Narrative:

At FL370 (while in cruise flight) the cabin altitude horn sounded. We observed the cabin altitude to be 10000 ft. After a brief scan of the air conditioning and pressurization panel and the door lights (in which nothing appeared to be abnormal, except for the cabin altitude being excessive), we donned our oxygen masks, established crew communications, turned on the seat belt sign and requested a lower altitude from ATC. ATC initially gave us FL330, but we requested lower. He then told us to turn right 30 degrees (which we did immediately). We then asked for FL240, and very shortly thereafter asked for 14000 ft (to prevent the cabin masks from falling). ATC told us to descend to 13000 ft. Ultimately we only descended to 16000 ft. Between the initiation of the descent and the radio calls, we proceeded to run the expanded loss of pressurization checklist. The captain was the PF. I was the pilot monitoring. After completing the first 3 items on the checklist, we realized we had regained control of the cabin pressure. Once we were assured that the pressure was stable, we elected to continue to our destination (lga). We monitored the cabin pressure closely for the remainder of the flight. The pressurization system was written up upon our arrival into lga. Maintenance performed numerous checks and no problems were found.

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Original NASA ASRS Text

Title: A B737-500 IN CRUISE AT FL370 HAD THE CABIN ALT HORN SOUND AND MADE A RAPID DSCNT TO 16000 FT WHERE PRESSURIZATION CTL WAS REGAINED. FLT CONTINUED TO DEST WITH NO PROBS. MAINT RPTED NO PRESSURIZATION PROBS FOUND ON SYS CHKS.

Narrative: AT FL370 (WHILE IN CRUISE FLT) THE CABIN ALT HORN SOUNDED. WE OBSERVED THE CABIN ALT TO BE 10000 FT. AFTER A BRIEF SCAN OF THE AIR CONDITIONING AND PRESSURIZATION PANEL AND THE DOOR LIGHTS (IN WHICH NOTHING APPEARED TO BE ABNORMAL, EXCEPT FOR THE CABIN ALT BEING EXCESSIVE), WE DONNED OUR OXYGEN MASKS, ESTABLISHED CREW COMS, TURNED ON THE SEAT BELT SIGN AND REQUESTED A LOWER ALT FROM ATC. ATC INITIALLY GAVE US FL330, BUT WE REQUESTED LOWER. HE THEN TOLD US TO TURN R 30 DEGS (WHICH WE DID IMMEDIATELY). WE THEN ASKED FOR FL240, AND VERY SHORTLY THEREAFTER ASKED FOR 14000 FT (TO PREVENT THE CABIN MASKS FROM FALLING). ATC TOLD US TO DSND TO 13000 FT. ULTIMATELY WE ONLY DSNDED TO 16000 FT. BTWN THE INITIATION OF THE DSCNT AND THE RADIO CALLS, WE PROCEEDED TO RUN THE EXPANDED LOSS OF PRESSURIZATION CHKLIST. THE CAPT WAS THE PF. I WAS THE PLT MONITORING. AFTER COMPLETING THE FIRST 3 ITEMS ON THE CHKLIST, WE REALIZED WE HAD REGAINED CTL OF THE CABIN PRESSURE. ONCE WE WERE ASSURED THAT THE PRESSURE WAS STABLE, WE ELECTED TO CONTINUE TO OUR DEST (LGA). WE MONITORED THE CABIN PRESSURE CLOSELY FOR THE REMAINDER OF THE FLT. THE PRESSURIZATION SYS WAS WRITTEN UP UPON OUR ARR INTO LGA. MAINT PERFORMED NUMEROUS CHKS AND NO PROBS WERE FOUND.

Data retrieved from NASA's ASRS site as of July 2007 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.