Narrative:

We were dispatched with manual pressurization. While climbing through 10000 ft to FL230 the captain was controling the pressure according to the operations manual. At approximately 15000 ft the captain noticed the cabin climbing through 9000 ft. The captain moved the control to full closed and got clearance to level at 17000 ft. We got further clearance to descend to 10000 ft. During this time the cabin altitude climbed causing the cabin altitude warning light followed shortly by passenger oxygen deployment (with light). The captain made several appropriate PA's. The captain got the cabin pressure under control. We declared an emergency with center and diverted into ZZZ for a heavy weight landing. Our overweight for landing for 131200 pounds was normal. Supplemental information from acn 725730: we were told before takeoff that the automatic pressurization unit on the aircraft was not working and that they would have to manually adjust the pressurization during the flight. About 15 mins/17000 ft; the masks dropped. We ensured everyone was on oxygen and waited from the cockpit. The captain shortly said it was safe to go off of oxygen and that we were going to divert to ZZZ. In ZZZ we changed planes and continued onto ZZZ2. As a crew; we only experienced discomfort in our ears; and upset stomachs. No one/passenger asked for medical attention.

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Original NASA ASRS Text

Title: AN MD80 DISPATCHED WITH ONLY MANUAL PRESSURIZATION CTL; LOST PRESSURE AT 15000 FT; DECLARED AN EMER AND DIVERTED WITH OXYGEN MASKS DROPPED.

Narrative: WE WERE DISPATCHED WITH MANUAL PRESSURIZATION. WHILE CLBING THROUGH 10000 FT TO FL230 THE CAPT WAS CTLING THE PRESSURE ACCORDING TO THE OPS MANUAL. AT APPROX 15000 FT THE CAPT NOTICED THE CABIN CLBING THROUGH 9000 FT. THE CAPT MOVED THE CTL TO FULL CLOSED AND GOT CLRNC TO LEVEL AT 17000 FT. WE GOT FURTHER CLRNC TO DSND TO 10000 FT. DURING THIS TIME THE CABIN ALT CLBED CAUSING THE CABIN ALT WARNING LIGHT FOLLOWED SHORTLY BY PAX OXYGEN DEPLOYMENT (WITH LIGHT). THE CAPT MADE SEVERAL APPROPRIATE PA'S. THE CAPT GOT THE CABIN PRESSURE UNDER CTL. WE DECLARED AN EMER WITH CTR AND DIVERTED INTO ZZZ FOR A HVY WT LNDG. OUR OVERWT FOR LNDG FOR 131200 LBS WAS NORMAL. SUPPLEMENTAL INFO FROM ACN 725730: WE WERE TOLD BEFORE TKOF THAT THE AUTO PRESSURIZATION UNIT ON THE ACFT WAS NOT WORKING AND THAT THEY WOULD HAVE TO MANUALLY ADJUST THE PRESSURIZATION DURING THE FLT. ABOUT 15 MINS/17000 FT; THE MASKS DROPPED. WE ENSURED EVERYONE WAS ON OXYGEN AND WAITED FROM THE COCKPIT. THE CAPT SHORTLY SAID IT WAS SAFE TO GO OFF OF OXYGEN AND THAT WE WERE GOING TO DIVERT TO ZZZ. IN ZZZ WE CHANGED PLANES AND CONTINUED ONTO ZZZ2. AS A CREW; WE ONLY EXPERIENCED DISCOMFORT IN OUR EARS; AND UPSET STOMACHS. NO ONE/PAX ASKED FOR MEDICAL ATTN.

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.