Narrative:

Cruising at FL290 with a crossing of FL250 at xyz fix. I pointed out cabin altitude was in a constant descent (500 FPM) with cabin pressure increasing. The captain noted it and told me to start descent to FL250. On the way down to FL250 the captain puts the pressure controller in manual mode and tries to correct the problem manually. Shortly after the cabin controller display turn amber with the cabin altitude descending at 1000+ FPM. The captain then calls for an emergency descent and we don our oxygen masks. I am PF so I initiate the emergency descent to 10000 ft. The captain declares an emergency to ATC. During the descent the captain tells me to deploy passenger oxygen masks. The autoplt is flying so I reach up and deploy the masks. After we level at 10000 ft; the captain asks the flight attendants if everything and everyone is alright and everyone is. We land and the rest is uneventful.

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Original NASA ASRS Text

Title: AN EMB170 FLT CREW EXPERIENCES A MALFUNCTIONING CABIN PRESSURE CONTROLLER. THEY DECLARE AN EMER AND EXECUTE AN EMER DSCNT.

Narrative: CRUISING AT FL290 WITH A XING OF FL250 AT XYZ FIX. I POINTED OUT CABIN ALT WAS IN A CONSTANT DSCNT (500 FPM) WITH CABIN PRESSURE INCREASING. THE CAPT NOTED IT AND TOLD ME TO START DSCNT TO FL250. ON THE WAY DOWN TO FL250 THE CAPT PUTS THE PRESSURE CONTROLLER IN MANUAL MODE AND TRIES TO CORRECT THE PROB MANUALLY. SHORTLY AFTER THE CABIN CONTROLLER DISPLAY TURN AMBER WITH THE CABIN ALT DSNDING AT 1000+ FPM. THE CAPT THEN CALLS FOR AN EMER DSCNT AND WE DON OUR OXYGEN MASKS. I AM PF SO I INITIATE THE EMER DSCNT TO 10000 FT. THE CAPT DECLARES AN EMER TO ATC. DURING THE DSCNT THE CAPT TELLS ME TO DEPLOY PAX OXYGEN MASKS. THE AUTOPLT IS FLYING SO I REACH UP AND DEPLOY THE MASKS. AFTER WE LEVEL AT 10000 FT; THE CAPT ASKS THE FLT ATTENDANTS IF EVERYTHING AND EVERYONE IS ALRIGHT AND EVERYONE IS. WE LAND AND THE REST IS UNEVENTFUL.

Data retrieved from NASA's ASRS site as of January 2009 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.