B737-300 captain reported loss of cabin pressure at FL370. Emergency was declared; the flight descen...

Narrative:

We were enroute at fl 370. It was night/IMC with a significant area of thunderstorms along our route. The F/as were seated and the seatbelt sign was on due to potential turbulence. The first officer was PF; and I was pm. We were in process of coordinating/accomplishing weather deviations when the cabin altitude warning horn sounded. We immediately accomplished and verified the appropriate memory items; checked the cabin altitude (it was above 10;000'); and requested an immediate descent from ATC. A cursory check indicated that the air conditioning/pressurization systems were properly configured and no other warning lights were illuminated. We accomplished the cabin altitude warning/abnormal pressurization checklist; and since the cabin altitude was still uncontrollable (now at 12;000'); declared an emergency and requested descent to the highest of 10;000' or minimum vectoring altitude. I contacted the F/as; informed them of our pressurization situation; and advised them that the psu oxygen masks might deploy. I asked them if there was any abnormalities in the cabin and was told outside of a squeaky door seal everything was normal. During our descent; we encountered constant moderate turbulence due to the convective activity in the area. We leveled off at 12;000'; at which point the pressurization was controllable. We were in constant moderate turbulence due to some low level cumulus clouds. We chose to climb back up to 16;000'; which was on top and the ride was smooth (the pressurization was stable). We agreed to proceed to [destination] at 16;000' since the pressurization was now controllable. There was no evidence of any structural abnormality; [we] had sufficient fuel; and were past the convective activity. I contacted dispatch and informed them of the situation and our plan to continue to [destination]. I made a PA giving our passengers an update on our pressurization situation; apologized for the bumpy ride; and updated ETA/weather. Outside of some minor sinus distress; all of the passengers were fine and no one needed any assistance.

Original NASA ASRS Text

Title: B737-300 Captain reported loss of cabin pressure at FL370. Emergency was declared; the flight descended to 12;000 ft where pressurization control was regained.

Narrative: We were enroute at FL 370. It was night/IMC with a significant area of thunderstorms along our route. The F/As were seated and the seatbelt sign was on due to potential turbulence. The First Officer was PF; and I was PM. We were in process of coordinating/accomplishing weather deviations when the Cabin Altitude Warning horn sounded. We immediately accomplished and verified the appropriate memory items; checked the cabin altitude (it was above 10;000'); and requested an immediate descent from ATC. A cursory check indicated that the air conditioning/pressurization systems were properly configured and no other warning lights were illuminated. We accomplished the Cabin Altitude Warning/Abnormal Pressurization Checklist; and since the cabin altitude was still uncontrollable (now at 12;000'); declared an emergency and requested descent to the highest of 10;000' or minimum vectoring altitude. I contacted the F/As; informed them of our pressurization situation; and advised them that the PSU oxygen masks might deploy. I asked them if there was any abnormalities in the cabin and was told outside of a squeaky door seal everything was normal. During our descent; we encountered constant moderate turbulence due to the convective activity in the area. We leveled off at 12;000'; at which point the pressurization was controllable. We were in constant moderate turbulence due to some low level cumulus clouds. We chose to climb back up to 16;000'; which was on top and the ride was smooth (the pressurization was stable). We agreed to proceed to [destination] at 16;000' since the pressurization was now controllable. There was no evidence of any structural abnormality; [we] had sufficient fuel; and were past the convective activity. I contacted Dispatch and informed them of the situation and our plan to continue to [destination]. I made a PA giving our passengers an update on our pressurization situation; apologized for the bumpy ride; and updated ETA/weather. Outside of some minor sinus distress; all of the passengers were fine and no one needed any assistance.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1014493
Time
Date	201206
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	B737-300
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pressurization System
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 134 Flight Crew Type 15000
Events
Anomaly	Aircraft Equipment Problem Critical Inflight Event / Encounter Weather / Turbulence

B737-300 captain reported loss of cabin pressure at FL370. Emergency was declared; the flight descended to 12;000 ft where pressurization control was regained.