I had a weird dream that I was the pilot of a 747 jumbo jet and somehow the autopilot failed but instead of turning off, it was stuck on and began to control the plane and take it through a tunnel. It was just big enough for the plane to fit but still parts of the plane were torn off and the power almost failed. Passengers were told to go in brace positions. I had to fight for control of the aircraft. Eventually the autopilot turned off and I had control again but had to guide it carefully through the tunnel. Just as we saw the end of the tunnel, a train went by the end of the tunnel since it intersected a railroad and me and the copilot had to carefully bring the nose of the plane up without hitting the tunnel roof or road. At first the elevators seemed to be stuck but we pulled real hard and were able to pull out of it just in time and barely missed the train. We made it out of the tunnel, almost clipping electrical lines, and went back up into the air and made preparations to make an emergancy landing at the nearest airport. Scary at first but a huge relief when we regained control. Not sure what this dream could mean.