As i understand it, yes you can be forced to work. If you refuse, they can take disciplinary action if they desire. Management is to ask for volunteers first by seniority and then FORCE from the bottom up. At our center they always force ALL air drivers to work and then base the number of drivers extra they will need and go from there. I allways used to jump on the easy day and easy double time pay and request 8 hours.. GGGGRRRRRAAAAAAVVVVVYYY!!!!!!!!
P.S. I know some guys who try to get a vacation during that week just to keep from being forced to work. Of course only a few get that week.