Narrative:

While descending to 11;000 ft our left pack automatically switched off and all airflow stopped. The right pack was deferred. The cabin started to climb at approximately 700 FPM. The captain was the pilot flying. The pilot flying stated he had the controls and the radios and the first officer ran the unpressurised flight checklist. The pilot flying asked ATC for an immediate descent to 3;000 ft. ATC replied the lowest they could give us was 3;500 ft. We accepted that clearance and immediately made a descent to 3;000 ft. During the descent the first officer finished the QRH checklist. The captain then instructed him to tell the flight attendant of the situation as our ears were definitely popping with the quick decrease in cabin pressure. The cabin met us at approximately 5;000 ft (cabin and aircraft were at 0.0 delta P). We advised her we were at a safe cabin altitude and no action would need to be taken. We would be landing in less than 5 minutes. We were operating with a single pack as the right pack was deferred. This was a previous write up on the plane; twice prior to this event within the week. The captain had actually briefed the flight attendant and first officer to the previous write-ups and stated that we needed to look out for this. When we initially took the plane 3 flights prior. We were mentally prepared for this issue as it was a previous write-earlier. Pressurization issues are serious. If this had happened at FL250 (max altitude for a single pack) we would have had only a few minutes of useful consciousness to react. This was the third write-up in a short period of time on the same issue. These maintenance issues should be corrected better and not so easily signed off as fixed.

Related reports:

Google
 

Original NASA ASRS Text

Title: CRJ200 Captain reports being dispatched with a pack inoperative then losing the second pack during descent at 11;000 FT. Flight continues to destination with the cabin unpressurized below 5;000 FT.

Narrative: While descending to 11;000 FT our left pack automatically switched off and all airflow stopped. The right pack was deferred. The cabin started to climb at approximately 700 FPM. The Captain was the pilot flying. The pilot flying stated he had the controls and the radios and the First Officer ran the unpressurised flight checklist. The pilot flying asked ATC for an immediate descent to 3;000 FT. ATC replied the lowest they could give us was 3;500 FT. We accepted that clearance and immediately made a descent to 3;000 FT. During the descent the First Officer finished the QRH Checklist. The Captain then instructed him to tell the Flight Attendant of the situation as our ears were definitely popping with the quick decrease in cabin pressure. The cabin met us at approximately 5;000 FT (Cabin and Aircraft were at 0.0 Delta P). We advised her we were at a safe cabin altitude and no action would need to be taken. We would be landing in less than 5 minutes. We were operating with a single PACK as the right pack was deferred. This was a previous write up on the plane; twice prior to this event within the week. The Captain had actually briefed the Flight Attendant and First Officer to the previous write-ups and stated that we needed to look out for this. When we initially took the plane 3 flights prior. We were mentally prepared for this issue as it was a previous write-earlier. Pressurization issues are serious. If this had happened at FL250 (Max altitude for a single PACK) we would have had only a few minutes of useful consciousness to react. This was the third write-up in a short period of time on the same issue. These maintenance issues should be corrected better and not so easily signed off as fixed.

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.