MD83 crew experiences a pressurization problem. Emergency is declared and descent is made.

Attributes
ACN	626157
Time
Date	200408
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : irw.vortac
State Reference	OK
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	MD-83
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
ASRS Report	626157
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Pressurization system malfunctioned. An emergency was declared, and an emergency descent was accomplished. Callback conversation with reporter revealed the following information: the crew noted the failure initially by the change in pressure effecting their ears then noted the cabin rate of climb was pegged. The aircraft was in cruise at FL310. Cabin altitude was maintained below 10000 ft. It was determined that 1 pack had overheated and shut down leaving the remaining one unable to hold pressurization at high altitude. Pressurization was adequate at lower altitude so flight was continued to destination.

Original NASA ASRS Text

Title: MD83 CREW EXPERIENCES A PRESSURIZATION PROB. EMER IS DECLARED AND DSCNT IS MADE.

Narrative: PRESSURIZATION SYS MALFUNCTIONED. AN EMER WAS DECLARED, AND AN EMER DSCNT WAS ACCOMPLISHED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CREW NOTED THE FAILURE INITIALLY BY THE CHANGE IN PRESSURE EFFECTING THEIR EARS THEN NOTED THE CABIN RATE OF CLB WAS PEGGED. THE ACFT WAS IN CRUISE AT FL310. CABIN ALT WAS MAINTAINED BELOW 10000 FT. IT WAS DETERMINED THAT 1 PACK HAD OVERHEATED AND SHUT DOWN LEAVING THE REMAINING ONE UNABLE TO HOLD PRESSURIZATION AT HIGH ALT. PRESSURIZATION WAS ADEQUATE AT LOWER ALT SO FLT WAS CONTINUED TO DEST.

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.