<h1>Carrier suspends planned flight resumptions as 10,000 attendants defy return-to-work order, union vows constitutional challenge</h1> A national carrier suspended planned flight resumptions after the union representing about 10,000 flight attendants said it would defy a Canada Industrial Relations Board order to return to work issued after the federal government referred the dispute to the board. The board ordered staff back pending resolution and extended the existing collective agreement until an arbitrator issues a new settlement; the employer sought government-directed arbitration. The union announced continued strike action and intends to challenge the order as unconstitutional. The stoppage has led to widespread cancellations, passenger refund and rebooking measures, and warnings that normal operations may take several days to restore.