KLOTEN, Switzerland (Reuters) – More than 300 pilots marched on Swiss International Air Lines headquarters near to Zurich airport on Thursday to press their contract demands ahead of a possible walkout next month. Pilots at Swiss, a unit of Deutsche Lufthansa, have been working without an accord since April after management rejected a tentative deal from initial talks, the Aeropers union has said. The union has been polling members on strike action, and has said a walkout could take place from Oct. 17. Swiss management has offered to take the case to an arbitration panel, while pilots have mad…