Originally Posted by
Ian W
As zkdli has said if you have a modern secondary radar fit with Mode S you will be squawking the equivalent of your airframe number -
Right, I know what Mode S is and what it does. I also know that there's plenty of planes without mode S. So again, someone starts making pig noises and it seems to be coming from an area with a couple of non-mode S 1200 squawks, none of which are talking to ATC, what call sign do you call out?