Hi Weasel,
I just had a Hurricane shot down by my PBEM opponent (Vesku) yesterday. The plane crashed onto the battlefield. I didn't see a chute
There was quite a few different guns firing at the poor bloke.
I think it helps if the AAA are stationary.
You may need shots left at the end of your turn; so I don't think you can use them to shoot up infantry and then expect them to shoot at aircraft in the same turn.
Perhaps you should ask Vesku what he did right.
cheers,
Cross