A boeing 747-400 flight crew detected a crew oxygen leak and diverted to ord.

Attributes
ACN	443121
Time
Date	199907
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : 41yxl
State Reference	MB
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : czwg.artcc
Operator	common carrier : air carrier
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute airway : nca22.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 160 flight time total : 22900 flight time type : 679
ASRS Report	443121
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : diverted to alternate
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Nwbound on J-63 approaching syr at FL310, captain noticed crew oxygen at 1340 psi. Noted time and pressure and observed system depleting at 10 psi every 4-12 mins. Contacted company maintenance controller and dispatch and discussed problem, continued on course and monitored oxygen system leak. At approximately XA45Z with 1200 psi, diverted to ord rather than continue into remote navigation area and a pacific crossing with depleting oxygen. Dumped approximately 50,000 pounds of fuel south of qt at FL330 to arrive ord below maximum structural landing weight. Approach and landing normal.

Original NASA ASRS Text

Title: A BOEING 747-400 FLC DETECTED A CREW OXYGEN LEAK AND DIVERTED TO ORD.

Narrative: NWBOUND ON J-63 APCHING SYR AT FL310, CAPT NOTICED CREW OXYGEN AT 1340 PSI. NOTED TIME AND PRESSURE AND OBSERVED SYS DEPLETING AT 10 PSI EVERY 4-12 MINS. CONTACTED COMPANY MAINT CTLR AND DISPATCH AND DISCUSSED PROB, CONTINUED ON COURSE AND MONITORED OXYGEN SYS LEAK. AT APPROX XA45Z WITH 1200 PSI, DIVERTED TO ORD RATHER THAN CONTINUE INTO REMOTE NAV AREA AND A PACIFIC XING WITH DEPLETING OXYGEN. DUMPED APPROX 50,000 LBS OF FUEL S OF QT AT FL330 TO ARRIVE ORD BELOW MAX STRUCTURAL LNDG WT. APCH AND LNDG NORMAL.

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.