On Monday, October 16, 2017 at 12:57:35 PM UTC-4, Ramy wrote:
This is disturbing news to hear that the military can not afford to
comply with the ADS-B requirement while GA is required.
And why the wingmen in formation turn off their transponders?

Hi Ramy - IIRC, for civilian formation flying, procedure is normally
the same; only one in formation has transponder on. Why?
Because otherwise they all get interrogated at the same time,
they all answer at the same time, and the result is unintelligible
(this is called "fruiting", kinda like everyone shouting at the
same time - even worse than RAS).

In principal this is less of a problem with Mode S, except a
mode S transponder behaves like an old Mode C when it gets an
old-style interrogation. And while ground stations send new-style
interrogation, older TCAS-I installations send the old-style
interrogation. And these are installed in better-equipped GA
aircraft like Lee's Bonanza.

Darryl, please correct if I've garbled (fruited) this...

Hope that's clear!
Best Regards, Dave