Narrative:

[We had a] long day with very bad weather. We departed on our last flight; about a one hour leg; and were focused on the local thunderstorms and navigating through them safely. There was a fair amount of lightning in the area and all anti ice and deice was engaged. As we leveled off at FL330 we got a brief 'pressurization flow' light that illuminated and then went out. Cabin was at approximately 6;500 ft (normal schedule) at FL330. Due to the convective activity there were a number of power changes with the auto throttle system; and press flow light illuminated again. Captain reviewed QRH abnormal procedures and we started to monitor pressurization which started to show a very slow climb 1-300 FPM. Per QRH we asked for lower when we felt it was safe to do so after maneuvering east of thunderstorms. We descended from FL330 to FL310 to FL290 to FL270 and cabin continued to climb...as cabin altitude began to approach 7;500 ft captain advised to expedite lower in an attempt to stabilize cabin. We made sure to leave power on to supply bleed demands. As cabin altitude reached 9;500 ft captain declared an emergency with center and asked for and received 10;000. As a precaution we both donned our oxygen masks and reviewed the emergency decent/rapid depressurization checklist. We did an expedited decent (about 2;700-3;200 FPM) down through 18;000 to the level off at 10;000. Both pack flows appeared normal and the pressure differential seemed normal. There were no pressurization controller changeover or anomalies noted. After level off at 10;000 ft the cabin seemed to stabilize and the flight was continued to destination without any further abnormalities. There was a high workload in thoroughly scanning the area for storms; which came at the end of a long day and 4 legs.

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Original NASA ASRS Text

Title: MD83 First Officer reports slow loss of cabin pressurization at FL330 while operating with all wing and engine anti ice on. A slow descent is unsuccessful at stopping the cabin altitude increase; necessitating an emergency declaration and a rapid descent to 10;000 FT. Flight continues to destination.

Narrative: [We had a] long day with very bad weather. We departed on our last flight; about a one hour leg; and were focused on the local thunderstorms and navigating through them safely. There was a fair amount of lightning in the area and all anti ice and deice was engaged. As we leveled off at FL330 we got a brief 'PRESSURIZATION FLOW' light that illuminated and then went out. Cabin was at approximately 6;500 FT (normal schedule) at FL330. Due to the convective activity there were a number of power changes with the Auto Throttle System; and Press Flow light illuminated again. Captain reviewed QRH Abnormal procedures and we started to monitor pressurization which started to show a very slow climb 1-300 FPM. Per QRH we asked for lower when we felt it was safe to do so after maneuvering east of thunderstorms. We descended from FL330 to FL310 to FL290 to FL270 and cabin continued to climb...as cabin altitude began to approach 7;500 FT Captain advised to expedite lower in an attempt to stabilize cabin. We made sure to leave power on to supply bleed demands. As cabin altitude reached 9;500 FT Captain declared an emergency with Center and asked for and received 10;000. As a precaution we both donned our oxygen masks and reviewed the emergency decent/rapid depressurization checklist. We did an expedited decent (about 2;700-3;200 FPM) down through 18;000 to the level off at 10;000. Both pack flows appeared normal and the pressure differential seemed normal. There were no pressurization controller changeover or anomalies noted. After level off at 10;000 FT the cabin seemed to stabilize and the flight was continued to destination without any further abnormalities. There was a high workload in thoroughly scanning the area for storms; which came at the end of a long day and 4 legs.

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.