Aside from theft, assault, or something very serious;
the only way to get fired is to file grievances; and possibly win them!
Management will bend and break the contract and it's employees here at UPS. This is nothing new. The deal is, if you make good with your management and bend the rules and "favors", you won't be a target.
Once you stand up for yourself and your rights and what is "correct", then you're just another duck lined up on the pond! and You will likely be fired by the end of the year. management will persue this to the bitter end..
So the double edge sword exists. fly under the radar and bend but don't break for them, or stand up for your rights as a union employee and face the UPS guillotine...
Pick your poison!