Narrative:

Dispatched with one of two channels of pressurization system inop. Began normal descent. When passing though approximately FL300; EICAS message observed 'presn automatic fail'. Cabin altitude was at 8;000 ft and climbing. Donned oxygen masks. Declared emergency with center. Began emergency descent. 'Cabin press hi' EICAS message appeared. The aircraft oversped on descent. Communication was very difficult. The first officer ran the QRH. ATC eventually cleared us to 6;000 ft and before we got to 6;000 ft the pressurization returned to normal. Max cabin altitude approximately 14;000 ft. The passenger oxygen masks did not drop. Once at 6;000 ft things were normal. Made an uneventful landing in at our destination. The event occurred because the only remaining pressurization channel malfunctioned. I suggest a review of the MEL procedure that enables dispatch with one channel of the pressurization system inop.

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Original NASA ASRS Text

Title: Dispatched with one channel of the auto-pressurization control system deferred; an ERJ190 flight crew suffered the loss of pressurization when the other channel failed.

Narrative: Dispatched with one of two channels of pressurization system inop. Began normal descent. When passing though approximately FL300; EICAS message observed 'PRESN AUTO FAIL'. Cabin altitude was at 8;000 FT and climbing. Donned oxygen masks. Declared emergency with Center. Began emergency descent. 'Cabin Press Hi' EICAS message appeared. The Aircraft oversped on descent. Communication was very difficult. The First Officer ran the QRH. ATC eventually cleared us to 6;000 FT and before we got to 6;000 FT the pressurization returned to normal. Max cabin altitude approximately 14;000 FT. The passenger oxygen masks did not drop. Once at 6;000 FT things were normal. Made an uneventful landing in at our destination. The event occurred because the only remaining pressurization channel malfunctioned. I suggest a review of the MEL procedure that enables dispatch with one channel of the pressurization system inop.

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.