Lillian spots an airplane on radar that is currently approaching in a straight line, and that will fly directly overhead. The plane maintains a constant altitude of 6975 feet. Lillian initially measures an angle of elevation of 18 to the plane at point AA. At some later time, she measures an angle of elevation of 33 to the plane at point BB. Find the distance the plane traveled from point AA to point BB. Round your answer to the nearest tenth of a foot if necessary.