It has been proven twice in the last couple of years (Italy and Florida) that a light aeroplane can be flown into a high rise building without doing any serious damage.
If I were a terrorist, I would be thrilled to bits: "We used aeroplanes last time - been there done that - so while they're obsessed with destroying the GA industry, we can crack on undetected and unhindered with our next generation delivery system."
Rattus