I've been piloting for more than 10 years and I'm a UAV enthusiast but, I'm sorry: Globalhawk is piloted by humans, it has the same autopilot that any good airplane has, including a (similar) ILS-CAT-III and inertial system. (in fact, they use EXACTLY the same honeywell/rockwell autopilot than most modern planes) Yes, it can land and take-off on it's own (in specific circumstances), just like ANY Airbus and Boeing NG does. Autopilots do not fly airplanes, they just move control surfaces based on angles and speeds, it's just a script/formula. It does not learn how to react to unexpected situations, and it does not accumulates experience: required to "override" information read by instruments. Making a car that follows marks on ground is not driving. It took decades to make cars actually drive them by themselves, yet, they cheat by using radars.