I'd imagine a commercial jet to be pretty effective. Ignoring the fact that it probably wouldn't even come close to hitting one, it'd probably hit with more than enough force to make the fancy scaly armor look like cookie dough.
Considering that you can damage them with pointy flying sticks, maybe you wouldn't even need an airplane, maybe you could get away with using an eighteen wheeler or something. Anyone want to do some math and estimate offense ratings for those things?