Pressurization warning at FL330 in a DC9-30.

Attributes
ACN	472755
Time
Date	200005
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : pit.airport
State Reference	PA
Altitude	msl single value : 33000
Environment
Flight Conditions	IMC
Weather Elements	Ice
Light	Night
Aircraft 1
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : commercial pilot : flight engineer pilot : instrument pilot : atp
Experience	flight time last 90 days : 140 flight time total : 10700 flight time type : 5000
ASRS Report	472755
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : cab alt warning other flight crewa
Resolutory Action	controller : separated traffic flight crew : declared emergency flight crew : overcame equipment problem
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Cruise FL330, in icing conditions, deviating northeast of course due to WX. We reviewed a 'cabin pressurization' warning. The cabin was approximately 10000 ft and climbing approximately 400 FPM. We donned oxygen masks, began checklist, and began descent as cabin climbed through 11000 ft. One plane had to be moved off course for our descent. At some point in the checklist, in our descent, pressurization in manual mode, cabin began to descend. It was controled manually throughout flight to landing at pittsburgh. Though we (crew) could not prevent a recurrence, we did find communication difficult and use of oxygen masks, intercom, trying to talk to ATC was a handful. At night made it that much harder to read/accomplish checklist items. Turning cockpit lights on sooner would have helped. New radios, being put into DC9 aircraft (though not yet on this plane) would also have helped as we could've used a hot microphone intercom.

Original NASA ASRS Text

Title: PRESSURIZATION WARNING AT FL330 IN A DC9-30.

Narrative: CRUISE FL330, IN ICING CONDITIONS, DEVIATING NE OF COURSE DUE TO WX. WE REVIEWED A 'CABIN PRESSURIZATION' WARNING. THE CABIN WAS APPROX 10000 FT AND CLBING APPROX 400 FPM. WE DONNED OXYGEN MASKS, BEGAN CHKLIST, AND BEGAN DSCNT AS CABIN CLBED THROUGH 11000 FT. ONE PLANE HAD TO BE MOVED OFF COURSE FOR OUR DSCNT. AT SOME POINT IN THE CHKLIST, IN OUR DSCNT, PRESSURIZATION IN MANUAL MODE, CABIN BEGAN TO DSND. IT WAS CTLED MANUALLY THROUGHOUT FLT TO LNDG AT PITTSBURGH. THOUGH WE (CREW) COULD NOT PREVENT A RECURRENCE, WE DID FIND COM DIFFICULT AND USE OF OXYGEN MASKS, INTERCOM, TRYING TO TALK TO ATC WAS A HANDFUL. AT NIGHT MADE IT THAT MUCH HARDER TO READ/ACCOMPLISH CHKLIST ITEMS. TURNING COCKPIT LIGHTS ON SOONER WOULD HAVE HELPED. NEW RADIOS, BEING PUT INTO DC9 ACFT (THOUGH NOT YET ON THIS PLANE) WOULD ALSO HAVE HELPED AS WE COULD'VE USED A HOT MIKE INTERCOM.

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.