Originally Posted by englishal
A far simpler and cheaper option IMO, which would not force transponders on aircraft that can't have them would be to introduce Mode C vales, like the US has. So if you want to operate within 30nm (or whatever) of an airport while remaining outside their CAS you must have mode C fitted and be transponding. If you want to enter their CAS, you will require Mode C and an ATC clearance, and to enter airways Mode S.
This way VFR bimblers in simple machines can remain outside of these areas, and go about their business not transponding or communicating. Training aircraft and people who enjoy the freedom of flying on long cross countries would require Mode C as a minimum, as many already have. Funkier machines or people who use their aircraft as a form of transport under VFR and IFR in the airways would realistically require Mode S.
How does that work in:
The area between Heathrow and Gatwick
The area between Luton and Stansted
The LLR near Manchester
Do those areas become "exceptions", do we just accept that non-transponder aircraft can't use them, or have I missed something?
Infact, having just looked at a chart, by the time you've put veils that size (or similar) around a couple of the busiest airports in the south-east, you've decimated gliding at Lasham and Dunstable (and others, but you get the idea) made places like Southend/Blackbushe/NorthWeald! (and others, but you get the idea) all transponder-required airports.
May as well just make it a mode C veil from Coventry south