One plausible scenario is that the plane was hijacked by terrorists so that it could later be used to deliver a payload (or be the payload itself a la 9-11). S

One plausible scenario is that the plane was hijacked by terrorists so that it could later be used to deliver a payload (or be the payload itself a la 9-11). Since the plane has such a huge range, it could be used in an attack on American soil. This could also explain flying at a high altitude as a way to kill the passengers.