Is a transponder needed to be turned on to operate above the upper limit of class B airspace?


Yes: If you combine the two sections provided by SMSvonder Tann and Raaj Tram you get:

14 CFR 91.215 - ATC transponder and altitude reporting equipment and use:

(b)(4) All aircraft in all airspace above the ceiling and within the lateral boundaries of a Class B or Class C airspace area designated for an airport upward to 10,000 feet MSL; and

(b)(5)(I) airspace of the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL, excluding the airspace at and below 2,500 feet above the surface; and

You can't fly over B or C without a transponder.

There are some specific exceptions for aircraft not originally equipped with an electrical system.



Generally, Class B airspace extends up to 10,000ft. That said, FAA states that:

All aircraft are required to be equipped with a Mode C transponder when flying at or above 10,000 feet msl, over the 48 contiguous states or the District of Columbia, excluding that airspace below 2,500 feet agl.

  • 1
    $\begingroup$ Class B airspace does not necessarily extend to 10,000 feet - consider New York, which tops out at 7,000. Transponder operation is still required, just not necessarily by this particular rule. $\endgroup$ – NathanG Apr 10 '16 at 2:46
  • $\begingroup$ @NathanG - That's why I started with "Generally". Here's how FAA defines Class B airspace: "Class B airspace is generally airspace from the surface to 10,000 feet MSL surrounding the nation’s busiest airports in terms of airport operations or passenger enplanements.". Source - faa.gov/regulations_policies/handbooks_manuals/aviation/…. $\endgroup$ – RaajTram Apr 10 '16 at 3:31
  • $\begingroup$ Fair enough, I was distracted by your FAR citation. 91.215(b)(4) would be a better reference than 91.215(b)(5)(i). $\endgroup$ – NathanG Apr 10 '16 at 14:53

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