Originally Posted by noelf
The FAA has released a new Advisory Circular 90-114B on the use of ADSB. Section 18.104.22.168 covers use during formation flights.
This is the relevant info:
22.214.171.124 Formation Operations. ATC uses established transponder and ADS-B transmission procedures when participating in formation operations. Per the Aeronautical Information Manual (AIM) paragraph 4-1-20, if the formation flight is receiving ATC services, pilots can expect ATC to direct all non-lead aircraft to “STOP SQUAWK,” and should not do so until instructed. For visual flight rules (VFR) formation flights not receiving ATC services, ATC directs that only the lead aircraft should squawk the assigned beacon code (1200). All other aircraft should disable transponder and ADS-B transmissions once established within the formation.