Nearly half of Northwest Airline's unionized employees continue to work without new contracts, more than two and a half years after the agreement that cut their pay expired. Typically airline employees threaten to strike as a way of putting pressure on management. But an alternative tactic often referred to as "CHAOS" is growing in popularity among some unions. "CHAOS" involves small scale SURPRISE work interruptions designed to trigger domino effects. Northwest's flight attendants are threatening a version of CHAOS if negotiations break down. The union the airline's mechanics voted to join is an even more enthusiastic proponent of the strategy.