Narrative:

While descending to FL300 ATC issued a clearance to FL240. Nearing FL300; we noticed that the pressurization page had popped up on the systems display. The systems page showed the cabin altitude pulsating green and indicating a cabin altitude of 8;900 feet. The cabin vertical speed was showing a climb of about 500 fpm. There were no other system faults indicated. We decided to expedite our descent in case the situation deteriorated further. We asked for and received an immediate clearance to 12;000 feet initially and then 10;000 feet shortly thereafter from center. As we descended; the cabin altitude continued to drift higher at 700-800 fpm. When the indicated cabin altitude reached 10;000 feet we put our oxygen masks on and established communications. This was followed shortly thereafter by the master warning and ECAM cabin attendant pr excess cabin attendant altitude around FL250. We completed the ECAM and also did the emergency descent QRH. Since we already had our clearance to 10;000 feet and were quite busy at the time; we did not declare an emergency or squawk 7700. We still had no indications of any other systems anomalies or faults at this point. The pressurization page showed the outflow valve to be in a normal position and cpc SYS1 showed green. I checked the bleed system display page and everything indicated normal outputs on it. Nevertheless; the indicated cabin altitude continued to drift higher as we descended. Passing below FL200; I selected the pressurization control to manual and tried moving the outflow valve towards closed. The outflow valve was near the first tick mark on the displayed range of movement. As I moved the outflow valve towards the closed position; the cabin vertical speed spiked downward to a 2;000 fpm descent rate and the display turned amber. Also; the safety valve indication became amber and the safety valve opened. I then moved the outflow valve back towards its original position near the first tick mark and the safety valve closed. At this point; I selected the auto mode again which brought cpc SYS2 on line with a green indication. Cpc SYS2 did not appear to react any differently than cpc SYS1 did. The indicated cabin altitude peaked at about 14;500 feet which caused the passenger oxygen masks in the cabin to automatically drop. Upon reaching 10;000 feet we were able to brief the flight attendants on our status as well as make a PA to the passengers. We were then able to continue with a normal approach and landing.

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Original NASA ASRS Text

Title: A320 flight crew experiences an apparent pressurization anomaly after commencing descent and receives clearance for an expedited descent to 10;000 feet. The cabin pressure indication eventually rises to 14;500 feet where the passenger oxygen masks are automatically deployed. Attempts to control the cabin pressure manually are not successful with the safety valve opening at one point; indicating a cabin over pressure.

Narrative: While descending to FL300 ATC issued a clearance to FL240. Nearing FL300; we noticed that the pressurization page had popped up on the systems display. The systems page showed the cabin altitude pulsating green and indicating a cabin altitude of 8;900 feet. The cabin vertical speed was showing a climb of about 500 fpm. There were no other system faults indicated. We decided to expedite our descent in case the situation deteriorated further. We asked for and received an immediate clearance to 12;000 feet initially and then 10;000 feet shortly thereafter from Center. As we descended; the cabin altitude continued to drift higher at 700-800 fpm. When the indicated cabin altitude reached 10;000 feet we put our oxygen masks on and established communications. This was followed shortly thereafter by the master warning and ECAM CAB PR EXCESS CAB ALT around FL250. We completed the ECAM and also did the Emergency Descent QRH. Since we already had our clearance to 10;000 feet and were quite busy at the time; we did not declare an emergency or squawk 7700. We still had no indications of any other systems anomalies or faults at this point. The pressurization page showed the outflow valve to be in a normal position and CPC SYS1 showed green. I checked the bleed system display page and everything indicated normal outputs on it. Nevertheless; the indicated cabin altitude continued to drift higher as we descended. Passing below FL200; I selected the pressurization control to manual and tried moving the outflow valve towards closed. The outflow valve was near the first tick mark on the displayed range of movement. As I moved the outflow valve towards the closed position; the cabin vertical speed spiked downward to a 2;000 fpm descent rate and the display turned amber. Also; the safety valve indication became amber and the safety valve opened. I then moved the outflow valve back towards its original position near the first tick mark and the safety valve closed. At this point; I selected the auto mode again which brought CPC SYS2 on line with a green indication. CPC SYS2 did not appear to react any differently than CPC SYS1 did. The indicated cabin altitude peaked at about 14;500 feet which caused the passenger oxygen masks in the cabin to automatically drop. Upon reaching 10;000 feet we were able to brief the flight attendants on our status as well as make a PA to the passengers. We were then able to continue with a normal approach and landing.

Data retrieved from NASA's ASRS site as of July 2013 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.