[Mobhack]

I bet you are plotting them to fly right over the enemy side of the map, where they will meet his AAA?.

Fly the first mission over your own territory, with entry and exit lines on your side of the map. See if anything shoots at them, and if not, plot the next mission nearer to his front line. Repeat as long as you feel its safe - do not enter his AAA envelope, since slow low-flying spotter planes are an easy target.

Spotter planes see things from on high, and so can see at an angle down into his territory, especially moving vehicles.