Medium large transport at cruise has cabin altitude alert activate.

Attributes
ACN	309121
Time
Date	199507
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mco
State Reference	FL
Altitude	msl bound lower : 37000 msl bound upper : 37000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 210 flight time total : 16500 flight time type : 8700
ASRS Report	309121
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 170 flight time total : 9000 flight time type : 5000
ASRS Report	309261
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency none taken : unable other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

Aircraft had just leveled off at FL370. ZJX cleared us direct taylor. Cabin altitude alerter went off at cabin altitude of 10000 ft. No door lights were illuminated. Packs and bleeds ok. Outflow valve indicated open approximately 1/4 from full close with a cabin climb of 850-950 FPM and cabin at 11000 ft. An emergency descent was initiated, checklists accomplished, and a diversion to mco was made. No known injuries. Aircraft was repaired and we continued to phl.

Original NASA ASRS Text

Title: MLG AT CRUISE HAS CABIN ALT ALERT ACTIVATE.

Narrative: ACFT HAD JUST LEVELED OFF AT FL370. ZJX CLRED US DIRECT TAYLOR. CABIN ALT ALERTER WENT OFF AT CABIN ALT OF 10000 FT. NO DOOR LIGHTS WERE ILLUMINATED. PACKS AND BLEEDS OK. OUTFLOW VALVE INDICATED OPEN APPROX 1/4 FROM FULL CLOSE WITH A CABIN CLB OF 850-950 FPM AND CABIN AT 11000 FT. AN EMER DSCNT WAS INITIATED, CHKLISTS ACCOMPLISHED, AND A DIVERSION TO MCO WAS MADE. NO KNOWN INJURIES. ACFT WAS REPAIRED AND WE CONTINUED TO PHL.

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.