Originally Posted by CBreezy

Airport reserve isn't a RAP. Short call or long call is. Airport reserve is flight duty. If you are on airport reserve prior to a flight segment, it counts as FDP. If you are on short call reserve prior to a flight segment, it does NOT count as FDP. If you fly a leg and are placed on airport reserve, then are subsequently scheduled to fly a leg, you must count all time spent in airport reserve as duty and cannot accept the assignment if you will exceed your FDP.

I just remembered something from a clarification I received: Here's where it gets really vague. If you are scheduled for airport reserve and pick up a trip at the 10 hour mark, assuming you start at 0600, you will only have 2 hours of duty remaining and the entire 12 hour period counts toward your cumulative for 168. If you are not scheduled to fly, the x hours you spent on reserve does not count toward FDP cumulative limits.

In the example above, you're correct in that it wouldn't technically be FDP until midnight. However, if you are assigned at 2200, all of it would count as FDP and need to be considered. It's no different if you are scheduled to deadhead at the very end of your legal FDP.

The moral of the story is, it is a legal assignment and no 10 hour rest is required prior to being assigned it.