Medium Transport
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem; General Maintenance Action
Human Factors; Aircraft
We were assigned an aircraft to take from ZZZ to ZZZ1 that had the BLEED 1 system on MEL. The FO and I discussed before departure in our threat based briefing about how the BLEED 2 system would have a hard time pressurizing the entire aircraft all the way up to our cruise altitude of FL XX0 and how we should make the climb as shallow as we could without exceeding VMO or any airspeed restrictions in order to help the BLEED 2 system pressurize the aircraft.After takeoff the aircraft was pressurizing normally but then somewhere around approximately 7;000 feet on the climb we noticed that the cabin altitude was increasing at about the same rate as our actual altitude and there was only about a 2;500 foot difference between the two. Knowing that only one bleed system was trying to pressurize the aircraft we continued with the hopes that it would catch up and pressurize normally.At 12;500 we got the Cabin Press warning so we leveled off and asked ATC for the lowest altitude they could give us; we were over the [name] Mountains at this time so the lowest altitude they could give us was 12;000 feet. At 12;000 feet the cabin pressure was holding steady at about 9;500 feet but wasn't increasing or decreasing any further.The FO and I discussed running and looked at the pressurization fail checklist but both agreed that the checklist was designed for a 2 bleed operating system and that this was a unique situation.At this point I called Dispatch and Maintenance to discuss the best plan of action; after some discussion Dispatch told us that we needed to return to ZZZ because we didn't have drift down performance for our route of flight at 12;000 feet. By the time this was decided we were almost on the other side of the mountains and I could see the town of [name] about 30 miles to the southeast of our position. My decision was to not turn around and cross the mountain range again at 12;000 feet without drift down performance. When Dispatch became aware of our position we both decided that the best plan of action was to continue to ZZZ1.We landed in ZZZ1 without any further incidents.In hindsight there are two things I wish I would have done differently. The first thing I should have done was to not continue over the [name] mountains with the pressurization not adequately pressurizing the aircraft. I think my continuation was due to the fact that I was unfamiliar with how the pressurization of the aircraft performed with only one bleed system operative and it was my first time operating the aircraft with that particular MEL. If I had it to do over again I would have asked for delay vectors while we waited to see if the pressurization would catch up with our altitude and that way I could have avoided crossing the mountains at an altitude without drift down performance and just returned to ZZZ.The second thing I would have done was to at least run the unpressurized flight checklist; it was a short flight with a very high workload and even though we were still partially pressurized it would have been a good checklist to run just to see if there was anything else we were missing.
Bleed 1 was consistently giving a #1 bleed hot caution on previous flights. Therefore; the bleed 1 source was placed on MEL. The only guidance from the MEL was that we shall not turn on the affected bleed valve. Climbing out of ZZZ; we were filed too FLXX0. Bleed 2 was on bleed 1 was off. Upon reaching 12;000 feet the cabin press master warning light appeared. We leveled off and descended to 10;000 feet. We contacted Maintenance Control and Dispatch. I took the radios and was already PF. Due to not having drift down performance and already being pass the mountains Dispatch and the pilots agreed that it was best to continue to ZZZ1 as we had a lot of fuel.   We noticed the aircraft was very slow at pressurizing during the climb we attempted to help the system by reducing the rate of climb. This seemed to have little affect. It was almost expected by us that the master warning would go off. Once it went off we noticed the aircraft was at 12;000 feet. But the cabin pressure was at 10;000 feet. So there was a small pressure differential. We therefore decided that we would not put the masks on as this would make commutation more difficult with each other and there was no need for an emergency descent. We descend to 10;000 feet as soon as possible this allowed the cabin to descent to 8;000 feet which was much more normal. We contacted Maintenance Control first as we knew what caused the problem. They advised us to call Dispatch. Drift down performance was not available for our altitude so by the time we contacted Dispatch we had passed the mountains and we agreed with Dispatch that it was safest to continue to ZZZ1. Due to the aircraft not pressuring and knowing the issue causing the problem we did not run the cabin press checklist as this would have advised us to turn on bleed 1 which is specifically what we were told not to do in the MEL. By descending down to 10;000 the master warning went away. We continued to ZZZ1 with no further issues.1) It's important to continually monitor the pressurization panel. 2) Maybe contact [Dispatch during preflight for other options]. 3) Knowing that if the bleed source is on MEL; we should expect the aircraft to not pressurize.4) I would not feel comfortable flying an aircraft with this MEL again unless we were filed below 10;000 feet know the system would not pressurize.5) The MEL was not clear on what to expect with this system inop.
Air carrier light crew reported a Cabin Press Warning EICAS message while crossing a mountain range on a one pack deferred flight. Flight crew completed an uneventful landing after developing a successful workaround.