FB, you have converted me. There is a very real, prescient risk that the entire ATC system would have to revert to procedural control in the event of a terrorist attack using GPS guided weapons. This reversion represents an unacceptable risk, certainly. Procedural control, as used across oz and every ocean in the world, is just the sort of blatant terror-cherry-ready-to-be-picked-type thing Al Quaida search the world hoping to have invoked.
I suspect that when you make statements about the robust ATC system being terrorist proof, you have never actually visited a centre. A man with a pistol could take one out for days, and if carrying explosives, weeks/months. Imagine if the terrorists got their hands on TWO pistols, and TWO explosive vests? My god....
Then I've just realised- what if they woke up to the vulnerability of the power grid....imagine what a couple of truck bombs could do....no power in a major city for weeks/months..... no traffic lights, no refridgeration.....this could happen without warning at any time!! I know you will join with me in lobbying the govt to ban road use and refridgerated food. Lets set up outside Coles tomorrow- the people must be warned of their folly! I'll let you choose which Coles; I'll bring the foil hats.
I forgot about the dams.......but then again, it's far more likely that terrorists will build marine-launched flying GPS guided buzz bombs capable of delivering a payload from off-shore that will be big enough to be effective, yet small enough to evade detection, enabling repeated attacks requiring the shut-down of the GPS constellation......sort of an invisble, floating, GPS-guided V2 rocket launch vessel. That's MUCH more likely than anyone with a pistol, explosive jacket, or truck bomb.....right? Right?