Part 107 Visibility and Cloud Clearance: What §107.51 Requires

Most Part 107 pilots can recite "400 feet." Fewer can recite the weather minimums sitting right next to it. 14 CFR § 107.51 sets four operating limitations for every small UAS flight under Part 107: groundspeed, altitude, flight visibility, and distance from clouds. This explainer focuses on Part 107 visibility and cloud clearance, paragraphs (c) and (d), because those are the two that quietly decide whether a gray morning is legal to fly. Regulatory text was pulled from the eCFR on 7 Oct 2026. This is a rule explainer, not legal advice.

What § 107.51 says, in full

Under § 107.51, the remote pilot in command and the person manipulating the controls must comply with all of these:

• (a) Groundspeed may not exceed 87 knots (100 miles per hour).
• (b) Altitude cannot be higher than 400 feet above ground level, unless the aircraft is flown within a 400-foot radius of a structure and does not fly higher than 400 feet above the structure's immediate uppermost limit.
• (c) Minimum flight visibility, as observed from the location of the control station, must be no less than 3 statute miles.
• (d) Minimum distance from clouds must be no less than 500 feet below the cloud and 2,000 feet horizontally from the cloud.

That's the whole section. No exceptions are written into paragraphs (c) or (d) themselves.

Flight visibility is measured from where you stand

Paragraph (c) doesn't say "reported visibility" or "visibility at the nearest airport." It says visibility as observed from the location of the control station. The rule defines the term: flight visibility means "the average slant distance from the control station at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night."

In practice that means:

• An airport weather report can be a useful clue, but it doesn't settle the question. Valley fog, river haze, or smoke at your launch point can be worse than what the airport ten miles away is reporting, or better.
• You need to be able to pick out a prominent object roughly three statute miles away. If you can't, the flight doesn't meet § 107.51(c).
• At night, the test switches to prominent lighted objects. Night flying itself is governed by § 107.29, which adds anti-collision lighting and its own requirements on top of § 107.51.

Cloud clearance: 500 below, 2,000 horizontal

Paragraph (d) sets two separate distances, and both apply:

• 500 feet below the cloud. If the cloud base is 600 feet above the aircraft's location, the highest you can fly there is about 100 feet AGL, regardless of the 400-foot ceiling in paragraph (b).
• 2,000 feet horizontally from the cloud. Low scattered clouds or a fog bank drifting across a field count. You must keep 2,000 feet sideways from them, not just stay underneath.

The rule doesn't list any "above the clouds" option. Since you also have to keep the aircraft in visual line of sight under § 107.31, flying into or over a cloud layer isn't a workable Part 107 plan.

How § 107.51 ties into your preflight

§ 107.49(a) requires the remote pilot in command, before flight, to assess the operating environment, and that assessment must include local weather conditions. So the weather check isn't optional paperwork. It's how you show you looked at visibility and cloud bases before launching, and kept looking as conditions changed.

A simple field routine:

1. Check forecast and nearby reported ceilings and visibility before you drive.
2. On site, pick a prominent landmark about three statute miles out and confirm you can identify it from the control station.
3. Estimate the cloud base. If it's low, cap your planned altitude at 500 feet below it.
4. Watch for fog, low scud, and drifting cloud during the job, and land if you lose the margin.
5. Note the conditions in your flight log.

Can § 107.51 be waived?

Yes, in principle. § 107.205(i) lists § 107.51, "Operating limitations for small unmanned aircraft," among the regulations a certificate of waiver issued under § 107.200 may authorize deviation from. A waiver is a written FAA approval with its own conditions, and the applicant has to show the operation can be done safely. Our Part 107 waiver basics explainer walks through how that process works. Without a waiver in hand, the minimums above apply.

Airspace authorization doesn't change the weather minimums

A LAANC authorization or other airspace approval under § 107.41 answers a different question: whether you can fly in that controlled airspace at all, and up to what altitude. It doesn't relax § 107.51. A LAANC grid altitude of 400 feet still drops to about 100 feet AGL under a 600-foot cloud base, because paragraph (d) keeps you 500 feet below it.

Common mistakes

• Treating the airport report as the answer. The rule measures from your control station.
• Forgetting the horizontal 2,000 feet. Staying under a cloud isn't enough if a cloud is nearby at your altitude.
• Using a visual observer as a workaround. A visual observer helps with see-and-avoid. The visibility rule is still measured from the control station.
• Not logging it. If conditions are marginal, write down what you observed and why you flew, or why you didn't.

The bottom line

§ 107.51(c) and (d) are short: 3 statute miles of flight visibility from the control station, 500 feet below clouds, and 2,000 feet horizontally from them. They apply to every Part 107 flight unless you hold a waiver that says otherwise. Confirm the current text on the eCFR before relying on it, and talk to an aviation attorney if a specific operation is in question. If you run a drone business and want flight logs, jobs, and client records in one place, Pilot Ledger is built for that.