What a bizarre statement. Voyager is tasked by the MoD, they control where they want the aircraft to go, so one would assume this planning activity takes place some weeks before the flight, after of couse the MoD are appraised of the aircraft available. With the limited Voyagers (is it 8?) at the moment, it;s fair to assume they can't be everywhere at the same time, there being the need to charter in until the full A330 fleet is available. Who'flying the TCX aircraft? Air Tanker crew or TCX? Scheduled, regular flights I'd imagine? Aircraft allocated, crew allocated... no problem