While the plane is in flight, Joshua refers to updates about the plane's course from ground control. That would not be possible because Ground Control only handles planes on the ground at an airport. Enroute Centers track a plane at cruising altitude.
Stiles:(referring to Lex's computer) Are you going to go throug withdrawal if you're away from that thing for too long?
Lex: Yup. And you wouldn't like the drooling and twitching.