"Larry Dighera" wrote in message
...

However, a full blown mode C transponder may not be necessary.
A radar reflector like they use on weather balloon ought be
sufficient. It is just a piece of foil with a large cross section.


That's a constructive suggestion.

How large must such a radar reflector be?

Will it activate TCAS?


No.



Does ATC normally enable the display of primary targets?


Outside of Class A airspace, yes.