In this clip some GA plane busts Heathrow's class A and they divert the jets away from him. The GA plane is squawking 7000 but has no mode C or hasn't turned it on.
My question is twofold:
1. Do you see his altitude on your primary return on the radar?
2. If you don't see altitude, are you relying on the mode C return solely for altitude? Because a mode C return can obviously be altered and be incorrect - I've many times flown with them being well off or have the wrong pressure altitude input.
How does this work?