On Monday, March 19, 2018 at 3:52:28 PM UTC-5, Mike Schumann wrote:

The FARs require that all transponder equipped aircraft have their transponders turned on whenever they are airborne.

Actually, no; as Dan has pointed out, when aircraft are in formation (which is a specific case - not just a bunch of aircraft in the same area, like a gaggle), only the flight lead is supposed to have his transponder on; the rest are supposed to be in standby. In pre-Mode S days this was essential as multiple Mode 3s responding in the same area at the same time would overwhelm the SSR system at worst and trigger all sorts of collision alarms at best.

When the formation breaks up, the wingmen are then supposed to turn on their transponders. Releasing from tow is breaking up the tow formation, so...

This applies to all military and civilian formation flights.

Kirk
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