B757-200
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Illness / Injury
Flight Crew Overcame Equipment Problem; General Maintenance Action
Aircraft
Had a MEL deferral for L engine N3 indication; and on climbout received numerous brief L ENG BLEED EICAS messages as the N3 indicator went to zero for a few seconds; then returned to normal reading. Eventually the N3 indication failed; and the L ENG BLEED EICAS came on and stayed on. We ran QRH for L ENG BLEED; and noticed cabin pressurization fluctuating somewhat; but functioning properly. Approximately 5 minutes later; passing FL300; the cabin pressurization failed and we got a cabin altitude warning horn and EICAS message. We performed the phase one procedures and immediately descended to 12;000 feet (for terrain). Both of us felt mildly hypoxic; but after a few minutes of breathing 100% oxygen we felt our SA (Situational Awareness) return and continued on to [destination]. Landed uneventfully. FO (First Officer) did a fantastic job.Apparent failure of the right PACK; or cabin altitude controller. TBD based upon maintenance findings.
B757-200 Captain reported loss of cabin pressure related to either pack or cabin altitude controller failure.