B787 Dreamliner Undifferentiated or Other Model
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 163; Flight Crew Total 7215; Flight Crew Type 2753
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed
Aircraft
Normal ground ops and departure from ZZZ. MEL item lower recirc fan all other systems normal. After level off at FL330 entering ETOPS; PM noticed cabin altitude at 8600 ft.; steady increase at 100 ft./min. Cabin alt was amber; no other EICAS or cautions. Differential pressure was 6.5. Captain/Pilot Flying called Dispatch/ [Technical Operations Maintenance Control]; unable to rectify issue; Dispatch concur with air return. Relief pilot recalled to flight deck; Pilot Monitoring request clearance for return to ZZZ while [Relief Pilot] ran QRG divert checklist. Captain ran TEST checklist; briefed approach; flew normal landing.
Flight Crew reported loss of cabin pressurization control; resulting in an air turnback.