These are present in the San Francisco class bravo / Oakland class charlie and O'Hare class bravo / Midway class charlie.




3 Answers 3


T is used to signify that the top of Class C airspace that lies under Class B is the bottom surface of that airspace. This is important when the Class C segment lies under multiple layers of Class B, where no single top altitude applies.

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  • $\begingroup$ So the T / 15 that I circled in blue in the north portion means that between 1500 and up to (but not including) 2100 feet MSL is the Oakland class charlie. And on the north side of that blue arc of the T / 15 is Oakland class charlie that begins at 1500' and goes up to (but not including) 3000 feet MSL? $\endgroup$
    – slantalpha
    Commented Jun 15, 2018 at 19:45
  • $\begingroup$ @jeff0000 Correct. T is particularly important when under multiple layers of Class B. $\endgroup$
    – Pilothead
    Commented Jun 15, 2018 at 20:25
  • $\begingroup$ An additional link is the official chart guide on faa.gov. Go to the 'VFR Terms' tab then the 'Controlled Airspace' section. $\endgroup$
    – user14897
    Commented Jun 15, 2018 at 21:10

You can start many "what does this thing on an FAA chart mean" questions with the FAA's Aeronautical Chart User's Guide. It doesn't go into a deep explanation, but does show it as an example in this case.

The symbol can be found on page 17 of the 2018 guide.

Airspace The figure at left identifies a sector that extends from the surface to the base of the Class B.


Since the Class C airspace is sandwiched between the surface and the shelves of the nearby Class B airspace, the T indicates that the upper limit of the ClassC surface area is on the bottom of the overhead Class B shelf.


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