Unfortunateluy, there is a very us against them attitude between management and union employees. This often results in friction between those factions and adds enormously to the stress load in the working environment. It also causes communcation breakdowns at a very basic level as there is no real trust between these levels.
Never trust a manager. All they want to do is fire you so they look like a tough guy. Some may seem like friends but they'll stab you in the back and lie / gang up on you just as soon as they try to pull you in the office. Don't trust anyone !