Narrative:

Departed ord-buf, climbing through FL330-FL370 over south michigan, checked pressurization during climb at about FL250-FL270 -- all ok. At about FL330 south of dtw, cabin altitude light illuminated. Up to this point, cabin pressurization operations normal, and no pressurization changes felt. Stopped aircraft climb at approximately FL330 (cabin altitude at about 10000 ft and climbing slowing at about 700 FPM). Attempted to arrest climb reference operations manual checklist. In process of following checklist, noted cabin altitude lever in autoplt (but outflow valve indicator at full open position). No other lights were illuminated, ie, flow/xfer lockout on standby on light. Called ZOB, declared emergency (emergency descent) requested landing dtw and dfw equipment. Completed checklist and emergency descent checklist. Passenger oxygen masks deployed as prescribed. Requested ATC notify company. Did standard descent checks and before landing checklist. Briefed approach runway 3L dtw, radar vectors to runway 3L too high. Did l-hand 360 degree turn for descent onto localizer at about OM. Resumed approach. Normal landing. Made PA to passenger and flight attendants to stay seated and taxied to gate. Crash fire rescue equipment followed us to ramp. No flight attendant or passenger injuries. Callback conversation with reporter revealed the following information: the reporter stated the airplane was an md super 80. The reporter said the loss of cabin pressure caused by the autopressure controller.

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Original NASA ASRS Text

Title: AN MD80 IN CLB AT FL330 DECLARED AN EMER AND DIVERTED DUE TO LOSS OF CABIN PRESSURE CAUSED BY A FAILED AUTOPRESSURE CONTROLLER.

Narrative: DEPARTED ORD-BUF, CLBING THROUGH FL330-FL370 OVER SOUTH MICHIGAN, CHKED PRESSURIZATION DURING CLB AT ABOUT FL250-FL270 -- ALL OK. AT ABOUT FL330 S OF DTW, CABIN ALT LIGHT ILLUMINATED. UP TO THIS POINT, CABIN PRESSURIZATION OPS NORMAL, AND NO PRESSURIZATION CHANGES FELT. STOPPED ACFT CLB AT APPROX FL330 (CABIN ALT AT ABOUT 10000 FT AND CLBING SLOWING AT ABOUT 700 FPM). ATTEMPTED TO ARREST CLB REF OPS MANUAL CHKLIST. IN PROCESS OF FOLLOWING CHKLIST, NOTED CABIN ALT LEVER IN AUTOPLT (BUT OUTFLOW VALVE INDICATOR AT FULL OPEN POS). NO OTHER LIGHTS WERE ILLUMINATED, IE, FLOW/XFER LOCKOUT ON STANDBY ON LIGHT. CALLED ZOB, DECLARED EMER (EMER DSCNT) REQUESTED LNDG DTW AND DFW EQUIPMENT. COMPLETED CHKLIST AND EMER DSCNT CHKLIST. PAX OXYGEN MASKS DEPLOYED AS PRESCRIBED. REQUESTED ATC NOTIFY COMPANY. DID STANDARD DSCNT CHKS AND BEFORE LNDG CHKLIST. BRIEFED APCH RWY 3L DTW, RADAR VECTORS TO RWY 3L TOO HIGH. DID L-HAND 360 DEG TURN FOR DSCNT ONTO LOC AT ABOUT OM. RESUMED APCH. NORMAL LNDG. MADE PA TO PAX AND FLT ATTENDANTS TO STAY SEATED AND TAXIED TO GATE. CFR FOLLOWED US TO RAMP. NO FLT ATTENDANT OR PAX INJURIES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE AIRPLANE WAS AN MD SUPER 80. THE RPTR SAID THE LOSS OF CABIN PRESSURE CAUSED BY THE AUTOPRESSURE CONTROLLER.

Data retrieved from NASA's ASRS site as of July 2007 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.