Narrative:

Crew was en route to mci at FL350 ft deviating around thunderstorm activity. Approximately 45 mins from landing at mci, the crew observed a red master warning light illuminate, along with a corresponding red cabin pressure annunciator light. The crew then checked the cabin pressure controller and noted an amber flow light and that the cabin was at 10000 ft and slowly climbing. The crew also noted that the blue standby on and xfer lockout lights were illuminated. The crew then performed the memory items for a cabin pressure loss, requested a descent from ATC for operational purposes, and consulted the QRH for additional guidance. ATC complied with our request for a descent, gave us a turn, and started us down. At this point, the #1 flight attendant informed us that the masks had 'dropped' in the cabin. When time permitted, I made a PA to the passenger explaining the situation and instructing them to remove their oxygen masks. At no time did the cabin altitude exceed 12000 ft. The utilization of CRM techniques during this situation aided the crew in achieving the successful outcome. Supplemental information from acn 587586: as the cabin was climbing slowly approximately 500 FPM, we did a rapid descent, but not an emergency descent. As we descended, we regained pressurization and leveled off at 10000 ft. Cabin altitude reached a maximum of 12000 ft. Flight continued to mci at 10000 ft.

Related reports:

Google
 

Original NASA ASRS Text

Title: PAX OXYGEN MASKS ARE DEPLOYED AS THE CABIN PRESSURE OF A DC9-30 RISES TO 12000 FT AFTER A PARTIAL LOSS OF PRESSURE AT FL350 ON FREQ WITH ZKC, KC.

Narrative: CREW WAS ENRTE TO MCI AT FL350 FT DEVIATING AROUND TSTM ACTIVITY. APPROX 45 MINS FROM LNDG AT MCI, THE CREW OBSERVED A RED MASTER WARNING LIGHT ILLUMINATE, ALONG WITH A CORRESPONDING RED CABIN PRESSURE ANNUNCIATOR LIGHT. THE CREW THEN CHKED THE CABIN PRESSURE CONTROLLER AND NOTED AN AMBER FLOW LIGHT AND THAT THE CABIN WAS AT 10000 FT AND SLOWLY CLBING. THE CREW ALSO NOTED THAT THE BLUE STANDBY ON AND XFER LOCKOUT LIGHTS WERE ILLUMINATED. THE CREW THEN PERFORMED THE MEMORY ITEMS FOR A CABIN PRESSURE LOSS, REQUESTED A DSCNT FROM ATC FOR OPERATIONAL PURPOSES, AND CONSULTED THE QRH FOR ADDITIONAL GUIDANCE. ATC COMPLIED WITH OUR REQUEST FOR A DSCNT, GAVE US A TURN, AND STARTED US DOWN. AT THIS POINT, THE #1 FLT ATTENDANT INFORMED US THAT THE MASKS HAD 'DROPPED' IN THE CABIN. WHEN TIME PERMITTED, I MADE A PA TO THE PAX EXPLAINING THE SIT AND INSTRUCTING THEM TO REMOVE THEIR OXYGEN MASKS. AT NO TIME DID THE CABIN ALT EXCEED 12000 FT. THE UTILIZATION OF CRM TECHNIQUES DURING THIS SIT AIDED THE CREW IN ACHIEVING THE SUCCESSFUL OUTCOME. SUPPLEMENTAL INFO FROM ACN 587586: AS THE CABIN WAS CLBING SLOWLY APPROX 500 FPM, WE DID A RAPID DSCNT, BUT NOT AN EMER DSCNT. AS WE DSNDED, WE REGAINED PRESSURIZATION AND LEVELED OFF AT 10000 FT. CABIN ALT REACHED A MAX OF 12000 FT. FLT CONTINUED TO MCI AT 10000 FT.

Data retrieved from NASA's ASRS site as of July 2007 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.