There is an American training film from 1944 - five American flyers are captured and a German intelligence officer, major von Boehm, obtains information on their unit, using quite clever methods, and is able to advise his commanders on the American plans.
In this game there are some simple techniques you can use that will help you to make some guesses on where the enemy planes are.
If you need to see where exactly the enemy plane is on the map, you can plan your route through the area where the enemy is likely to be (you saw him flying that way). Of course if he used his other action point to change the course, then this method will not work. But if you did not, plan your route and, if you suddenly get a curve in the line, that is the place where he is.
This works in Lwow scenario if you did not get both Soviet planes in the second move. I also used this method to spot enemy planes in Epic Wjasma scenario.