Unionized pilots for Air Canada denied Sunday they were a taking job action as fog and a runway fire in Toronto canceled as many as 100 flights. The Toronto Star said Air Canada pilots began phoning in sick late Saturday and early Sunday as fog moved into both Toronto and Montreal. Adding to travelers\' woes, a small fire in an underground runway conduit led to air traffic controllers reducing the number of arrivals from 50 per hour to 12, with the rest being diverted elsewhere, the Canadian Broadcasting Corp. reported. Some unionized 3,000 pilots are at a contract negotiation standoff with the airline. Friday, the federal Conservative government imposed a back-to-work legislation bill, the third time in a year various Air Canada unions have been blocked from striking. However, pilots have international opt-out work options ground workers don\'t, such as fatigue. The Star said some pilots had posted Twitter messages denying there was a labor-related job defiance movement.