Narrative:

I was the pilot flying. We originally leveled off at FL350 due to weight. We decided we would remain at FL350 for the remainder of the flight due to a smooth ride and ride reports initially at FL370 were light chop. ATC asked if we could climb to FL370 for traffic. We told them that we would be able and they started to vector us. While on an easterly heading; ATC cleared us to FL370. FL370 was selected in the MCP; altitude window; and the CDU. After doing this; a climb was started to FL370. Passing through FL360; the altitude warning horn started to sound. Masks were donned and we established communications with each other. I silenced the horn and looked up. The cabin was at an altitude of 11;000 ft with a differential of 6.0. I do not remember looking at the cabin rate of climb. I called for the cabin altitude warning/abnormal pressurization checklist. While the first officer was starting the QRH procedures; I selected packs to high and initially leveled off the aircraft. ATC was told that we were having a pressurization issue and that we would need to level off and obtain a possible descent clearance. At this time; the cabin had started a descent of approximately 200 FPM. We left the power up on the aircraft; started a 700 FPM descent with the packs in high; and received an initial clearance to FL250. The cabin continued a 200 FPM descent. The packs; bleeds; and pressurization controller were all normal. I contacted the flight attendants and told them what was happening and that the cabin was returning to normal. I asked if they could tell any difference in the pressurization and asked if there was any air leaks noted around the door seals or anywhere else in the aircraft. They reported back that everything was normal and that they could not tell that anything had happened. We had our oxygen masks on for approximately five minutes until the cabin was once again below 10;000 ft. After level off at FL250; the cabin stabilized at 5;000 ft and 4.0 differential. I contacted dispatch and maintenance control and relayed the information back to them. Dispatch wanted us to continue the flight to our destination. The remainder of the flight was normal with the exception that the cabin was slightly higher than normal. I do recite the ad for the cabin horn for the first flight during the day or during a crew change. Even doing this daily; my first response to the horn going off was; 'why is the takeoff warning horn going off?' it took 1 to 1.5 seconds to realize that it was now the cabin horn. In my opinion; this should be fixed and have a separate horn or verbal annunciation; not just a light that is being installed on some ng aircraft. Once a day while at work; I read a page out of the QRH. By doing this; I knew that buried in the left side of the QRH procedure is a note that you may put the pack in high and keep the power up. Yes; I think that it is common sense; but I also believe that this should be part of the procedure on the right side of the checklist. I will say that this was a non-event because of our training and the help of our QRH.

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Original NASA ASRS Text

Title: A B737-300 cabin altitude warning horn sounded at FL360 as the aircraft climbed. The crew completed the QRH and descended to FL250 where the cabin stabilized at 4;000 FT. There was momentary takeoff warning horn confusion.

Narrative: I was the pilot flying. We originally leveled off at FL350 due to weight. We decided we would remain at FL350 for the remainder of the flight due to a smooth ride and ride reports initially at FL370 were light chop. ATC asked if we could climb to FL370 for traffic. We told them that we would be able and they started to vector us. While on an easterly heading; ATC cleared us to FL370. FL370 was selected in the MCP; altitude window; and the CDU. After doing this; a climb was started to FL370. Passing through FL360; the altitude warning horn started to sound. Masks were donned and we established communications with each other. I silenced the horn and looked up. The cabin was at an altitude of 11;000 FT with a differential of 6.0. I do not remember looking at the cabin rate of climb. I called for the cabin altitude warning/abnormal pressurization checklist. While the First Officer was starting the QRH procedures; I selected PACKs to high and initially leveled off the aircraft. ATC was told that we were having a pressurization issue and that we would need to level off and obtain a possible descent clearance. At this time; the cabin had started a descent of approximately 200 FPM. We left the power up on the aircraft; started a 700 FPM descent with the packs in high; and received an initial clearance to FL250. The cabin continued a 200 FPM descent. The PACKs; bleeds; and pressurization controller were all normal. I contacted the flight attendants and told them what was happening and that the cabin was returning to normal. I asked if they could tell any difference in the pressurization and asked if there was any air leaks noted around the door seals or anywhere else in the aircraft. They reported back that everything was normal and that they could not tell that anything had happened. We had our oxygen masks on for approximately five minutes until the cabin was once again below 10;000 FT. After level off at FL250; the cabin stabilized at 5;000 FT and 4.0 differential. I contacted Dispatch and Maintenance Control and relayed the information back to them. Dispatch wanted us to continue the flight to our destination. The remainder of the flight was normal with the exception that the cabin was slightly higher than normal. I do recite the AD for the Cabin Horn for the first flight during the day or during a Crew change. Even doing this daily; my first response to the horn going off was; 'Why is the takeoff warning horn going off?' It took 1 to 1.5 seconds to realize that it was now the cabin horn. In my opinion; this should be fixed and have a separate horn or verbal annunciation; not just a light that is being installed on some NG aircraft. Once a day while at work; I read a page out of the QRH. By doing this; I knew that buried in the left side of the QRH procedure is a note that you may put the PACK in HIGH and keep the power up. Yes; I think that it is common sense; but I also believe that this should be part of the procedure on the right side of the checklist. I will say that this was a non-event because of our training and the help of our QRH.

Data retrieved from NASA's ASRS site as of April 2012 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.