When planes are flying in formation, TCAS will undoubtedly alert the crew. As a result, in this instance, the transponder must be turned off. The pilot must, however, rely on eyesight rather than displays and sensors which can be difficult for them to fly closely. Please correct me if I am wrong until this point? Is it therefore necessary to turn off the transponder when flying in formation? Or pilots are instructed to fly their plane by a certain speed and attitude at a particular location beforehand?

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1 Answer 1


See also: In a part 91 formation flight within a mode C veil, are all the aircraft required to have their transponders on?

Yes, the transponder should be off/standby. From AIM 4-1-20-a-4-c

(c) When participating in a VFR formation flight that is not receiving ATC services, only the lead aircraft should operate their transponder and ADS-B Out. All other aircraft should disable transponder and ADS-B transmissions once established within the formation.


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.

  • $\begingroup$ Correct in most low-altitude areas, but I don't believe the AIM can be used as a justification to violate the FARs. Namely: within 30NM of a Class B airport, above Class B or Class C airspace, and above 10,000 MSL, all aircraft should have an operating transponder set to report Mode C altitude unless specifically instructed otherwise by ATC. (On our side we won't get alarms for two 1200 codes right on top of each other, while we do get alarms for a 1200 code conflicting with a discrete code.) $\endgroup$
    – randomhead
    Sep 27, 2021 at 12:42
  • $\begingroup$ When I wrote this, I forgot to check for existing answers. aviation.stackexchange.com/questions/56490/… is slightly different in scope, but has information on the ATC side. $\endgroup$
    – BowlOfRed
    Sep 27, 2021 at 20:01
  • $\begingroup$ @BowlOfRed So, Do pilots feel relatively any difference (inconvenience) after turning off their transponder? $\endgroup$
    – Auberron
    Sep 28, 2021 at 6:10
  • $\begingroup$ during this flight? $\endgroup$
    – Auberron
    Sep 28, 2021 at 7:34

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