There are a few AA guns around the maps often next to the flags. You will find a few issues with them. Firstly the bomber can do a full fly-over taking full hit damage and survive. You won't. The fighters take far less damage, but a good pilot will know the AA positions and either stay clear or come up and blind-side you. Again you die.
To be fair I don't mind a good pilot getting me, but its daft when a paper bomber can take so much damage.
edit: just looking at patch notes and they actually did it they nerfed the useless AA:
- Reduced impact damage to planes by 50% for fighters and attack planes and by 40% for bombers