Narrative:

On preflight of DC9-32 aircraft, noted crew oxygen bottle was near empty. Reported to captain, who left cockpit to call maintenance control/dispatch. Approximately 25 mins later, captain reboards and says we were redispatched to fly to iad at 10000 ft, and to call clearance delivery for new clearance. Obtaining the low altitude clearance, I got out charts and verified victor airways route. Captain asked for before start checklist, and normal start, taxi, and takeoff accomplished. While at cruise, I felt uneasy about the fact we were flying with a nearly empty crew oxygen tank and checked the MEL book. Sure enough, we were legal to dispatch at 10000 ft for an inoperative passenger oxygen bottle. Lesson learned: when you feel uneasy about something, and captain is pushing to get clrncs, do checklists, etc, stop and check the MEL operations requirements before leaving the gate. Always doublechk the dispatcher's release for legality! In this case, the dispatcher led the captain to believe he was legal to fly. My assumption as a first officer that the captain had obtained a legal solution to the problem was in error. In the future, I will check all MEL'ed items before continuing a flight. If I had voiced my concerns earlier, the problem would have been discovered before leaving the gate. I believe crossed communications between the captain and maintenance/dispatcher led to confusion over which oxygen system was affected.

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Original NASA ASRS Text

Title: DC9-32 ACFT WAS DISPATCHED WITH LOW OXYGEN SUPPLY. LEGAL TO DISPATCH WITH LOW PAX OXYGEN IF FLT IS AT 10000 FT, BUT NOT LEGAL IF CREW OXYGEN IS LOW.

Narrative: ON PREFLT OF DC9-32 ACFT, NOTED CREW OXYGEN BOTTLE WAS NEAR EMPTY. RPTED TO CAPT, WHO LEFT COCKPIT TO CALL MAINT CTL/DISPATCH. APPROX 25 MINS LATER, CAPT REBOARDS AND SAYS WE WERE REDISPATCHED TO FLY TO IAD AT 10000 FT, AND TO CALL CLRNC DELIVERY FOR NEW CLRNC. OBTAINING THE LOW ALT CLRNC, I GOT OUT CHARTS AND VERIFIED VICTOR AIRWAYS RTE. CAPT ASKED FOR BEFORE START CHKLIST, AND NORMAL START, TAXI, AND TKOF ACCOMPLISHED. WHILE AT CRUISE, I FELT UNEASY ABOUT THE FACT WE WERE FLYING WITH A NEARLY EMPTY CREW OXYGEN TANK AND CHKED THE MEL BOOK. SURE ENOUGH, WE WERE LEGAL TO DISPATCH AT 10000 FT FOR AN INOP PAX OXYGEN BOTTLE. LESSON LEARNED: WHEN YOU FEEL UNEASY ABOUT SOMETHING, AND CAPT IS PUSHING TO GET CLRNCS, DO CHKLISTS, ETC, STOP AND CHK THE MEL OPS REQUIREMENTS BEFORE LEAVING THE GATE. ALWAYS DOUBLECHK THE DISPATCHER'S RELEASE FOR LEGALITY! IN THIS CASE, THE DISPATCHER LED THE CAPT TO BELIEVE HE WAS LEGAL TO FLY. MY ASSUMPTION AS A FO THAT THE CAPT HAD OBTAINED A LEGAL SOLUTION TO THE PROB WAS IN ERROR. IN THE FUTURE, I WILL CHK ALL MEL'ED ITEMS BEFORE CONTINUING A FLT. IF I HAD VOICED MY CONCERNS EARLIER, THE PROB WOULD HAVE BEEN DISCOVERED BEFORE LEAVING THE GATE. I BELIEVE CROSSED COMS BTWN THE CAPT AND MAINT/DISPATCHER LED TO CONFUSION OVER WHICH OXYGEN SYS WAS AFFECTED.

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.