Emi wrote on Feb 6^th, 2011 at 7:27am:

But now i'm wondering if it's also possible to destroy Addon AI aircrafts like the ones from Ultimate Traffic 2007, or is that only possible with default aircrafts? Also i'd like to know the same about buildings.

The Weapon is lethal to any AI aircraft/rotorcraft regardless of manufacturer. To the sea and ground traffic as well (except cars on highways).

Building - no. But we can add that (see further development topic).