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5 Answers

Transponder 91.215

Asked by: 10000 views , ,
FAA Regulations, Private Pilot

Is a transponder required in class E, D or G airspace? The regulation isn't clear to me.  To me it lacks saying that it is required in class D, E, G.  Therefore it is not required.  Can any point out where it says or doesn't say that a transponder is required.

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5 Answers



  1. Lucas on Oct 30, 2014

    Well a transponder is required above 10,000 MSL excluding the airspace below 2,500 feet AGL. Echo and Golf airspace would definitely qualify and if a Delta airport extends upwards of 2,500 feet AGL and is located above 10,000 MSL it would also qualify.
    Also if you fly at a Delta airport that is located within 30 NM of a Bravo Airport you would again need a transponder. For example I fly out of morristown (Class D)but need a transponder as it is close to Newark.

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  2. tommytom on Oct 30, 2014

    Ok I agree with you. Transponder is required above 10,000 MSL. Not required in airspace below 2,500 AGL.

    What about clas D below 10,000 MSL?

    Class E below 10,000 MSL?

    The reg does not mention this airspace.

    This part of the reg confuses me. “Transponder on operation. While in all controlled airspace”

    (c) Transponder-on operation. While in the airspace as specified in paragraph (b) of this section or in all controlled airspace, each person operating an aircraft equipped with an operable ATC transponder maintained in accordance with §91.413 of this part shall operate the transponder, including Mode C equipment if installed, and shall reply on the appropriate code or as assigned by ATC.

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  3. Lucas on Oct 30, 2014

    All that it means is if you have a transponder it should be on or on alt at all times. All that does is make the airspace safer as ATC is able to see you and time permitting resolve traffic issues.
    If you do not have a transponder then its a no issue but if you do have it, it needs to be on at all times while in controlled airspace to make the skies a safer place…

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  4. John D Collins on Oct 30, 2014

    Class D, E, and G don’t trigger a requirement for equipage of a transponder, but may be included in other airspace that does trigger the requirement. Example any airspace above 10,000 MSL excluding airspace 2,500 AGL (this encompass D, E or G airspace). Another example is any airspace within the 30 NM mode C veil.

    The equipage requirement is described in 91.215(b). 91.215(C) deals with when it must be on if a transponder is installed and operating. It includes all the areas that it is required for equipage. It also includes all controlled airspace which is a generic term for any airspace other than G. To be specific, this means if you have a transponder installed, it must also be on in all class E and D airspace.

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  5. Kris Kortokrax on Oct 31, 2014

    I would differ with Lucas and John on one point. 91.215 (c) states that the transponder shall be operated if there is a transponder installed AND maintained in accordance with 91.413.

    91.413(a) forbids use of the transponder if it has not been tested and inspected in the previous 24 calendar months.

    Ideally, aircraft owners will see to it that the transponder is maintained. If it has gone past the inspection, don’t turn it on just because you have it. It may be broadcasting false information, which could be worse than no information at all.

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