Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport
Aircraft; MEL
Climbing through FL200 felt a pressure bump. We heard a 'flapping' sound and immediately had the EWD (Engine Warning Display) display the Pressure page and it was showing the cabin climbing at 4100 fpm+. That cleared itself and we both agreed to stop our climb at FL220. Selected the Pressure page and it showed the cabin still climbing at 500-600 fpm and the cabin altitude at around 4;500 feet. We watched it continue to climb and decided that there was a malfunction in the system but had no ECAM warning associated with it at that time. We decided the best course of action was to descend immediately and return to ZZZ. The First Officer was the Pilot Flying and he took control of the plane and the radios while I called the company (ZZZ Ops & Maintenance Control as well as the Dispatcher). I then notified the #1 F/A that we were returning to ZZZ and we had had a pressurization malfunction but to expect a normal flight back to the airport. The First Officer received a clearance to descend and a turn back to ZZZ. We prepared for a normal approach to [Runway] XXR and landed without further incident. Our landing weight was approximately 127;000 lbs well under our max landing weight. Cause - Simple mechanical malfunction. But a contributing factor might be that the aircraft had the left Pack on MEL.Suggestions - Again; this was just a mechanical failure that we had to deal with...you know FIX!
Climbing out of FL210 I noticed the cabin pressure was rising at a rate not typical to the aircraft. I (Pilot Flying) leveled off at FL220 to assess the situation. We determined there was a pressurization problem and the cabin altitude was continuing to rise. We advised ATC; requested a descent; and returned to ZZZ without further incident. The Captain and I worked well together using SOPs to determine the issue and make the right decision about how to safely get the airplane on the ground.
A319 flight crew reported a pressurization system malfunction in climb. Returned to departure airport and landed uneventfully.