Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Workload; Troubleshooting; Time Pressure; Distraction
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport
Aircraft
I was PF (Pilot Flying) and the Captain was PM (Pilot Monitoring). Due to wind shear we briefed a bleeds off takeoff as a threat. I wrote on my SID plate with the highlighter function 'BLEEDS' as a reminder to double check that we got them back on. I confirmed the bleed switch positions were on as we climbed above acceleration height. Climbing out of ZZZ through approximately 11;500 ft. we got a CABIN PRESS warning. We stopped our climb at 12;000 ft. advised ATC and requested a vector to turn us away from the mountains for our descent and were cleared to descend to 7000 ft. I called for the CABIN PRESS warning checklist and took over ATC communication while the captain worked through the checklists and other communication. We received further vectors and continued our descent to return to ZZZ.The APU Bleed was MELd by Maintenance while we were at the gate. Whether related or not it would have been a good idea to pay closer attention to the overall bleed air systems and we may have caught on earlier that something wasn't right.
[Requested priority handling] when we received a Cabin Press warning climbing through about 11;000 MSL. We stopped our climb (reaching 12000) and returned to field for landing. Takeoff out of ZZZ was non-standard due to windshear reported. We took off with bleeds off. After takeoff we turned bleeds back on but the aircraft failed to pressurize normally. After advising ATC; leveling; and turning away from rising terrain; we ran the appropriate checklists and returned for landing. Recommend taking closer look at the aircraft pressurization panel to ensure aircraft pressurization is performing properly.
Air Carrier Crew reported the aircraft failed to pressurize during initial climb. The aircraft return to the departure airport.