Pilots and managers at Mesaba Airlines must decide whether to allow an arbitrator to design a new contract. If either party rejects arbitration, it would clear the way for a possible strike. A walkout could disrupt air service to smaller communities in Minnesota and other parts of the country where Mesaba flies. The Minneapolis-based carrier flies connecting routes for Northwest Airlines. This morning the National Mediation Board declared the two sides were at an impasse, and more talks would accomplish nothing. Minnesota Public Radio's Jeff Horwich reports. (Three more days at the bargaining table could not solve a contract dispute now well into its third year.