Hi Guys,
The PC-9M with sidewinders would be a credable point defence capability. This allows the aircraft to wait in one area until something illegal comes in and is then engaged. The Super Tucano shown is used to intercept drug runners in prop aircraft and nothing else. Three problems though:
1. Its not point defence that is required (If anything) it is an intercpetion capability. To intercept an airliner doing Mach 0.82 the aircraft would have to be considerably faster ie expensive.
2. No airforce would allow the shooting down of an aircraft over its home soil without the target being visually intercepted, identifed and warned. See point one.
3. The COS dosent have the balls to make an executive decision to shootdown a rouge aircraft. During the May Day visits I believe this was to be handed on to Bertie for decision. ie another layer of complication who is also probably in the main target area for a terrorist threat!