What is Section 107.51 (operating limits)?
14 CFR § 107.51 sets the operating limits for Part 107 drone flight: maximum 100 mph groundspeed, 400 ft AGL altitude, 3 statute mile visibility, and minimum 500 ft below clouds, 2,000 ft horizontal from clouds.
§ 107.51 codifies the basic operating envelope:
• Groundspeed: maximum 100 mph (87 kts). • Altitude: maximum 400 ft AGL, except within 400 ft of a structure (then up to 400 ft above the structure's highest point). • Visibility: minimum 3 statute miles from the control station. • Cloud clearance: minimum 500 ft below clouds, 2,000 ft horizontal from clouds.
These limits can be waived under § 107.205 with an individual FAA waiver — common waivers include altitude waivers for tower inspection, visibility waivers for poor-weather operations, and night-operation waivers (now obsolete since the 2021 night rule update).
Visibility and cloud clearance are enforced as 'as observed by the remote pilot at the control station' — drone pilots aren't required to file weather briefings but must observe conditions before and during flight.
What this means for pilots
The 400 ft AGL limit is well-known but easy to violate near tall structures (you can go higher within 400 ft horizontally of them). Visibility and cloud clearance are often missed — flying with low ceilings or in haze can technically violate § 107.51 even if airspace is clear.
FAQ
Can I fly above 400 ft AGL?
Only within 400 ft horizontally of a structure (up to 400 ft above its top). Otherwise no, except with a waiver.
What if visibility is exactly 3 miles?
Marginal — 3 miles is the minimum. Pilots typically apply a safety margin. If you can't see 3 miles, do not fly.
Do these limits apply at night?
Yes. The 2021 night rule allowed Part 107 operation at civil twilight and at night with anti-collision lighting; the operating limits remain.
Related terms
FAA regulations change. Verify current rules at faa.gov/uas before relying on this article for flight planning. Altoa is not the FAA.