But because most KC-135s cannot receive fuel in flight, they have to carry that fuel and weight back to their base. The average amount of fuel returned to base is 35,000-40,000 lb. per aircraft.
Qué? What he mean??
The tanker will always need enough fuel to return and land safely - I don't know what the Spams do, but the UK always had a 'minimum off-task fuel' (MOTF) which was the fuel state needed to RTB with sufficient fuel to be able to go-around, transit and land at the alternate, plus appropriate contingency fuel.
Whether or not the tanker can refuel itself in flight merely influences the on-task time, not the MOTF. Reach MOTF and Bingo, home you have to go!
Surely the Spams aren't considering letting a
tanker become tanker-dependent on an AAR anchor? Or flying without enough fuel for an alternate?
Efficient tanker planning has always been rather more of a European thing than a US thing, simply because the US usually had the luxury of just opening another tin of 135s and filling the sky with jets rather than having to work out a 'cunning plan' with just a handful as the UK is obliged to.
In GW1, we often used a pair of VC10s outbound with the attack formation, then one would transfer any surplus to the other before going home, leaving only one contingency tanker available for unplanned AAR if the attack formation needed it. Perhaps that's the sort of thing McNabb actually meant - transfer spare gas to another tanker and RTB at MOTF?