Welcome Guest. Sign in or Signup

2 Answers

ADS-B required under a class Charlie shelf?

Asked by: 4350 views , ,
FAA Regulations

We were having a discussion about ADS-B requirements in our local pilot forum last night. Maybe the experts here can find a definite answer to this:

Do you need to have ADS-B Out equipment to fly underneath the outer shelf of a class Charlie airspace?

Example: Let's fly across the Great Bay at 1000 MSL NE of Atlantic City.

FAR 91.225 (d) (3) can be read two ways:

  1. You need ADS-B Out when within the lateral boundaries of the Charlie, which would include anything inside the outer circle as projected to the ground, and you also need it when flying above the Charlie, or
  2. Only when both within the lateral boundaries and on top of the Charlie.

The FAA graphic suggests you don't need it under the shelf but I thought it would be worth getting an expert opinion on that.

Thank you guys!

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

2 Answers



  1. AV8R on Oct 01, 2020

    ADS-B is required wherever a transponder is required.

    Class A
    Class B (Including the 30 NM veil)
    Class C (If there is no 30 NM mode C veil then you can fly under Class C without ADS-B, Also if you overfly Class C up to 10,000 ft then you need ADS-B)
    Class E above 10,000 ft.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  2. John D Collins on Oct 02, 2020

    ADS-B is not required under the Class C shelf or a Class B shelf unless it is also inside the 30 NM mode C area. You may fly under the Atlantic City Class C shelf if you remain below 1300 MSL. You may not fly above a Class C shelf or Class B.unless you are ADS-B Out equipped. Where can you find a Class B shelf that you may fly under? Try KRHV to S74, stay below 8000 MSL. Also, you can base your aircraft at KRHV without equipping with ADS-B Out.

    The FAA choses its words carefully, most of the time. The regulation reads as:
    (3) 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;

    If they wanted to mean “below”, they would not need to have carved out “above” as they could have simply worded the regulation as:
    (3) Within the lateral boundaries of a Class B or Class C airspace area designated for an airport upward to 10,000 feet MSL;

    +2 Votes Thumb up 2 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.