Which Tank in use?
Xeque asked: '....Seriously, at that stage of a long flight, which tanks would be in use? Wing tanks, fuselage tanks or both? ...."
Common practice is to use centre tank fuel (if carried) first, as this reduces bending loads on the wing root and increases the fatigue life, as the wing fuel is evenly distributed in the lifting part of the aircraft, whereas fuselage fuel is not.
Since the investigation into the TWA 800 centre tank explosion (a 747), a quantity of fuel may be carried in the centre tank simply to stabilise the temperature of fuel and minimise fuel vapour, even when centre tank fuel is not required for the flight.