Regulations
How High Can a Drone Legally Fly?
Four hundred feet, with one exception that is more useful than most people realize and narrower than most people assume.
Key takeaway
400 feet above ground level, unless you are within a 400-foot radius of a structure — then 400 feet above that structure's uppermost limit. Both conditions must be met, not either one.
400 feet above ground level. That is the ceiling for a small unmanned aircraft under 14 CFR 107.51(b), and it is the number most people already know.
The part worth knowing is the exception, because it is the difference between being able to inspect a 300-foot tower and not.
The rule, exactly as written
Section 107.51(b) says the altitude of the aircraft cannot be higher than 400 feet AGL 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
Note the "and." Both conditions apply together. This is not a choice between two allowances.
So for a 200-foot tower, staying inside a 400-foot radius of it, your ceiling becomes 600 feet — the structure's 200 feet plus 400. Step outside that radius and you are back to 400 feet AGL immediately, mid-flight, with no transition.
The phrase "immediate uppermost limit" means the top of the structure itself. Not the top of the hill it sits on, not the top of the tallest thing on the site. If a 60-foot building has a 15-foot antenna on the roof, the uppermost limit is 75 feet and the ceiling is 475.
What counts as a structure
The regulation does not define it, which is deliberate. In practice it means a fixed, man-made object: buildings, towers, bridges, cranes, wind turbines, silos, stacks. A hill is not a structure. Neither is a tree, and neither is a moored balloon.
The exception exists so that infrastructure inspection is possible. Reading it as general permission to gain altitude near any tall object is not what it says.
Above ground level, not above sea level
Four hundred feet AGL means 400 feet above the terrain beneath the aircraft, not 400 feet above your launch point.
Fly from the base of a hill out over rising ground and your height above the surface decreases without you doing anything — but so does your legal headroom, because the limit tracks the terrain. Fly out over a valley and the aircraft is higher above the ground than the controller says, because most flight controllers report height relative to the takeoff point.
This is a real trap in hilly terrain. Your app is telling you a number relative to where you launched; the regulation is asking about the ground directly below.
Sectional charts give terrain elevation and maximum elevation figures — the large sparse digits printed across each quadrangle, in thousands and hundreds of feet MSL — which is how you check what is underneath you before you fly there.
The other three limits in the same section
Altitude is one of four operating limitations in 107.51. The exam treats them as a set, and so should you.
| Limit | Figure |
|---|---|
| Maximum groundspeed | 87 knots (100 mph) |
| Maximum altitude | 400 ft AGL, or 400 ft above a structure within a 400-ft radius |
| Minimum flight visibility | 3 statute miles, from the control station |
| Minimum distance from clouds | 500 ft below, 2,000 ft horizontally |
Groundspeed, not airspeed. 87 knots is measured over the ground, which means a tailwind counts against you. A 60-knot aircraft in a 30-knot tailwind is over the limit while its airspeed indicator reads perfectly legal.
There is no minimum altitude. Nothing in Part 107 sets a floor. You may fly at 10 feet if the operation is otherwise safe and lawful — subject to 107.19's requirement that the remote pilot in command ensures the operation poses no undue hazard, and 107.23's prohibition on careless or reckless operation.
For the visibility and cloud figures, see VFR weather minimums — those numbers differ from the Part 91 table pilots learn, and the difference is a common exam trap.
The one that is not in Part 107 at all
There is no federal minimum altitude over private property, and no federal rule prohibiting flying over someone's house. Trespass and privacy are matters of state and local law, and they vary enormously.
What Part 107 does regulate is flying over people, which is a separate framework entirely — the four categories in subpart D, based on the aircraft's certification rather than your altitude. Flying at 350 feet over a crowd is not made legal by being under 400 feet.
Why 400 feet, and not some other number
The figure is not arbitrary. Manned aircraft operating under 14 CFR 91.119 must generally stay at least 500 feet above the surface away from congested areas, and 1,000 feet above the highest obstacle within 2,000 feet horizontally over a congested area.
Four hundred feet leaves a 100-foot buffer beneath the lowest altitude at which manned traffic is normally expected. That is the entire logic, and it is also why the structure exception is bounded by a radius: near a tall structure, manned traffic is already keeping clear of the structure itself, so the drone can occupy the space around it without eroding the same separation.
Knowing the reason makes the rule harder to misremember, and it explains why helicopters and agricultural aircraft — which are lawfully exempt from those minimums — turn up at drone altitude without warning.
Can you get a waiver to fly higher?
Yes. Section 107.51 appears in the list of waivable regulations at 14 CFR 107.205, so the FAA can authorize a deviation from the altitude limit.
Two things to be realistic about:
- A waiver is not an authorization. If the higher altitude is also in controlled airspace, you need both, and both are applied for through FAA DroneZone rather than through a LAANC app.
- Successful applications describe mitigations, not needs. "The client wants a higher shot" is not a case. A defined operating area, an observer positioned to see approaching traffic, a hard ceiling, coordination with a nearby facility, and a lost-link procedure that descends rather than climbs — that is a case.
Frequently asked questions
How high can a drone legally fly in the US?
400 feet above ground level under 14 CFR 107.51(b). The exception is that within a 400-foot radius of a structure, you may fly up to 400 feet above that structure's uppermost limit, which allows tall-structure inspection.
Is the 400-foot limit above ground or above sea level?
Above ground level, measured from the terrain directly beneath the aircraft. Because most flight controllers display height relative to the takeoff point, flying over rising or falling ground changes your true AGL height without the displayed figure changing.
Can I fly higher than 400 feet near a tall building?
Yes, within a 400-foot radius of the structure and no higher than 400 feet above its uppermost limit. Both conditions apply together, so leaving the 400-foot radius returns you to the 400-foot AGL ceiling immediately.
Is there a minimum altitude for drones?
No. Part 107 sets no minimum altitude. The operation must still avoid creating an undue hazard under 14 CFR 107.19 and must not be careless or reckless under 107.23.
What is the maximum speed for a drone under Part 107?
87 knots, which is 100 miles per hour, measured as groundspeed. Because it is groundspeed rather than airspeed, a strong tailwind can put an aircraft over the limit while its indicated airspeed remains well below it.
Can you get a waiver to fly above 400 feet?
Yes. Section 107.51 is waivable under 14 CFR 107.205. A successful application describes specific mitigations such as a bounded operating area, dedicated observers and a descending lost-link procedure. If the operation is also in controlled airspace, a separate airspace authorization is required.
The four numbers in 107.51 are among the most heavily tested facts on the exam, and Regulations is now 48 percent of it. Check yourself with the free readiness assessment.
Sources
Put this guide into practice.
Take the free assessment to see how this topic fits into your current exam readiness.
Start free practice