Pretty simple. We have two policies:
Unable to commute
Call in honest
Unable to commute. You need two options to get to base on time. Second option should be Delta, because you will get positive space if you can't make the first option. First option can be nonrev or jumpseat on any airline.
Call in honest. For some reason, you can't make it and you had two options, you won't be reprimanded. You will be docked pay, though, unless you can work out something with CS.