Here is a proposal that sounds unimprovable. You fly commercially near an airport. Manned traffic cannot see you. So you fit your aircraft with ADS-B Out, start broadcasting your position, and every aircraft with a receiver — plus air traffic control — knows exactly where you are.
It is illegal. Not discouraged, not a grey area. Two sections of Part 107 prohibit it outright, and almost nobody preparing for the exam has read them.
§ 107.52, in full: "Unless otherwise authorized by the Administrator, no person may operate a small unmanned aircraft system under this part with a transponder on."
§ 107.53, in full: "Unless otherwise authorized by the Administrator, no person may operate a small unmanned aircraft system under this part with ADS-B Out equipment in transmit mode."
Both were added by the same amendment in January 2021 — the rulemaking most people remember for night operations and flying over people. These two sections arrived in the same package and got almost none of the attention.
Why forbid the thing that makes you visible?
Because the system it feeds has a finite capacity, and drones are numerous.
ADS-B and transponder returns are consumed by air traffic control displays and by collision-avoidance systems in manned aircraft. Those systems were designed around a population of manned aircraft. Add a large number of low, slow, small unmanned aircraft all broadcasting, and you degrade the picture for everyone: cluttered controller displays, and traffic alerts firing constantly in cockpits for aircraft that pose no real conflict. An alert that fires too often gets ignored, which is worse than no alert.
So the FAA's answer is that the sky below 400 feet is not where that infrastructure should be spent. Your separation from manned traffic comes from other things entirely: staying below 400 feet, keeping the aircraft in visual line of sight, yielding right of way, and getting airspace authorisation before you enter controlled airspace so that ATC knows the operation exists.
Read the verbs — this is narrower than it sounds
Neither section prohibits owning, fitting or carrying the equipment. Both prohibit a state of operation.
| Situation | Permitted under Part 107? |
|---|---|
| Transponder installed, switched off | Yes — the prohibition is on operating "with a transponder on" |
| Transponder installed and on | No |
| ADS-B In — receiving traffic, not transmitting | Yes. Only transmit mode is prohibited |
| ADS-B Out installed but not transmitting | Yes — the trigger is "in transmit mode" |
| ADS-B Out transmitting | No |
That distinction is not pedantry. ADS-B In is genuinely useful — it lets you see manned traffic approaching your operating area, which supports the see-and-avoid duty that Part 107 does place on you. Receiving is encouraged by the logic of the rule. Transmitting is what fills up somebody else's screen.
Aircraft that ship with ADS-B In as a safety feature are not putting you in breach. Check whether a system you are buying transmits, receives, or does both, and know which mode it is in.
The exception, and why it is not a waiver
Both sections open with the same five words: "Unless otherwise authorized by the Administrator." That is the entire escape route, and it is worth being precise about what it is not.
It is not an ATC clearance. Being cleared into Class D does not authorise you to switch a transponder on.
And it is not a waiver. Neither § 107.52 nor § 107.53 appears in § 107.205, the closed list of ten sections the FAA will consider waiving — so there is no waiver application for this. As we set out in our guide to what the FAA will and will not waive, if a rule is not on that list, the waiver simply does not exist. What the text points to instead is authorisation from the Administrator, which is a different instrument.
The practical read. If you are a normal Part 107 operator, treat these two sections as absolute. Turn it off, or fly something that does not transmit. The authorisation route exists for operations whose circumstances justify it — and if yours are those circumstances, you are already talking to the FAA about a good deal more than this.
Where this shows up in real life
Repurposed manned-aviation equipment. Experimenters fitting general-aviation avionics to a large multirotor are the most likely people to trip over this without noticing.
Aircraft marketed on "full airspace awareness." Read the specification. Awareness usually means ADS-B In, which is fine. If it transmits, it is not fine under Part 107 as written.
Anyone reasoning from first principles. This is the trap. The rule runs against the intuition that more information is always safer, so people who think it through without reading it reach the wrong answer confidently. That is exactly why it is examinable.
Part 108, eventually. The proposed BVLOS rule leans heavily on electronic conspicuity and would work differently — but it is not law, and until it is, Part 107 says what it says.
What we could not confirm
- We could not confirm what an application for authorisation under these sections looks like, who processes it, or how long it takes. The regulation names no form and no portal, and we found no FAA page describing the process.
- We could not confirm how often such authorisations are granted or for what kinds of operation.
- We could not confirm the FAA's own reasoning for the prohibition from the regulatory text itself, which states the rule without explaining it. The frequency-congestion rationale above is the widely understood basis and is our summary, not an FAA quotation.
- We could not confirm how these sections interact with an aircraft whose ADS-B Out cannot be disabled by the operator. If that describes yours, the question belongs with the FAA's UAS Support Center before the flight, not after.
- Text verified against the eCFR edition current to 12 August 2026. Both sections were added by Amdt. 107-7, 86 FR 4513, 15 January 2021.
The short version
You may not operate under Part 107 with a transponder on, and you may not operate with ADS-B Out in transmit mode. Installing the equipment is not the offence — transmitting is. ADS-B In, which receives traffic rather than announcing you, remains available and is genuinely useful. The only way out is authorisation from the Administrator, and because neither section sits on the § 107.205 list, a waiver is not on the table. The intuition that broadcasting your position must be safer is the reason people get this wrong, and it is precisely why the exam asks.
These two sections are short, easy marks, and routinely skipped in study material written before 2021. Start free with the Flycensed iOS app and its 485+ practice questions, or work through the regulations chapters in the Part 107 Complete Study Guide ($14.99).
See and be seen
Affiliate links — we may earn a commission from purchases at no extra cost to you. We only list gear we would actually put on a job.
- Athlon Optics 8x42 Midas UHD Binoculars — If you cannot broadcast your position, spotting manned traffic early is the mitigation you actually have. A visual observer with glass is worth more than any avionics you are not allowed to switch on.
- JKSafety Licenced Drone Pilot Reflective Safety Vest (JK100FAA) — Your own conspicuity on the ground is not regulated and is entirely your problem; a marked vest also stops most of the conversations before they start.
- VIFLY Drone Strobe Light — Visual conspicuity is permitted and, for night work under 107.29, required. This is the kind of visibility Part 107 wants from you.