Large transport loss of cabin pressure during high altitude cruise resulting in an emergency descent...

Attributes
ACN	309425
Time
Date	199507
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : buf
State Reference	NY
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 180 flight time total : 21000
ASRS Report	309425
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency flight crew : overcame equipment problem flight crew : exited adverse environment
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

While in cruise at FL330, cabin altitude horn and cabin altitude warning light came on. The cabin had climbed rapidly to 13000 ft, and we declared an emergency and initiated an emergency descent -- center cleared us to 10000 ft as we accomplished the loss of pressure checklist. The out flow valve was open. So manual pressurization was selected and the outflow valve slowly started to close. When we leveled at 10000 ft the cabin pressure stabilized at 9000 ft and was controled in the manual mode until landing. Other than the rapid descent no other priority handling was necessary and we continued on to boston with no other problems.

Original NASA ASRS Text

Title: LGT LOSS OF CABIN PRESSURE DURING HIGH ALT CRUISE RESULTING IN AN EMER DSCNT.

Narrative: WHILE IN CRUISE AT FL330, CABIN ALT HORN AND CABIN ALT WARNING LIGHT CAME ON. THE CABIN HAD CLBED RAPIDLY TO 13000 FT, AND WE DECLARED AN EMER AND INITIATED AN EMER DSCNT -- CTR CLRED US TO 10000 FT AS WE ACCOMPLISHED THE LOSS OF PRESSURE CHKLIST. THE OUT FLOW VALVE WAS OPEN. SO MANUAL PRESSURIZATION WAS SELECTED AND THE OUTFLOW VALVE SLOWLY STARTED TO CLOSE. WHEN WE LEVELED AT 10000 FT THE CABIN PRESSURE STABILIZED AT 9000 FT AND WAS CTLED IN THE MANUAL MODE UNTIL LNDG. OTHER THAN THE RAPID DSCNT NO OTHER PRIORITY HANDLING WAS NECESSARY AND WE CONTINUED ON TO BOSTON WITH NO OTHER PROBS.

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.