Big John wrote:

I'm not up to speed on current traffic control radar and if they both
'skin paint' and look at transponder returns?.

What you're calling 'skin paint' is what ATC calls "primary radar". The ATC
system that processes transponder returns is called "secondary radar", also
known as ATCRBS (Air Traffic Control Radar Beacon System).

Both kinds of radar operate simultaneously and using antennas that rotate together.

Occasionally you'll hear that either primary or secondary radar is out of
service at a particular facility. If secondary radar is out of service they have
to use some other means of identifying the primary radar returns. If primary
radar is out of service, they can see only transponder-equipped aircraft.

Remove SHIRT to reply directly.
Dave