I'm on the last UK mission where you have to kill three fighters to allow the slow old junkers carrying the top secret stuff to get away.
I've got one soldier, a working armoured car and three trucks to block the runway with. I don't have any AA guns and the Panzer IV has a single AT shell left, a broken track and no fuel.
While the first two planes are happy to run into trucks parked on the runway the third plane seems to fly too high to hit anything. Unfortunately with the five armoured vehicles roaming about it's difficult to get more than a couple of seconds of firing before my soldier gets killed and aiming at the plane is hard.
Which weapons will definitely kill the plane and does anyone have any ideas where I should fire them from?

You can pause the game to issue orders and go into a slow motion mode. Have you tried putting it into slow motion mode to hit the last plane?
Also what happened to the AA guns on the run way? If you had one of those it would make this mission way easier. They could rip through the incoming tanks/trucks and the last plane when it shows up.

I blew them up, when the briefing said I'd have to defend the plane I was assuming it was during refuelling and take-off which I'd rather do from the bushes than with AA guns.
Slowing down helped me hit the thing with a tank but the shell apparently didn't have any effect.
In the end I set up two trucks in a position to rip one wing off the first two planes and ran the sequence through a couple of times until I ended up with a plane lying on it's side with it's unbroken wing sticking into the air. When the third plane came along it hit this and crashed.

Wow must have taken a bit of luck to have the plane wing be in a postion to take out the 3rd. Those AA guns are easily the best way to complete that mission though, they wreck not only the planes but also all the tanks and trucks in a few seconds.