A and C. I was searching for something on Mode S and found this old thread. I think it's worth ressurecting cos a lot of people have their heads in the sand over the introduction of Mode S (and I'm bored

).
I for one didn't realise that the Mode S is supposed to transmit HDG and IAS in a digital format or otherwise. Well that effectively prevents it being fitted to 60% plus of the aircraft registered in the UK then. <img src="rolleyes.gif" border="0">
Excellent plan messers CAA, what are you going to come up with next? <img src="confused.gif" border="0">