Are you in management or just a brown noser? If you were set up to fail and had late air and then got a warning letter it's harassment. I've been the steward in that meeting many times and management always act like "how could we have known that giving a driver 20+ NDA's and getting out an hour late would cause late air??"
I was just giving an example.
If you run straight air and you have something late it's not a damn thing they can do to you.
Some morning letters are justified others are not
But when you do get a warning letter and you make sure you file buddy** grievances on everything you can find