B757 flight crew reported safely continuing to destination after experiencing loss of pressurization at cruise altitude.
Synopsis
B757 flight crew reported safely continuing to destination after experiencing loss of pressurization at cruise altitude.
Narrative
Operating Aircraft X from ZZZ1 to ZZZ. At show time Aircraft X had 2 open MEL's; one for the APU run light; the other for Pack Temperature Control System; which reduced the number of Packs to one. The single pack operation limited max altitude to 35;000 feet. FL350 is what the flight plan release had us planned. While cruising at FL350 there was several very quick EICAS messages that said R BLEED OFF. The message didn't illuminate long enough to trigger a master caution. Shortly after these messages the CABIN ALT HI Master Warning and discrete light illuminated. We looked at the cabin altitude controller. It showed that the cabin was in the ran of 12;500 feet and the rate showed a climb of 500-750 feet a minute. We immediately ask ATC for a decent to FL310 thinking the single pack operation couldn't handle the FL350. While approaching FL310 the cabin rate of climb still showed around 500 feet per min. At this time we donned our O2 masks. We continued to ask ATC for lower. We requested priority handling at this point to expedite our decent. Approaching FL250 the cabin still showed a continued climb. At FL190 the cabin started to stabilize at a zero rate of climb/decent. At 10;000 feet the cabin started a climb. At some point during the descent there was an additional EICAS that said CABIN ALT INOP. During this decent we found it difficult to communicate. While I continued to fly and monitor aircraft performance; the First Officer ran the corresponding QRH checklists. We leveled at 10;000'; removed our masks. We were well south of ZZZ2. At this point the situation was under control and not directed by a checklist to land at nearest suitable we asked company dispatch whether they wanted us to land at ZZZ2 or continue to ZZZ. We had plenty of fuel to continue to both destinations; also WX was not a factor. The company directed us to continue to ZZZ. We had a normal approach and landing at ZZZ and taxied to the ramp. Cause: Equipment malfunction Suggestion: Sometimes things break. Better maintenance.
Second reporter narrative
We had one operating pack. Right pack was MELed due to history of right pack temp eicas issues. We were limited to FL350. After 5 minutes at FL310; we were cleared to our filed cruise altitude of FL350. We had a quick flash of R ENG Bleed air off. Moments later we received CABIN Alt EICAS with associated master warning. After asking for a descent to FL310; we donned O2 masks. We established crew communications and communications with ATC. At 310; cabin rate of climb was still 500 to 750 feet climb and cabin altitude showed 12000 feet. We continued descent to a cleared altitude of FL250. We continued lower to FL190 and somewhere we had a CABIN ALT inop EICAS; which I performed QRH and moved cabin altitude selector to manual and closed outflow valve. We were cleared to 10000 at this point. As we were descending we did not see marked improvement to warrant any intermediate level off to troubleshoot as we were still on O2. Arriving at 10000; we stabilized the condition and cabin altitude decreased below 10000. We removed O2 masks and requested priority handling. We informed Dispatch. Asked if they us wanted to drop into ZZZ1 or carry on to ZZZ. Dispatch wanted us to continue to ZZZ. We had plenty of fuel. Wx was not a factor as both ZZZ1 and ZZZ showed favorable Wx. At some point at 10000 we received a flashing R Bleed Air Off light eicas with associated r bleed air valve light. We ran QRH and secured the R Bleed Air valve. We continued onto ZZZ. Executed an ILS approach to RWY XX. Uneventful landing. We did not request assistance. Cause: Combination of R pack and bleed air malfunction on the right system. Had a recent history of right pack temp eicas.Suggestion: I'm not sure if we were filed lower that cabin alt could've been better managed. Maybe we could've recognized the cabin alt higher than 10000 earlier but it's not in my scan.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.