Date: 201506
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Pressurization Control System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Situational Awareness; Troubleshooting; Workload
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Enroute cruise at FL320. Flow light started to flicker then became steady as we witnessed the cabin rate indication start to climb with corresponding cabin altitude rise.  Cabin altitude started off on schedule and was indicating around 7000.  Pilots took O2 masks down to easily access them and tested them again. Donned O2 masks. Decent was coordinated with ATC; as QRH was consulted and completed. Descents were initiated; coordinated with ATC to FL300; FL260; FL240; then finally 10000. Throughout initial descent; we had speed brakes extended and power high as to permit the greatest inflow of pressurization. Both auto 1 and auto 2 pressure controllers were attempted with same result. Outflow valve indicator was showing full closed; and I additionally overrode the auto control of the outflow valve and assured it was in fact fully closed. Once it became apparent that a high power speed brake extended descent was not sufficient as to allow the cabin to pressurize in such a way that we would be able to keep up or manage the rate of cabin climb to an acceptable level and coordinated 10000 feet with ATC. At this point we initiated a speed brake extended power at idle max decent to 10000 as to 'beat' the cabins rate of climb down to an acceptable cruising altitude. FA were contacted and briefed on the condition. No brace no evacuation no special handling was anticipated from the FA perspective; and a time frame was given until a safe landing at our destination. Once we reached 10000; our emergency situation was no longer present; so we [notified] ATC. PAX were advised over PA of the initial decent; as normal; with no indication of the emergency. From the PAX perspective; it was a normal time for this PA and there was no abnormal decent nor aircraft attitude from their perspective. The max cabin altitude reached was 9200 feet at the end of our decent to 10000. Attempted to contact dispatch/maintenance control via AIRINC 4x but was unsuccessful. We called in range to the station and gave them a heads up about our situation and briefed them to contact maintenance control/dispatch to give them the info. Normal decent approach and landing was accomplished without further incident.




Synopsis: The flight crew reported that they were unable to control the cabin pressurization. Several lower altitudes were requested from ATC until the aircraft leveled at 10;000 feet. The cabin altitude never exceeded 9;200 feet and a normal approach and landing was accomplished.