Narrative:

After reaching cruise altitude of FL340 the pressurization warning horn sounded. We ran the qrc and asked for a lower altitude. We descended normally to FL250 and determined pressurization was actually holding. We contacted dispatch and maintenance and determined we actually had not lost pressure so we continued to destination and landed normally. Callback conversation with reporter revealed the following information: after the cabin altitude warning horn was canceled by the flight crew it was determined that cabin altitude was normal and a precautionary descent to FL250 was requested. A log book entry was made but maintenance could find no reason for the horn to sound.

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Original NASA ASRS Text

Title: B737 FLT CREW EXPERIENCES FALSE CABIN ALTITUDE WARNING HORN AT FL340 AND DESCENDS TO FL250 AS A PRECAUTION AND CONTINUES TO DESTINATION.

Narrative: AFTER REACHING CRUISE ALT OF FL340 THE PRESSURIZATION WARNING HORN SOUNDED. WE RAN THE QRC AND ASKED FOR A LOWER ALT. WE DSNDED NORMALLY TO FL250 AND DETERMINED PRESSURIZATION WAS ACTUALLY HOLDING. WE CONTACTED DISPATCH AND MAINT AND DETERMINED WE ACTUALLY HAD NOT LOST PRESSURE SO WE CONTINUED TO DEST AND LANDED NORMALLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: AFTER THE CABIN ALTITUDE WARNING HORN WAS CANCELED BY THE FLT CREW IT WAS DETERMINED THAT CABIN ALTITUDE WAS NORMAL AND A PRECAUTIONARY DESCENT TO FL250 WAS REQUESTED. A LOG BOOK ENTRY WAS MADE BUT MAINTENANCE COULD FIND NO REASON FOR THE HORN TO SOUND.

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.