Why will airport workers go on strike?

The National Airport Workers Union threatened a strike today following the announcement of Blue Sky Airlines, that there will be a salary freeze for all airport workers effective immediately. This is because of the financial difficulties and the decrease in the number of passengers, the airline has been suffering over the past few months. Airport workers had been expecting a salary increase next month. Blue Sky claims that they are acting within the terms of their contract. With the airport workers, Union leaders disagree and plan to strike next week.