MD80 crew executed an emergency descent when cabin pressurization was lost.

Attributes
ACN	441604
Time
Date	199907
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : lit.vortac
State Reference	AR
Altitude	msl single value : 33000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zme.artcc
Operator	common carrier : air carrier
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 : atp
ASRS Report	441604
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : declared emergency
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Loss of cabin pressurization. Level at FL330 and cabin began slow climb to above 10000 ft. Did not notice anything unusual until cabin altitude horn sounded. Cabin altitude stabilized at 10500 ft, as we ran the rapid depressurization checklist. We were unable to lower the cabin altitude and executed the explosive depressurization checklist. Declared emergency with center and after beginning our descent we were able to positively control the cabin altitude with the manual controller. I elected to level the aircraft at FL200 for fuel considerations and we were able to assess that the passenger and the cabin area were ok. During our descent, we initially brought the cabin down to 1000 ft then slowly raised it back up to 3000 ft for passenger comfort. Flight attendant #1 again reported no adverse reactions to passenger due to short exposure above 10000 ft so we continued to our destination. Coordinated emergency procedures with dispatch, bna operations and bna maintenance during descent. Also used jump seater to manually control pressurization during descent and landing phase. Terminated emergency with bna approach when below 10000 ft. Landed without further event at bna.

Original NASA ASRS Text

Title: MD80 CREW EXECUTED AN EMER DSCNT WHEN CABIN PRESSURIZATION WAS LOST.

Narrative: LOSS OF CABIN PRESSURIZATION. LEVEL AT FL330 AND CABIN BEGAN SLOW CLB TO ABOVE 10000 FT. DID NOT NOTICE ANYTHING UNUSUAL UNTIL CABIN ALT HORN SOUNDED. CABIN ALT STABILIZED AT 10500 FT, AS WE RAN THE RAPID DEPRESSURIZATION CHKLIST. WE WERE UNABLE TO LOWER THE CABIN ALT AND EXECUTED THE EXPLOSIVE DEPRESSURIZATION CHKLIST. DECLARED EMER WITH CTR AND AFTER BEGINNING OUR DSCNT WE WERE ABLE TO POSITIVELY CTL THE CABIN ALT WITH THE MANUAL CTLR. I ELECTED TO LEVEL THE ACFT AT FL200 FOR FUEL CONSIDERATIONS AND WE WERE ABLE TO ASSESS THAT THE PAX AND THE CABIN AREA WERE OK. DURING OUR DSCNT, WE INITIALLY BROUGHT THE CABIN DOWN TO 1000 FT THEN SLOWLY RAISED IT BACK UP TO 3000 FT FOR PAX COMFORT. FLT ATTENDANT #1 AGAIN RPTED NO ADVERSE REACTIONS TO PAX DUE TO SHORT EXPOSURE ABOVE 10000 FT SO WE CONTINUED TO OUR DEST. COORDINATED EMER PROCS WITH DISPATCH, BNA OPS AND BNA MAINT DURING DSCNT. ALSO USED JUMP SEATER TO MANUALLY CTL PRESSURIZATION DURING DSCNT AND LNDG PHASE. TERMINATED EMER WITH BNA APCH WHEN BELOW 10000 FT. LANDED WITHOUT FURTHER EVENT AT BNA.

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.