Most of you were about right. I found the Lancs in the general area of the '?', heading directly to the ammo factory (a target much more likely than the refinery). While disposing them, I spotted another set of buffs almost on deck more to the south, Arados. I managed to get one of them, too.
A short time later another set of Lancs tried almost the same route, but this time they bailed when I got into range. All players were members of the same squad.
But then, we are all wrong, because such a reasoning is obviously not allowed in Aces High: