A B737-300 in cruise at FL290 declared an emergency and descended due to loss of cabin pressurizatio...

Attributes
ACN	530745
Time
Date	200111
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 29000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time last 90 days : 230 flight time total : 16500 flight time type : 2804
ASRS Report	530745
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : cabin pressure indicator other flight crewa other flight crewb
Resolutory Action	flight crew : declared emergency
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Level stabilized cruise at FL290 after previously cruising at FL370. Altitude warning horn sounded and cabin altitude indicator was showing 10500 ft and increasing. No pressure change had been noticed by either crew member. Analog pressure system was set to proper altitudes and no other cockpit indications for reason of loss of cabin pressure. Both crew members donned oxygen masks and ran checklist. Captain noted cabin altitude indication still climbing towards 14000 ft and elected to deploy passenger oxygen masks and called for immediate (emergency) descent. Emergency was declared solely for the purpose of ensuring traffic separation in the descent. Once level at 10000 ft MSL, cabin stabilized and captain contacted dispatch who advised to continue on. Approach and landing were normal. Not one complaint or injury report was received by any crew member on deplaning every person complemented the flight and especially our cabin crew. As of writing of this report, the cause of the depressurized indication is still unknown to the crew.!

Original NASA ASRS Text

Title: A B737-300 IN CRUISE AT FL290 DECLARED AN EMER AND DSNDED DUE TO LOSS OF CABIN PRESSURIZATION. CAUSE UNKNOWN.

Narrative: LEVEL STABILIZED CRUISE AT FL290 AFTER PREVIOUSLY CRUISING AT FL370. ALT WARNING HORN SOUNDED AND CABIN ALT INDICATOR WAS SHOWING 10500 FT AND INCREASING. NO PRESSURE CHANGE HAD BEEN NOTICED BY EITHER CREW MEMBER. ANALOG PRESSURE SYS WAS SET TO PROPER ALTS AND NO OTHER COCKPIT INDICATIONS FOR REASON OF LOSS OF CABIN PRESSURE. BOTH CREW MEMBERS DONNED OXYGEN MASKS AND RAN CHKLIST. CAPT NOTED CABIN ALT INDICATION STILL CLBING TOWARDS 14000 FT AND ELECTED TO DEPLOY PAX OXYGEN MASKS AND CALLED FOR IMMEDIATE (EMER) DSCNT. EMER WAS DECLARED SOLELY FOR THE PURPOSE OF ENSURING TFC SEPARATION IN THE DSCNT. ONCE LEVEL AT 10000 FT MSL, CABIN STABILIZED AND CAPT CONTACTED DISPATCH WHO ADVISED TO CONTINUE ON. APCH AND LNDG WERE NORMAL. NOT ONE COMPLAINT OR INJURY RPT WAS RECEIVED BY ANY CREW MEMBER ON DEPLANING EVERY PERSON COMPLEMENTED THE FLT AND ESPECIALLY OUR CABIN CREW. AS OF WRITING OF THIS RPT, THE CAUSE OF THE DEPRESSURIZED INDICATION IS STILL UNKNOWN TO THE CREW.!

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.

A B737-300 in cruise at FL290 declared an emergency and descended due to loss of cabin pressurization. Cause unknown.