An A320 captain descended to 10;000 ft after the oxygen level unexpectedly decreased and was able to...

Narrative:

Crew O2 was serviced prior to departure (2nd time in a week) as it was 1170 psi. During cruise we noticed that crew O2 pressure was decreasing at what appeared to be faster than cold-soaking would account for. We contacted dispatch. During radio contact with dispatch and flight duty officer the rate of O2 pressure decrease seemed to accelerate. I immediately decided to begin descent at that point in time. After coordination with the above parties and considering ferry fuel we fortunately had on board; we determined that the safe course of action would be to continue to descend so as to arrive at 10;000 feet altitude with much greater than flight manual required oxygen quantity and continue to destination at 10;000 feet while closely monitoring fuel reserves and available alternate airports. This we did and we landed at destination with approximately 9;000 lbs or 1.5 hrs of fuel on board on a VMC day with no alternate required. We blocked in with greater than FM required O2 quantity.

Original NASA ASRS Text

Title: An A320 Captain descended to 10;000 FT after the oxygen level unexpectedly decreased and was able to continue to the destination with sufficient fuel reserves.

Narrative: Crew O2 was serviced prior to departure (2nd time in a week) as it was 1170 PSI. During cruise we noticed that crew O2 pressure was decreasing at what appeared to be faster than cold-soaking would account for. We contacted dispatch. During radio contact with dispatch and Flight Duty Officer the rate of O2 pressure decrease seemed to accelerate. I immediately decided to begin descent at that point in time. After coordination with the above parties and considering ferry fuel we fortunately had on board; we determined that the safe course of action would be to continue to descend so as to arrive at 10;000 feet altitude with much greater than Flight Manual required oxygen quantity and continue to destination at 10;000 feet while closely monitoring fuel reserves and available alternate airports. This we did and we landed at destination with approximately 9;000 lbs or 1.5 hrs of fuel on board on a VMC day with no alternate required. We blocked in with greater than FM required O2 quantity.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	973373
Time
Date	201110
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Oxygen System/Pax
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 240 Flight Crew Total 23000 Flight Crew Type 8000
Events
Anomaly	Aircraft Equipment Problem Less Severe

An A320 captain descended to 10;000 ft after the oxygen level unexpectedly decreased and was able to continue to the destination with sufficient fuel reserves.