Air carrier medium large transport unable to control cabin altitude executed emergency descent.

Attributes
ACN	88641
Time
Date	198806
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : sie
State Reference	NJ
Altitude	msl bound lower : 10000 msl bound upper : 15000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute airway : zdc
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 3900 flight time type : 350
ASRS Report	88641
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	88905
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : declared emergency
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

While level at 15000' MSL after a descent from 17000' we heard the altitude alert horn go off. We put on our O2 masks and ran the emergency checklist. We could not control the climbing cabin and initiated an emergency descent from 15000' for 10000'. I had been flying at the time, but the captain took control of the aircraft for the descent. Because of radio congestion I was unable to notify washington center that we were descending until we were passing 14000'. We were then given immediate clearance to 10000'. We coordinated for direct to philadelphia.

Original NASA ASRS Text

Title: ACR MLG UNABLE TO CONTROL CABIN ALT EXECUTED EMERGENCY DESCENT.

Narrative: WHILE LEVEL AT 15000' MSL AFTER A DSCNT FROM 17000' WE HEARD THE ALT ALERT HORN GO OFF. WE PUT ON OUR O2 MASKS AND RAN THE EMER CHKLIST. WE COULD NOT CTL THE CLBING CABIN AND INITIATED AN EMER DSCNT FROM 15000' FOR 10000'. I HAD BEEN FLYING AT THE TIME, BUT THE CAPT TOOK CTL OF THE ACFT FOR THE DSCNT. BECAUSE OF RADIO CONGESTION I WAS UNABLE TO NOTIFY WASHINGTON CENTER THAT WE WERE DSNDING UNTIL WE WERE PASSING 14000'. WE WERE THEN GIVEN IMMEDIATE CLRNC TO 10000'. WE COORDINATED FOR DIRECT TO PHILADELPHIA.

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.