Narrative:

Scheduled flight from den-lga. Shortly after passing ord at FL330, a 'B' system low pressure light illuminated. Pressure and quantity held steady, and the flight engineer ran the abnormal checklist. While he was finishing, the other 'B' system low pressure light came on and 'B' system pressure fluctuated. Quantity held steady and system 'a' indications were normal. We consulted with the flight manual and maintenance control and concluded that there was no corrective action that we could take. We consulted with dispatch and informed them that we didn't want to go to lga due to the abnormal flap setting and associated higher approach speed. We opted to proceed to ewr, which had longer runways and better support facilities. In making this decision, we overflew cle, which was probably the closest suitable airport at which we could have landed after determining the nature of the problem as best we could. By the time we, as a crew, discussed the implications of an 'a' system failure, however remote, we were almost as close to ewr as cle and after checking WX found that ewr was more favorable (particularly with xwinds, which were a factor in the approach due to partial rudder loss). We declared an emergency at that time and proceeded to an uneventful landing at ewr. It turned out that there was a leak in system 'B.' the quantity was depleted and there may have been more quantity loss in system 'a' than is theoretically possible. The 'B' system quantity gauge was inoperative and there was something unusual going on with 'a.' lessons: 1. We had conflicting information which initially caused me to not treat the problem with the seriousness that it merited. 2. We overflew a suitable field, which I won't do again. There were a lot of factors that went into that decision. Some of those, such as better support facilities for both customers and maintenance, would really be irrelevant should 'a' system have failed, too. 3. Decision making in a collective environment and coordination between us (and the cabin team) went extremely well. Thumbs up for cockpit crew coordination classes!

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Original NASA ASRS Text

Title: ACFT EQUIP PROBLEM CAUSES A SELECTION OF ANOTHER ARPT FOR LNDG BUT CLOSE TO DEST ARPT.

Narrative: SCHEDULED FLT FROM DEN-LGA. SHORTLY AFTER PASSING ORD AT FL330, A 'B' SYS LOW PRESSURE LIGHT ILLUMINATED. PRESSURE AND QUANTITY HELD STEADY, AND THE FE RAN THE ABNORMAL CHKLIST. WHILE HE WAS FINISHING, THE OTHER 'B' SYS LOW PRESSURE LIGHT CAME ON AND 'B' SYS PRESSURE FLUCTUATED. QUANTITY HELD STEADY AND SYS 'A' INDICATIONS WERE NORMAL. WE CONSULTED WITH THE FLT MANUAL AND MAINT CTL AND CONCLUDED THAT THERE WAS NO CORRECTIVE ACTION THAT WE COULD TAKE. WE CONSULTED WITH DISPATCH AND INFORMED THEM THAT WE DIDN'T WANT TO GO TO LGA DUE TO THE ABNORMAL FLAP SETTING AND ASSOCIATED HIGHER APCH SPD. WE OPTED TO PROCEED TO EWR, WHICH HAD LONGER RWYS AND BETTER SUPPORT FACILITIES. IN MAKING THIS DECISION, WE OVERFLEW CLE, WHICH WAS PROBABLY THE CLOSEST SUITABLE ARPT AT WHICH WE COULD HAVE LANDED AFTER DETERMINING THE NATURE OF THE PROBLEM AS BEST WE COULD. BY THE TIME WE, AS A CREW, DISCUSSED THE IMPLICATIONS OF AN 'A' SYS FAILURE, HOWEVER REMOTE, WE WERE ALMOST AS CLOSE TO EWR AS CLE AND AFTER CHKING WX FOUND THAT EWR WAS MORE FAVORABLE (PARTICULARLY WITH XWINDS, WHICH WERE A FACTOR IN THE APCH DUE TO PARTIAL RUDDER LOSS). WE DECLARED AN EMER AT THAT TIME AND PROCEEDED TO AN UNEVENTFUL LNDG AT EWR. IT TURNED OUT THAT THERE WAS A LEAK IN SYS 'B.' THE QUANTITY WAS DEPLETED AND THERE MAY HAVE BEEN MORE QUANTITY LOSS IN SYS 'A' THAN IS THEORETICALLY POSSIBLE. THE 'B' SYS QUANTITY GAUGE WAS INOP AND THERE WAS SOMETHING UNUSUAL GOING ON WITH 'A.' LESSONS: 1. WE HAD CONFLICTING INFO WHICH INITIALLY CAUSED ME TO NOT TREAT THE PROBLEM WITH THE SERIOUSNESS THAT IT MERITED. 2. WE OVERFLEW A SUITABLE FIELD, WHICH I WON'T DO AGAIN. THERE WERE A LOT OF FACTORS THAT WENT INTO THAT DECISION. SOME OF THOSE, SUCH AS BETTER SUPPORT FACILITIES FOR BOTH CUSTOMERS AND MAINT, WOULD REALLY BE IRRELEVANT SHOULD 'A' SYS HAVE FAILED, TOO. 3. DECISION MAKING IN A COLLECTIVE ENVIRONMENT AND COORD BTWN US (AND THE CABIN TEAM) WENT EXTREMELY WELL. THUMBS UP FOR COCKPIT CREW COORD CLASSES!

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.