You green slip on your days off while on reserve. It is ideal to start the month off with four days off and get a green slipon the first day. Let's say you get a 4 day worth 23 hours. You get 4 pay back off days tacked on to the end of your trip, and are payed that 23 hours above the reserve 70 hour guarantee. Now you have 93 hour month and you've only flown 4 days so far. It's called rolling thunder because every time you green slip on days off you get payback days and don't get used on "real" reserve days hardly at all. Obviously, the company hates this. I've seen instances on the ER where some guys get 150 hours pay and only fly 80 hours.