ADS-B and Formation Flight

Executive Summary (for all who are not reg geeks)

Procedure: In clinics and practice formation flight, Lead squawks Mode C and ADS-B Out. All wingmen STOP SQUAWK, with both transponder and ADS-B off. For the Mooney Caravan procedure, keep reading. Mooney Caravan Procedure: For 2022 we expect our LOA to provide that Mooney Lead and Mooney Tail will have discrete squawk codes. All element leads will turn off their transponders, but will broadcast ADS-B Out. If ADS-B Out cannot be broadcast without the transponder on, then that element lead is to squawk 1200 and ADS-B Out. This way conflicting traffic with ADS-B In will see each element lead, rather than only seeing Mooney Lead and Mooney Tail, which would create a safety hazard by suggesting there was open airspace between Lead and Tail. It will also provide element leads with situational awareness regarding other elements, though this feature must be used judiciously to prevent it from becoming a distraction.

How Do I Kill the Parrot with My Particular Panel?

There are myriad variations in how ADS-B and transponder installations operate. You must figure this out before you're airborne in a formation flight. That's no time to be heads down fiddling with your transponder. Some installations allow separation of functions between transponder and ADS-B output. Others do not. Methods to disable these functions also vary. On some units it's as simple as turning the box off. However, some installations automatically turn back on during takeoff, a particularly poor time to be distracted by a traffic alert and, worse, then going heads down to try to kill the parrot. On some installations the circuit breakers must be pulled.

As a public service, here is a list of installations that have been tested for these operations:

• Garmin GTX 327 transponder and GDL-88 ADS-B Out: if on separate circuit breakers, can likely be configured to both off by pulling both breakers, and to ADS-B only enabled (transponder off) by pulling just the transponder circuit breaker.
• Don't see your equipment here? Mail clippy@mooneycaravan.org and send best practices for operating your transponder/ADS-B equipment.

The Rest of the Story (for those who say "show me")

The FAA makes an exception to the ADS-B Out requirement found in 14 CFR § 91.225 for formation flight. Anyone who's participated in a formation flight where more than one aircraft is broadcasting ADS-B out knows why – any airplane with TIS-B (ADS-B traffic) operating gets traffic alerts reporting traffic dangerously close. The last thing a formation pilot needs is distraction, much less totally unhelpful technology that points out the obvious. In a nod to reality, the FAA amended 14 CFR § 91.225(f) to include this language: This rule is interpreted and applied to formation flight in AC 90-114B, § 4.3.1.3: The specific AIM reference alluded to in AC 90-114B is § 4-1-20 4.(c): Based on this guidance, when not receiving ATC services, brief that Lead will carry the squawk and ADS-B, and wingmen will disable both their transponder and ADS-B. Also brief that if there's a separation or breakout and an aircraft thereafter proceeds apart from the formation, that aircraft must re-enable transponder and ADS-B broadcast. If receiving ATC services, brief similarly, except to provide that Lead will be responsible for coordinating with ATC to confirm this manner of proceeding.