"Steven P. McNicoll" wrote in message
m...
paul kgyy wrote:

Is it normal practice for a Mode S transponder to display the aircraft
tail number to ATC?



No.

It isn't displayed to controllers, but a ModeS transponder does transmit its
serial number which can be read using tools not available to the controller.
The serial number does translate to the N number so long as the transponder
is correctly registered. As of now this technology hasn't been implemented
to the controller, nor is the serial number recorded in the continuous data
recording archive.