Climbing cabin altitude mandates aircraft to perform an emergency descent.

Attributes
ACN	305128
Time
Date	199505
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : dbl
State Reference	CO
Altitude	msl bound lower : 31000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude descent other other
Route In Use	departure other departure sid : sid
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
ASRS Report	305128
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 950 flight time total : 12000 flight time type : 50
ASRS Report	305544
Events
Anomaly	aircraft equipment problem : critical non adherence : published procedure other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency flight crew : exited adverse environment flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During climb out on ROCKI2 departure at FL310 cabin altitude warning horn sounded. Crew noted the cabin altitude was 11000 ft and climbing. Crew initiated emergency descent. While accomplishing the immediate action items we noted that the right airconditioning pack switch was off. Crew continued the descent to FL180 and got cabin under control and below 9000 ft. We contacted maintenance and determined that there was no history of pressurization problems. With cabin stabilized at 6000 ft and descending we started a gradual climb to FL310 with the cabin stable at 4100 ft. We continued uneventfully to las. The cause of the problem was due to the right airconditioning pack being off. I believe this was due to the so being new to the airplane. He either did not turn the pack on after all engines were started or accidentally turned it off.

Original NASA ASRS Text

Title: CLBING CABIN ALT MANDATES ACFT TO PERFORM AN EMER DSCNT.

Narrative: DURING CLBOUT ON ROCKI2 DEP AT FL310 CABIN ALT WARNING HORN SOUNDED. CREW NOTED THE CABIN ALT WAS 11000 FT AND CLBING. CREW INITIATED EMER DSCNT. WHILE ACCOMPLISHING THE IMMEDIATE ACTION ITEMS WE NOTED THAT THE R AIRCONDITIONING PACK SWITCH WAS OFF. CREW CONTINUED THE DSCNT TO FL180 AND GOT CABIN UNDER CTL AND BELOW 9000 FT. WE CONTACTED MAINT AND DETERMINED THAT THERE WAS NO HISTORY OF PRESSURIZATION PROBS. WITH CABIN STABILIZED AT 6000 FT AND DSNDING WE STARTED A GRADUAL CLB TO FL310 WITH THE CABIN STABLE AT 4100 FT. WE CONTINUED UNEVENTFULLY TO LAS. THE CAUSE OF THE PROB WAS DUE TO THE R AIRCONDITIONING PACK BEING OFF. I BELIEVE THIS WAS DUE TO THE SO BEING NEW TO THE AIRPLANE. HE EITHER DID NOT TURN THE PACK ON AFTER ALL ENGS WERE STARTED OR ACCIDENTALLY TURNED IT OFF.

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.