B737-300
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 93
Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Human Factors; Procedure; Manuals
Aircraft had MEL 28-7-04 (center tank Fuel Quantity Indicator inoperative). Proviso B2 of the MEL allows us to depart with the center tank verified as empty; defined as turning on the center tank pumps and observing both low pressure lights illuminated for 15 seconds. If the lights extinguish; the fuel in the tank is to be burned or transferred out. Since the Center Tank fuel pump low pressure lights did not illuminate steady; we attempted to transfer the fuel out of the tank. AOM 16.12.4 directs turning off the Center Tank pumps at the first indication of fuel pump low pressure; which occurs well before the point at which both lights will illuminate steady for 15 seconds. Based on what I observed; I'm confident that we did in fact depart with a center tank that was essentially empty; but the guidance we have puts crews in a position where they can not fully comply with both the AOM and the MEL in situations like this.
B737-300 Captain reported confusion in attempting to comply with MEL and AOM with center fuel tank indicator inoperative.