if you have installed some mods, which are forbidden, it could be a reason.... some servers have automatic cheat and mod protection, so I suggest you uninstall LFS, and install fresh LFS withoud mods or so.... this is only logical explanation why are you banned for no reason.....
other thing, on AA servers we dont ban people who come to our servers,
only severe crashers, hackers and multiple accounts are banned, so dont have a clue what went wrong?
do you possibly have a replay of a race on AirAttack server when you were banned?
it could help, cos you can report it to official AirAttack forum at airattackteam.com....
cheers....