Unidentified planes, planes in distress and planes we suspect are being used for illegal activities can then be intercepted by a fighter from NORAD. He says he assumed that hijacked plane was the one that hit the Pentagon, though he could not be sure." He says he assumed that hijacked plane was the one that hit the Pentagon, though he could not be sure." United said it was also "deeply concerned" about another flight, Flight 175, a Boeing 767, which was bound from Boston to Los Angeles. Some of these drills were "Live Fly" exercises were actual aircraft, likely flown by remote control were simulating hi-jacked aircraft.