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Mode A transponder

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Airspace, FAA Regulations, General Aviation

Is mode A transponder required in Class E or G airspace 30 s.m laterally and below 10000 ft from Class B and C airspace?

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1 Answers



  1. Ash on Feb 26, 2014

    I think you may be refering to the regulations concerning Mode 3A/C transponders in 91.215. To summarzie, you need a Mode 3A/C (an altitude encoding transponder commonly found in most training aircraft) if you want to fly in:

    1. Class A, B, or C airspace
    2. Within the 30NM Mode C veil of a Class B primary airport from the surface up to 10,000MSL
    3. Above the ceiling and within the lateral boundaries of Class B or Class C airspace up to 10,000MSL
    4. All airspace at or above 10,000MSL (excluding the airspace at and below 2,500AGL)

    There is no mention of excluding Class E or G airspace, so the implication is that if scenarios 1-4 apply, than yes you do need a transponder (with Mode C).

    If you are only equipped with a Mode 3A transponder, you should advice ATC (prior to entering the airspace described in scenarios 1-4). You can read about this in 91.215(d) “ATC Authorized Deviations.”

    Hope this was helpful.

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