B737-400 suffers loss of pressurization. Returns to departure airport.

Attributes
ACN	749308
Time
Date	200708
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz.artcc tracon : clt.tracon
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
ASRS Report	749308
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : cabin alt warning horn
Resolutory Action	flight crew : declared emergency other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Maintenance problem or unrelated failure after maintenance. Cabin altitude exceeded 10000 ft. Returned to ZZZ. Aircraft had come from hangar and returned to hangar after our return. Cabin altitude warning horn. Declared emergency. Given ATC clearance to descend to 10000 ft and to return to ZZZ. Canceled emergency when below 10000 ft.

Original NASA ASRS Text

Title: B737-400 SUFFERS LOSS OF PRESSURIZATION. RETURNS TO DEP ARPT.

Narrative: MAINT PROB OR UNRELATED FAILURE AFTER MAINT. CABIN ALT EXCEEDED 10000 FT. RETURNED TO ZZZ. ACFT HAD COME FROM HANGAR AND RETURNED TO HANGAR AFTER OUR RETURN. CABIN ALT WARNING HORN. DECLARED EMER. GIVEN ATC CLRNC TO DSND TO 10000 FT AND TO RETURN TO ZZZ. CANCELED EMER WHEN BELOW 10000 FT.

Data retrieved from NASA's ASRS site as of January 2009 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.