Flight crew of an medium large transport descended off of assigned cruise altitude due to a loss of ...

Attributes
ACN	310980
Time
Date	199507
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : gve
State Reference	VA
Altitude	msl bound lower : 31000 msl bound upper : 35000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
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 descent other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 170 flight time total : 14000 flight time type : 10000
ASRS Report	310980
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

A cabin pressure warning light came on during cruise, and we confirmed the cabin pressure was at 9600 ft and rising. We began an immediate descent, telling center we wanted to go to 10000 ft. Having a couple seconds to look at the indications, it became obvious that just the one, primary pressurization system had failed. We made a second call to center, asking them for 31000 ft instead, until we could get our cabin pressure back. Center approved this, we leveled at 31000 ft, we recovered cabin pressure with the secondary pressurization system, and then later climbed back to 35000 ft. I felt uncomfortable descending as quickly as we did, and in retrospect I would have rather stayed at 35000 ft for a few extra seconds, until center gave us a clearance to descend.

Original NASA ASRS Text

Title: FLC OF AN MLG DSNDED OFF OF ASSIGNED CRUISE ALT DUE TO A LOSS OF CABIN PRESSURE.

Narrative: A CABIN PRESSURE WARNING LIGHT CAME ON DURING CRUISE, AND WE CONFIRMED THE CABIN PRESSURE WAS AT 9600 FT AND RISING. WE BEGAN AN IMMEDIATE DSCNT, TELLING CTR WE WANTED TO GO TO 10000 FT. HAVING A COUPLE SECONDS TO LOOK AT THE INDICATIONS, IT BECAME OBVIOUS THAT JUST THE ONE, PRIMARY PRESSURIZATION SYS HAD FAILED. WE MADE A SECOND CALL TO CTR, ASKING THEM FOR 31000 FT INSTEAD, UNTIL WE COULD GET OUR CABIN PRESSURE BACK. CTR APPROVED THIS, WE LEVELED AT 31000 FT, WE RECOVERED CABIN PRESSURE WITH THE SECONDARY PRESSURIZATION SYS, AND THEN LATER CLBED BACK TO 35000 FT. I FELT UNCOMFORTABLE DSNDING AS QUICKLY AS WE DID, AND IN RETROSPECT I WOULD HAVE RATHER STAYED AT 35000 FT FOR A FEW EXTRA SECONDS, UNTIL CTR GAVE US A CLRNC TO DSND.

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.

Flight crew of an medium large transport descended off of assigned cruise altitude due to a loss of cabin pressure.