A United Airlines flight got stuck in the mud Tuesday at Raleigh Durham International Airport.An airport official said the plane was getting ready to take off when it took a turn too sharp and went off the concrete.One wheel ended up in the mud.No one was injured and the passengers were taken off the airplane and put on another flight.The airliner was scheduled to go to Newark, N.J., and now a mechanic is coming to try to free the plane.