Two comments.
(a) in regard to the 744 aft tankage, the tank does provide a longitudinal balance input but the standard Boeing fuel use procedure does not optimise CG control to the Nth degree as it is not critical other than for payload-limited extreme range flights where every fuel burn kilo saved is a bunch of dollars generated in increased payload availability.
Qantas, which has just this problem going over the pond to the west coast, did a study several years ago and came up with a variation on the basic fuel use protocol and saved (if my recollection is correct) something in the order of 100-200 kg of fuel per sector ... which, of course, permits the carriage of MONEY-generating payload.
Interestingly, the program was generated due to internal lobbying by a pilot who had a bee in his bonnet over trim drag fuel penalties on such operations. Apparently, the ops eng people were a little surprised at the magnitude of the profit benefit.
I don't know whether the procedure was adopted in line ops after the study ... perhaps one of the QF chaps might comment. I had a jumpseat ride for part of cruise on a QF 744 mid-01 and clean forgot about this procedure and forgot to ask the crew on that occasion.
(b) in regard to filling centre wing tanks (and fuselage aux tanks) last ... this is a generally applied technique to maximise ZFW availability due to wing bending relief as indicated by Tinny. As a for instance, over the years aircraft, especially freighters, have been recertificated to higher MZFW limits by rescheduling fuel usage protocols to include a requirement for minimum outboard tank quantities to exploit the bending relief benefits. Ansett, for instance, did just this when the Golden Goose (L188 Electra) fleet was modified from pax to freight .... memories ....
Last edited by john_tullamarine; 27th Nov 2002 at 22:27.