So one is not really doing anything ..is it just left off untill the first
quits?


"Steven P. McNicoll" wrote:

"Teacherjh" wrote in message
...

How does a second transponder fit in to the datastream? Aren't they both
transmitting the same data at the same time on the same frequencies? Wont
that
interefere with itself?


The second would only be used if ATC reported a problem with the first one.