B737 CREW HAS CABIN ALTITUDE WARNING HORN SOUND JUST AFTER LEVELOFF AT FL360. CREW IS ABLE TO CONTROL CABIN IN STANDBY MODE AND CONTINUE FLIGHT.

Narrative

JUST AFTER LEVELOFF THE CABIN ALT WARNING HORN WENT OFF. I PUT ON MY MASK; IDENTED THAT THE CABIN ALT WAS AT 10500 FT AND THE DIFFERENTIAL WAS AT 6.8. THE CABIN PRESSURE CHANGE INDICATOR SHOWED A CLB OF APPROX 500 FPM. THE PRESSURIZATION PANEL WAS CORRECTLY CONFIGURED IN THE AUTO MODE. I BEGAN DSNDING THE ACFT AND NOTIFIED ATC OF OUR DSCNT. AS THE ACFT BEGAN THE DSCNT I DIRECTED THE FO TO RUN THE LOSS OF PRESSURIZATION CHKLIST. THE FIRST STEP WAS TO SELECT STANDBY ON THE PRESSURIZATION PANEL. THE CABIN CLB/DSCNT INDICATOR IMMEDIATELY WENT FROM A 500 FPM CLB TO A 500 FPM DSCNT. I ASKED ATC FOR A LEVELOFF AT FL320. WE LEVELED OFF; I SENT MAINT A MESSAGE ABOUT AUTO PRESSURIZATION FAILURE. AT MAINT REQUEST I CONTACTED MAINT CTL VERBALLY OVER RADIO AND GAVE THEM THE DETAILS. THEY TOLD ME THE PLANE HAD A HISTORY OF THE SAME FAILURE 30 DAYS PREVIOUS. AFTER A FEW MINS IN STANDBY THE ACFT CABIN ALT WAS APPROX 6000 FT AS CALLED FOR BY THE PRESSURIZATION PANEL. I NOTIFIED THE FLT ATTENDANTS OF THE SITUATION AND ASKED IF THEY NOTICED ANYTHING IN THE CABIN. THEY SAID ALL APPEARED NORMAL. WE CONTINUED THE FLT AT FL320 IN THE STANDBY MODE WITH NO FURTHER EVENTS.