Originally Posted by
Flying Binghi
We may not have a civilian usable GPS signal in 5 years.
Are you referring to the US-controlled GPS constellation specifically? or GPS/GNSS more generally?? If the former, then the US has always been able to 'tweak' the accuracy in certain contested regions and if the latter, it's only the lazy/stupid terrierists that would rely on civilian GPS in a war zone - everyone else sets up their own (classified) positioning systems anyway.
Even though Australia now has a highly-paid 'Space Command' with a remit to ensure Aussie satellites and signals don't get tampered with (exactly how they'll do that is anyone's guess), perhaps on final approach GBAS has it's advantages after all.
I get the impression we went with SBAS partly because it was cheaper than installing GBAS stations at every major airport.. but others here may know.