Narrative:

I flew a B737-200 after a maintenance check. It was an early morning departure and we were both feeling the effects of waking up early. I got up in the middle of my preflight flow to get more coffee and distracted myself from my usual careful check of the oxygen mask. What are the chances that maintenance and the crew would miss a deactivated oxygen system on the same day? Incredibly, we did! Also disturbing was my not seeing low indications on the oxygen gauges. Indications that assuredly were evident and missed by me on our 7 leg day! My habit is to point to many gauges as I look and therefore was surprised that I failed to catch a problem on this day. Factors: daylight savings time -- didn't get enough sleep. Supplemental information from acn 579174: event occurred on the first day of a 3-DAY pairing. It was a 7 leg B737-200 day with a XA30 central report. The night prior, maintenance had replaced one of the hydraulic pumps on the aircraft. During this procedure, they deactivated both the passenger and crew oxygen system. We went through what we thought was a normal preflight and on-time push. After turning on the 'a' system pumps, we still had a low pressure light in the engine driven pump. We taxied back to the gate and let maintenance re-check the hydraulic system. They determined that the system had air in the line and, by activating the control surfaces several times they were able to purge the air from the lines. We pushed about 30 mins late and were on our way. Somehow, during our preflight duties, we failed to properly check the oxygen system. I set the mask up to fit me and turned the system on and went to 100% and emergency and thought I had flow. I do not remember checking the overhead gauges and cannot remember doing any of the rest of the check. I may have been interrupted in my flow, but can't say for sure. We flew the rest of the day and failed to recognize any problems. We played catch-up all morning and I do not believe I checked the oxygen again. We gave the airplane up and the new pilots noticed that there was no flow on the masks. Crew oxygen gauge read 200 and passenger gauge 300. I believed that fatigue was a contributing factor on my performance early in the morning. But my poor performance during the preflight, and subsequent legs, was due mostly to complacency. I just failed to do what I was supposed to do. I made no conscious decision to omit this item, but time and again, I failed to check the oxygen. The lessons I have learned are how important every check can be and to never allow yourself to skip or omit any items. The checks we perform on a routine basis are anything but routine. I will also treat an aircraft coming out of maintenance with much more caution and double-check each item.

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Original NASA ASRS Text

Title: B737-200 CREW DID NOT DETECT THAT CREW AND PAX OXYGEN WERE NOT TURNED ON AFTER A MAINT CHK.

Narrative: I FLEW A B737-200 AFTER A MAINT CHK. IT WAS AN EARLY MORNING DEP AND WE WERE BOTH FEELING THE EFFECTS OF WAKING UP EARLY. I GOT UP IN THE MIDDLE OF MY PREFLT FLOW TO GET MORE COFFEE AND DISTRACTED MYSELF FROM MY USUAL CAREFUL CHK OF THE OXYGEN MASK. WHAT ARE THE CHANCES THAT MAINT AND THE CREW WOULD MISS A DEACTIVATED OXYGEN SYS ON THE SAME DAY? INCREDIBLY, WE DID! ALSO DISTURBING WAS MY NOT SEEING LOW INDICATIONS ON THE OXYGEN GAUGES. INDICATIONS THAT ASSUREDLY WERE EVIDENT AND MISSED BY ME ON OUR 7 LEG DAY! MY HABIT IS TO POINT TO MANY GAUGES AS I LOOK AND THEREFORE WAS SURPRISED THAT I FAILED TO CATCH A PROB ON THIS DAY. FACTORS: DAYLIGHT SAVINGS TIME -- DIDN'T GET ENOUGH SLEEP. SUPPLEMENTAL INFO FROM ACN 579174: EVENT OCCURRED ON THE FIRST DAY OF A 3-DAY PAIRING. IT WAS A 7 LEG B737-200 DAY WITH A XA30 CENTRAL RPT. THE NIGHT PRIOR, MAINT HAD REPLACED ONE OF THE HYD PUMPS ON THE ACFT. DURING THIS PROC, THEY DEACTIVATED BOTH THE PAX AND CREW OXYGEN SYS. WE WENT THROUGH WHAT WE THOUGHT WAS A NORMAL PREFLT AND ON-TIME PUSH. AFTER TURNING ON THE 'A' SYS PUMPS, WE STILL HAD A LOW PRESSURE LIGHT IN THE ENG DRIVEN PUMP. WE TAXIED BACK TO THE GATE AND LET MAINT RE-CHK THE HYD SYS. THEY DETERMINED THAT THE SYS HAD AIR IN THE LINE AND, BY ACTIVATING THE CTL SURFACES SEVERAL TIMES THEY WERE ABLE TO PURGE THE AIR FROM THE LINES. WE PUSHED ABOUT 30 MINS LATE AND WERE ON OUR WAY. SOMEHOW, DURING OUR PREFLT DUTIES, WE FAILED TO PROPERLY CHK THE OXYGEN SYS. I SET THE MASK UP TO FIT ME AND TURNED THE SYS ON AND WENT TO 100% AND EMER AND THOUGHT I HAD FLOW. I DO NOT REMEMBER CHKING THE OVERHEAD GAUGES AND CANNOT REMEMBER DOING ANY OF THE REST OF THE CHK. I MAY HAVE BEEN INTERRUPTED IN MY FLOW, BUT CAN'T SAY FOR SURE. WE FLEW THE REST OF THE DAY AND FAILED TO RECOGNIZE ANY PROBS. WE PLAYED CATCH-UP ALL MORNING AND I DO NOT BELIEVE I CHKED THE OXYGEN AGAIN. WE GAVE THE AIRPLANE UP AND THE NEW PLTS NOTICED THAT THERE WAS NO FLOW ON THE MASKS. CREW OXYGEN GAUGE READ 200 AND PAX GAUGE 300. I BELIEVED THAT FATIGUE WAS A CONTRIBUTING FACTOR ON MY PERFORMANCE EARLY IN THE MORNING. BUT MY POOR PERFORMANCE DURING THE PREFLT, AND SUBSEQUENT LEGS, WAS DUE MOSTLY TO COMPLACENCY. I JUST FAILED TO DO WHAT I WAS SUPPOSED TO DO. I MADE NO CONSCIOUS DECISION TO OMIT THIS ITEM, BUT TIME AND AGAIN, I FAILED TO CHK THE OXYGEN. THE LESSONS I HAVE LEARNED ARE HOW IMPORTANT EVERY CHK CAN BE AND TO NEVER ALLOW YOURSELF TO SKIP OR OMIT ANY ITEMS. THE CHKS WE PERFORM ON A ROUTINE BASIS ARE ANYTHING BUT ROUTINE. I WILL ALSO TREAT AN ACFT COMING OUT OF MAINT WITH MUCH MORE CAUTION AND DOUBLE-CHK EACH ITEM.

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.