Saturday air is classified as PT work, as such is out of FT classification, the same as if you tried to use seniority to work preload as a FT driver. The proper way to fill Saturday is ask qualified pt (Saturday air sheet) ask FT, force PT qualified, force FT. Think of it like New Year's Eve in that respect. As a FT driver you a guaranteed the right to work 40, passing on your regularly scheduled day doesn't give you rights to make that day up on Saturday. Ask me how I know and I'll show you a grievance the size of some of your weekly checks.
Ask qualified PT
Ask FT with 4 or less days worked
Ask FT with 5 days worked
Force PT qualified
Force FT with 4 or less days worked
Force FT with 5 days worked
One of the problems is...which facility do you pull (ask) the FT from?
We have several bldgs and 1 airport.
Ft can demand to punch in at their own building.
When this happens in one building they ask FT drivers from a different building to work from the airport. To catch management doing this requires someone to monitor the people working out of the airport on Saturday, or a random driver being spotted and talked to delivering on Saturday.