Right now if an airliner wants to fly a really long distance (eg., a Boeing 787 flying from Seattle to Tokyo), it has to load itself down with lots and lots of fuel, which in turn weighs thousands and thousands of pounds. This, of course, makes the flight of the aircraft less efficient than it could be1. Thus, if the craft could theoretically carry half as much fuel, that should increase the fuel efficiency of the craft, right?2
Mid-way refueling seems like it would be a Good Idea™ at that point. Of course, landing would add a heck of a lot of time to the flight, so it seems the better option would be mid-air refueling. It would allow for the aircraft to be more efficient, without the need for stopping on a long journey.
I assume that, because Airbus and Boeing's engineers and sales managers are really quite smart, they have a really good reason that they don't fit/sell this feature on any civilian transportation aircraft. But I'm not sure what that reason is.
Does anyone know why airlines do not use aircraft that are capable of mid-air refueling?
1 If I'm not mistaken, increased weight means an increased AoA to maintain level flight, which in turn increases induced drag from the wing. Less fuel would mean less induced drag or, if mid-air refueling were common practice, a wing that was designed to be more efficient because it was required to handle less weight.
2 I don't know by how much, if it's not that much, well, that might explain why nobody does this.