Narrative:

Reviewing the aircraft logbook; we were aware of 2 previous write-ups describing the pressurization panel automatic fail light and altitude windows digits flickering; but pressurization working normally. Both write-ups were addressed by maintenance and cleared. The flight from was uneventful. We kept a watchful eye on the pressurization and controller; and it functioned normally. Our departure from ZZZ was uneventful. Again; we monitored the controller and cabin altitude carefully during the climb. Everything appeared to be on schedule until around FL350. We then noticed that the cabin was climbing just a little bit higher than scheduled (around 8000 ft). As we approached FL370; the pressurization controller altitude digits and lights began to flicker as per the previous write-ups. As we had reviewed the QRH procedure; we checked to see if any of the EFIS-related symptoms were evident. They were not. We then noticed the cabin was between 8500-9000 ft. It became apparent that the cabin was not going to stop climbing; so we began to accomplish the checklist by selecting the altitude controller which had no effect. The cabin altitude continued to rise; with the horn sounding at 10000 ft cabin altitude. Captain (pilot monitoring) directed a descent; and coordination with ATC; declaring an emergency. With clearance; and the cabin altitude at approximately 11000 ft; first officer (PF) began the emergency descent procedure. We donned our oxygen masks; and started down to 10000 ft MSL; and back towards shore. While descending through FL270; the cabin altitude reached just over 14000 ft and the passenger emergency oxygen masks deployed automatically. Once established in the descent; we were able to use manual control to control the cabin somewhat. The cabin altitude didn't get much above 14000 ft -- we estimate 14500 ft.

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Original NASA ASRS Text

Title: B737-800 FLT CREW HAS LOSS OF PRESSURIZATION DURING CLB.

Narrative: REVIEWING THE ACFT LOGBOOK; WE WERE AWARE OF 2 PREVIOUS WRITE-UPS DESCRIBING THE PRESSURIZATION PANEL AUTO FAIL LIGHT AND ALT WINDOWS DIGITS FLICKERING; BUT PRESSURIZATION WORKING NORMALLY. BOTH WRITE-UPS WERE ADDRESSED BY MAINT AND CLRED. THE FLT FROM WAS UNEVENTFUL. WE KEPT A WATCHFUL EYE ON THE PRESSURIZATION AND CTLR; AND IT FUNCTIONED NORMALLY. OUR DEP FROM ZZZ WAS UNEVENTFUL. AGAIN; WE MONITORED THE CTLR AND CABIN ALT CAREFULLY DURING THE CLB. EVERYTHING APPEARED TO BE ON SCHEDULE UNTIL AROUND FL350. WE THEN NOTICED THAT THE CABIN WAS CLBING JUST A LITTLE BIT HIGHER THAN SCHEDULED (AROUND 8000 FT). AS WE APCHED FL370; THE PRESSURIZATION CONTROLLER ALT DIGITS AND LIGHTS BEGAN TO FLICKER AS PER THE PREVIOUS WRITE-UPS. AS WE HAD REVIEWED THE QRH PROC; WE CHKED TO SEE IF ANY OF THE EFIS-RELATED SYMPTOMS WERE EVIDENT. THEY WERE NOT. WE THEN NOTICED THE CABIN WAS BTWN 8500-9000 FT. IT BECAME APPARENT THAT THE CABIN WAS NOT GOING TO STOP CLBING; SO WE BEGAN TO ACCOMPLISH THE CHKLIST BY SELECTING THE ALT CONTROLLER WHICH HAD NO EFFECT. THE CABIN ALT CONTINUED TO RISE; WITH THE HORN SOUNDING AT 10000 FT CABIN ALT. CAPT (PLT MONITORING) DIRECTED A DSCNT; AND COORD WITH ATC; DECLARING AN EMER. WITH CLRNC; AND THE CABIN ALT AT APPROX 11000 FT; FO (PF) BEGAN THE EMER DSCNT PROC. WE DONNED OUR OXYGEN MASKS; AND STARTED DOWN TO 10000 FT MSL; AND BACK TOWARDS SHORE. WHILE DSNDING THROUGH FL270; THE CABIN ALT REACHED JUST OVER 14000 FT AND THE PAX EMER OXYGEN MASKS DEPLOYED AUTOMATICALLY. ONCE ESTABLISHED IN THE DSCNT; WE WERE ABLE TO USE MANUAL CTL TO CTL THE CABIN SOMEWHAT. THE CABIN ALT DIDN'T GET MUCH ABOVE 14000 FT -- WE ESTIMATE 14500 FT.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.