Days after changing its pay policies, United Airlines Inc. faces a class action brought on behalf of employees who claim the airline forced them to take unpaid time off.

The class action, filed Wednesday by attorney Douglas Werman, of Chicago’s Werman Salas, alleges United’s vice president of human resources sent a May 4 email to all management and administrative employees requiring them to take 20 unpaid days starting May 16. The International Association of Machinists and Aerospace Workers (IAMAW), the nation’s largest union representing airline workers, filed a similar suit May 5.