Air carrier large transport unable control cabin altitude rate of climb makes emergency descent.

Attributes
ACN	100910
Time
Date	198812
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : jot
State Reference	IL
Altitude	msl bound lower : 10000 msl bound upper : 30000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	arrival other enroute airway : zau
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 80 flight time total : 15600 flight time type : 8000
ASRS Report	100910
Person 2
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	faa : investigated
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Upon beginning descent, passing 32500, throttles idle, air conditioner in automatic, altitude horn sounded. Cabin pressurization was passing 10000. Reached 10500' declared an emergency and began descent to 10000'. Manual AC and dc used initially. Altitude horn cut out button did not silence the horn. Standby and automatic modes used in latter part of descent and worked normally. Landed mke without incident.

Original NASA ASRS Text

Title: ACR LGT UNABLE CONTROL CABIN ALT RATE OF CLIMB MAKES EMERGENCY DESCENT.

Narrative: UPON BEGINNING DSCNT, PASSING 32500, THROTTLES IDLE, AIR CONDITIONER IN AUTO, ALT HORN SOUNDED. CABIN PRESSURIZATION WAS PASSING 10000. REACHED 10500' DECLARED AN EMER AND BEGAN DSCNT TO 10000'. MANUAL AC AND DC USED INITIALLY. ALT HORN CUT OUT BUTTON DID NOT SILENCE THE HORN. STANDBY AND AUTO MODES USED IN LATTER PART OF DSCNT AND WORKED NORMALLY. LANDED MKE WITHOUT INCIDENT.

Data retrieved from NASA's ASRS site as of August 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.