We all know that you can't fly in Class B airspace without a transponder. But, when doing a formation flight, only the lead plane has their transponder turned on. Does that mean that it's possible for a non-transponder-equipped airplane to fly through Class B airspace so long as they're part of a formation flight?

If so, would they need to arrange it ahead of time with the ATC facility, or could they just notify ATC when they're requesting entry to the Class B, or do they not need to even tell ATC that one of their planes doesn't have a transponder (not saying that the last option is a good idea, just asking if it's legal).

  • $\begingroup$ Closely related, but doesn't address the question of aircraft that don't have a transponder $\endgroup$
    – Pondlife
    Commented Feb 11, 2022 at 16:49
  • $\begingroup$ Would you be VFR, or IFR in IMC? One time flight, or plan to operate that way regularly? $\endgroup$ Commented Feb 12, 2022 at 1:15

1 Answer 1


FAR 91.131(d)(1) makes no exceptions regarding the transponder requirement for an aircraft operating as part of a formation flight in Class B airspace even though that aircraft may have its transponder turned off as part of the formation flying procedure.

FAR 91.215 (d)(3) states that a request for deviation from the transponder requirement can be made to ATC at least one hour before the operation.

While it may seem reasonable that since the aircraft in question (the one without the transponder) is planned to not have its transponder on anyway, there are some good reasons (at least to me) that a specific ATC deviation/approval from the requirement is necessary.

Among those reasons:

  1. The regulation says exactly what it means;
  2. If the formation flight gets spread out (beyond a mile or so) ATC may ask for the trailing aircraft (perhaps the one without the transponder) to turn its transponder on.

Perhaps some other reasons as well.

So, if you plan on operating a non-transponder equipped aircraft in a formation it would be appropriate to contact the ATC facility having control over the particular Class B airspace at least one hour before the proposed operation.


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