B757-200
Flight Crew Air Transport Pilot (ATP)
Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL
General None Reported / Taken
Human Factors; Aircraft; MEL
Aircraft had 3 MEL's 28-XX-X; 28-XX-Y; 28-XX-Z. There were other issues with the aircraft involving an autopilot and auto throttle that required maintenance to be aboard the aircraft. All the deferrals required long; convoluted language to review so I decided to query the maintenance personnel if all procedures where completed via the MEL. The fuel load was approximately 14.2 in the mains and 8.0 in the center. After reviewing all MEL procedures more than once; we decided that the aircraft was good to go for normal operation per MEL procedures 28-XX-Y. The hidden problem was MEL 28-XX-X that the flight could not operate with the cross feed open. This conflicted with the previous MEL since fuel was in the center tank. Per the center fuel pump inop procedures we took off and fuel was used at a normal point until depleted prior to ZZZ. No other legs after that required fuel in the center tank. Our flight release had no notation the crossfeed valve was restricted. I also operated on the best knowledge that we were being dispatched to ZZZ tankering fuel to ZZZ precluding the need to uplift fuel in ZZZ and that the maintenance personnel provided me information knowing they knew that fuel was in the center tank. These multiple MEL's were convoluted and confusing at best. Our previous flight that day with a flip to a night operation could also been a contributing factor in the form of fatigue.
[Report narrative contained no additional information].
B757 flight crew reports departing with multiple MELs concerning inoperative fuel gauges and discovers; once airborne; that they may have had conflicting requirements.