What do Will and Claire see and hear as they are considering skipping school on September 11?

Claire sees Will and stops to talk to him. She apologizes for being so rude the night before. Neither of them hears the sound of a jet engine until it roars right above their heads. They see a plane flying on its side close to the tops of the trees. It is so close they can see the rivets on the wings. Then they hear the plane hit the ground.