An md-83 was unable to maintain pressurization at altitude. The flight crew declared an emergency; d...

Narrative:

At FL330 we activated tail de-ice. Approximately two minutes later; we observed the cabin altitude climbing at about 500 FPM. [We] obtained normal descent to FL250. Cabin altitude control valve was fully closed. Left pack showed no pressure. Right pack had normal pressure. Shutting off both wing anti ice and left pack had no effect on maintaining pressurization. The pressurization flow light never illuminated. We declared an emergency; descended rapidly to 10;000 ft and landed uneventfully at our destination. The maximum cabin altitude reached was approximately 12;000 ft.

Original NASA ASRS Text

Title: An MD-83 was unable to maintain pressurization at altitude. The flight crew declared an emergency; descended to a safe altitude and landed uneventfully at their destination.

Narrative: At FL330 we activated tail de-ice. Approximately two minutes later; we observed the cabin altitude climbing at about 500 FPM. [We] obtained normal descent to FL250. Cabin altitude control valve was fully closed. Left pack showed no pressure. Right pack had normal pressure. Shutting off both wing anti ice and left pack had no effect on maintaining pressurization. The pressurization flow light never illuminated. We declared an emergency; descended rapidly to 10;000 FT and landed uneventfully at our destination. The maximum cabin altitude reached was approximately 12;000 FT.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	941854
Time
Date	201104
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	MD-83
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Air Conditioning and Pressurization Pack
Person 1
Function	First Officer
Events
Anomaly	Aircraft Equipment Problem Critical

An md-83 was unable to maintain pressurization at altitude. The flight crew declared an emergency; descended to a safe altitude and landed uneventfully at their destination.