Narrative:

Shortly after leveling off at FL350 for our planned cruise altitude; we heard the cabin altitude warning horn without any other warning light indications. Both pilots immediately donned our oxygen masks and established communications with each other. We noticed the cabin pressure gauge read 10;000 ft; the cabin rate indicator was climbing; both packs were in auto and both engine bleeds were on; and the outflow valve gauge was reading full closed. With the cabin altitude at 10;000 ft and climbing; the captain (pilot not flying) declared an emergency with ATC and asked for a descent. ATC initially gave us FL330 then shortly after the first officer (pilot flying) started the emergency descent; they gave us FL240 then down to 10;000 ft. The first officer (pilot flying) continued the emergency descent on autopilot while the captain (pilot not flying) read through the cabin altitude warning/abnormal pressurization checklist and emergency descent checklist. After reading the checklist; the captain (pilot not flying) informed the flight attendants to take their seats; and advised them of our pressurization problem; emergency descent; and the possibility of the masks deploying. During our emergency descent; we went to manual/AC on the pressure controller to ensure the outflow value was full closed. This had no effect at controlling the cabin pressure. Passing between FL200 to FL180; the cabin altitude reached 14;000 ft and the oxygen light on the overhead panel illuminated. We confirmed with the flight attendants that the masks dropped and everyone was on oxygen. The cabin altitude reached 15;000 ft and then descended with the aircraft altitude until it stabilized at 10;000 ft. A diversion was considered; but fuel; weather; and no medical requirements allowed us to agree with dispatch for a continued flight to destination.

Related reports:

Google
 

Original NASA ASRS Text

Title: B737-300 flight crew experiences a cabin altitude warning horn shortly after leveling off at FL350. An emergency is declared; oxygen masks are donned; and the flight descends to 10;000 FT. During the descent the cabin altitude exceeds 14;000 FT and the passenger oxygen masks drop. The crew is able to continue to destination at 10;000 FT.

Narrative: Shortly after leveling off at FL350 for our planned cruise altitude; we heard the Cabin Altitude Warning horn without any other warning light indications. Both pilots immediately donned our oxygen masks and established communications with each other. We noticed the Cabin Pressure gauge read 10;000 FT; the cabin rate indicator was climbing; both packs were in auto and both engine bleeds were on; and the Outflow Valve gauge was reading full closed. With the cabin altitude at 10;000 FT and climbing; the Captain (pilot not flying) declared an emergency with ATC and asked for a descent. ATC initially gave us FL330 then shortly after the First Officer (pilot flying) started the emergency descent; they gave us FL240 then down to 10;000 FT. The First Officer (pilot flying) continued the emergency descent on autopilot while the Captain (pilot not flying) read through the Cabin Altitude Warning/Abnormal Pressurization Checklist and Emergency Descent Checklist. After reading the checklist; the Captain (pilot not flying) informed the flight attendants to take their seats; and advised them of our pressurization problem; emergency descent; and the possibility of the masks deploying. During our emergency descent; we went to manual/AC on the pressure controller to ensure the outflow value was full closed. This had no effect at controlling the cabin pressure. Passing between FL200 to FL180; the cabin altitude reached 14;000 FT and the oxygen light on the overhead panel illuminated. We confirmed with the flight attendants that the masks dropped and everyone was on oxygen. The cabin altitude reached 15;000 FT and then descended with the aircraft altitude until it stabilized at 10;000 FT. A diversion was considered; but fuel; weather; and no medical requirements allowed us to agree with Dispatch for a continued flight to destination.

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.