You generally cannot fly in Class C airspace without ADS-B Out. Federal rules require the equipment inside Class C, and they extend the same requirement to the airspace above Class C, within its lateral boundaries, all the way up to 10,000 feet MSL. If your aircraft is not equipped, your only legal path in or over that airspace is a deviation authorization from air traffic control, requested in advance through the FAA’s ADAPT tool.
What the Rule Actually Covers
Under 14 CFR 91.225(d)(3), ADS-B Out is required inside Class C airspace and above the ceiling of any Class C area, within its lateral boundaries, up to 10,000 feet MSL.1eCFR. 14 CFR 91.225 – Automatic Dependent Surveillance-Broadcast (ADS-B) Out Equipment and Use That second half catches a lot of pilots. If a Class C shelf tops out at 4,000 feet above the airport, the column of airspace from that ceiling up to 10,000 feet MSL still counts. Climbing a few hundred feet above the charted top does not put you in the clear.
Trying to overfly higher than 10,000 feet MSL runs into a separate rule. ADS-B Out is independently required in Class E airspace at and above 10,000 feet MSL across the contiguous United States, except within 2,500 feet of the surface.1eCFR. 14 CFR 91.225 – Automatic Dependent Surveillance-Broadcast (ADS-B) Out Equipment and Use There is no altitude that lets an unequipped aircraft cross Class C without either the equipment or ATC permission.
Requesting a Deviation Through ADAPT
The realistic option for an unequipped aircraft is the ADS-B Deviation Authorization Preflight Tool, or ADAPT. The FAA built it specifically for pilots who need to operate in ADS-B airspace without the equipment working.2Federal Aviation Administration. ADS-B Deviation Authorization Preflight Tool
Every ADAPT request has to meet three conditions:
- The aircraft must have an operational transponder with Mode C altitude reporting, even though ADS-B Out is missing or inoperative.
- The request must be submitted no more than 24 hours and no less than 1 hour before the proposed departure time.
- If you don’t depart within 2 hours of the proposed departure time, the authorization cancels automatically.
The FAA treats a failed installation differently from no installation at all. If your ADS-B Out equipment is installed but broken, you can request a deviation at any time to continue to your destination or reach a repair shop. If your aircraft was never equipped, the one-hour advance minimum applies.3Federal Aviation Administration. Air Carrier Inoperative ADS-B Authorized Deviation Request Process
Approval is not guaranteed. ATC can deny a request based on workload, radar status, or traffic. Busy airports are less likely to approve deviations, and the FAA tracks requests by tail number, so repeated requests for the same aircraft may draw more scrutiny. Approval and denial emails don’t include reasons.
The Narrow Exceptions That Do Not Help Most Pilots
A handful of exceptions exist in the regulation, but none of them opens Class C to a typical general aviation airplane without ADS-B Out.
Aircraft never certificated with an engine-driven electrical system, and never retrofitted with one, get some relief. This mostly covers gliders and balloons. Even those aircraft can only fly without ADS-B Out if they stay outside the lateral boundaries of any Class B or Class C airspace and remain below its ceiling (or below 10,000 feet MSL, whichever is lower).1eCFR. 14 CFR 91.225 – Automatic Dependent Surveillance-Broadcast (ADS-B) Out Equipment and Use The exemption specifically does not let them enter or overfly Class C.
Certain government operations related to national defense, homeland security, intelligence, or law enforcement can be authorized to operate with ADS-B turned off when a broadcast would compromise the mission. These are regulatory allowances for specific agencies, not something available to a civilian pilot.
What ADS-B Out Doesn’t Replace
An ADAPT approval only waives the ADS-B Out requirement. Other equipment and communication rules still apply.
Under 14 CFR 91.215, any aircraft operating in Class A, Class B, or Class C airspace needs a working transponder with Mode C altitude reporting.4eCFR. 14 CFR 91.215 – ATC Transponder and Altitude Reporting Equipment and Use ADAPT itself lists an operational Mode C transponder as a prerequisite, so a deviation for ADS-B Out doesn’t help you if your transponder is also out.2Federal Aviation Administration. ADS-B Deviation Authorization Preflight Tool
Under 14 CFR 91.130, every aircraft operating in Class C must establish two-way radio communication with ATC before entering and maintain it while inside.5eCFR. 14 CFR 91.130 – Operations in Class C Airspace That applies whether you’re landing, transiting, or flying above the airport within the lateral boundaries. No radio means no Class C entry, regardless of what your ADS-B situation looks like.
What Happens If You Fly Without Equipment or Authorization
Operating in ADS-B-required airspace without the equipment and without an authorization is a regulatory violation. The FAA has stated it conducts post-flight analysis to verify equipment compliance and assess operator intent, so an unequipped flight through Class C is likely to be noticed.6Federal Aviation Administration. ADS-B Compliance and Enforcement for Foreign Operators Enforcement can range from warning letters to civil penalties or certificate suspension, depending on the facts and the pilot’s history. Under the FAA’s compliance philosophy, a first-time inadvertent entry may draw counseling rather than a penalty, but deliberate or repeated violations tend to be handled more severely.
The short version for planning: if your airplane doesn’t have ADS-B Out, treat Class C and the airspace above it as closed to you unless you have an ADAPT authorization in hand, a working transponder with Mode C, and two-way radio contact with ATC.