Surprised that it's still chain link fencing. I got involved in perimeter security in a railwa rolling stock depot context a few years ago and we went for high spec weldmesh panels topped with razor wire (and warning notices about the razor wire to protect our lawyers' ars*s against the risk of injury to the little tinkers with spraycans). The fences can be double-skinned to increase resistance to break-in. Still vulnerable to some extent to attack by circular saw, but time to get through the fence is significantly increased. It strikes me that if rail companies can make a case for this investment to protect against graffiti attacks, the air industry should be able to do so on the basis of the order-of-magnitude higher risks involved. But then what do I know....