Thomas Borchert wrote in
:

(i.e. it's a "fake" interrogation).

and those are great for passive traffic detectors.

Agreed, *if* they do it. TCAS (and the related "Skywatch" and the like)
definitely send out their own interrogation pings (which would, of course,
NOT be picked up by the traffic detector). But the earlier poster implied
that just because the aircraft had Mode-S the traffic detector would see
it. I am not positive, but pretty sure that this is not true. I don't
recall any requirement for autonomous interrogate *or* response in the
Mode-S spec.

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James M. Knox
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