Cabin pressurization loss at 35000 ft.

Attributes
ACN	489748
Time
Date	200010
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zau.artcc
State Reference	IL
Altitude	msl single value : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 198 flight time total : 8900 flight time type : 2000
ASRS Report	489748
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : cab alt warning
Resolutory Action	flight crew : declared emergency
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

After leveloff at FL350 the altitude warning horn sounded, indicating the cabin altitude reached 10000 ft. We donned oxygen masks and ran the appropriate checklists as we stared descent to 10000 ft. Cabin altitude should have stopped at 5200 ft. The passenger oxygen masks deployed at 13000 ft cabin altitude. They should have deployed at 14000 ft. We leveled at 10000 ft without incident. When the altitude horn sounded at 10000 ft cabin altitude, the cabin VV1 (vertical speed) showed 1200 FPM climb. The pressure controller was changed and the next leg was flown without incident.

Original NASA ASRS Text

Title: CABIN PRESSURIZATION LOSS AT 35000 FT.

Narrative: AFTER LEVELOFF AT FL350 THE ALT WARNING HORN SOUNDED, INDICATING THE CABIN ALT REACHED 10000 FT. WE DONNED OXYGEN MASKS AND RAN THE APPROPRIATE CHKLISTS AS WE STARED DSCNT TO 10000 FT. CABIN ALT SHOULD HAVE STOPPED AT 5200 FT. THE PAX OXYGEN MASKS DEPLOYED AT 13000 FT CABIN ALT. THEY SHOULD HAVE DEPLOYED AT 14000 FT. WE LEVELED AT 10000 FT WITHOUT INCIDENT. WHEN THE ALT HORN SOUNDED AT 10000 FT CABIN ALT, THE CABIN VV1 (VERT SPD) SHOWED 1200 FPM CLB. THE PRESSURE CTLR WAS CHANGED AND THE NEXT LEG WAS FLOWN WITHOUT INCIDENT.

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.