Narrative:

At FL320 the cabin altitude warning sounded. Check of the cabin altitude indicator confirmed cabin above 10000 ft. The corrective actions taken were in accordance with air carrier QRH. Had trouble initially in communications; could not tell if we could control the cabin; emergency descent initiated. Emergency terminated at 10000 ft and in agreement with dispatch; diverted to ZZZ; normal landing. On landing in ZZZ with maintenance on board; determined pressurization controller was faulty.callback conversation with reporter revealed the following information: the reporter stated that it took him about 5 seconds to recognize the horn's cause adding that for some reason he looked at the airspeed indicator. He does now know why his initial thought was about an overspd. Once the cabin altitude was identified as the horn's cause; the correct procedures were initiated quickly. The reporter believed the horn recognition took so long because the 'high dive' rapid depressurization maneuver is no longer performed in the simulator.

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Original NASA ASRS Text

Title: A B737-400 FLT CREW EXPERIENCED A DEPRESSURIZED CABIN DUE TO A PRESSURE CTLR FAILURE. AN EMER DSCNT WAS FOLLOWED BY A DIVERSION TO A NEARBY ARPT.

Narrative: AT FL320 THE CABIN ALT WARNING SOUNDED. CHK OF THE CABIN ALT INDICATOR CONFIRMED CABIN ABOVE 10000 FT. THE CORRECTIVE ACTIONS TAKEN WERE IN ACCORDANCE WITH ACR QRH. HAD TROUBLE INITIALLY IN COMMUNICATIONS; COULD NOT TELL IF WE COULD CTL THE CABIN; EMER DSCNT INITIATED. EMER TERMINATED AT 10000 FT AND IN AGREEMENT WITH DISPATCH; DIVERTED TO ZZZ; NORMAL LNDG. ON LNDG IN ZZZ WITH MAINT ON BOARD; DETERMINED PRESSURIZATION CTLR WAS FAULTY.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT IT TOOK HIM ABOUT 5 SECONDS TO RECOGNIZE THE HORN'S CAUSE ADDING THAT FOR SOME REASON HE LOOKED AT THE AIRSPD INDICATOR. HE DOES NOW KNOW WHY HIS INITIAL THOUGHT WAS ABOUT AN OVERSPD. ONCE THE CABIN ALT WAS IDENTIFIED AS THE HORN'S CAUSE; THE CORRECT PROCS WERE INITIATED QUICKLY. THE RPTR BELIEVED THE HORN RECOGNITION TOOK SO LONG BECAUSE THE 'HIGH DIVE' RAPID DEPRESSURIZATION MANEUVER IS NO LONGER PERFORMED IN THE SIMULATOR.

Data retrieved from NASA's ASRS site as of January 2009 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.