Narrative:

Pressurization system was placarded in accordance with MEL 21-23a. Secondary pressurization system was expected to pressurize the aircraft normally. On departure; the aircraft did not pressurize at all. We declared an emergency and diverted landing overweight.

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Original NASA ASRS Text

Title: An MD80 Captain reported being dispatched with one pressurization system on MEL and having the second fail after takeoff. An emergency is declared and the flight diverts for an overweight landing.

Narrative: Pressurization system was placarded in accordance with MEL 21-23a. Secondary pressurization system was expected to pressurize the aircraft normally. On departure; the aircraft did not pressurize at all. We declared an emergency and diverted landing overweight.

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.