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.