proceed to ZZZ5. I asked the First Officer (F/O) to [request priority] from ATC and we proceeded direct to a fix on ILS [Runway] XXR and landed and taxied to the Gate. With the jump seater being pregnant and the review of other events where fumes become hard to smell after long exposure; I requested everyone in cockpit to wear oxygen. I ran through QRC and [other procedures] multiple times to make sure we didn't miss any steps. Managing and reassessing the issue I think we did a pretty thorough job. I even turned on APU and ran bleeds to trouble shoot and nothing was working. The smell persisted in a mild to moderate amount especially in descent according to Flight Attendants (F/As). The purser had F/As rotate to mitigate one persons exposure. With a full aircraft we couldn't move anyone. Upon landing and shutting down we de-masked and opened up flight door. The first officer immediately noticed the smell and we left shortly after securing the aircraft.  I was not aware that the F/As had on the previous leg noticed any smell. They all reported after the event that the dirty socks smell was present on the previous flight. When I took over the aircraft I was again blind sided by this. The F/A in aft galley even said she replaced her socks thinking it was her feet. So my suggestion is to continue to encourage communications from the cabin and have these experiences validated and documented even if there is the slightest question to certain smells. I don't know if the Air Bleed message would have an impact on this event but if so maybe adding instructions to confirm with crew no odors prior to MEL. Having these Name (Purser) able to locate his references on his tablet was huge in assisting me with my QRH.


Second narrative: In cruise Flight Attendant (FA) reported odor in galley. Ran QRH odor in cabin; Captain (CA) Flight Attendant (FA); Dispatch; Maintenance Control agreed best course of action divert to ZZZ5 as best suitable airport for landing. Received priority diverted direct ZZZ5; landed without incident.


Synopsis: A319 flight crew reported a fume event occurred during cruise; resulting in a diversion.