Photos show a dented central window pane with cracks in multiple areas but the cause of the damage has left investigators scratching their heads. The crack in the four-layer thick glass left cockpit crew terrified as the plane made its transatlantic voyage. The incident occurred three hours into the flight as the jet flew between Greenland and Iceland and forced Virgin Flight VS41 to make a U-turn and fly back to the UK on May 27. Experts have said that the plane's altitude meant it could not have hit a bird and no immediate other course have been highlighted but...