1.3 Operating Rules Overview (Subpart B)
Key Takeaways
- Maximum altitude is 400 ft AGL, or up to 400 ft above a structure if within a 400-ft radius of it.
- Maximum groundspeed is 100 mph (87 knots); minimum visibility is 3 statute miles from the control station.
- Cloud clearance is 500 ft below and 2,000 ft horizontal from clouds at all times.
- Only one Remote PIC at a time; small UAS must yield right of way to ALL other aircraft, with no exceptions.
- Visual line of sight must be maintained unaided except for corrective lenses; the 8-hour bottle-to-throttle and 0.04% BAC rules apply.
Core Operating Rules
Subpart B (sections 107.11 to 107.51) contains the limits you will fly by every day and the numbers the UAG exam tests most. Burn the table at the bottom into memory.
Remote PIC Authority (Section 107.19)
The Remote PIC has final authority and responsibility for the operation and safety of the flight. One Remote PIC is designated before each flight; the role may transfer in flight only with a clear, acknowledged handoff. The Remote PIC may let an uncertificated person manipulate the controls under direct supervision, but must be able to take immediate control at any moment.
Visual Line of Sight (Section 107.31)
The Remote PIC, the person manipulating the controls, or the visual observer must keep the aircraft in sight with vision unaided by any device other than corrective lenses throughout the flight, and must always know the aircraft's location, attitude, altitude, and direction of flight plus the surrounding airspace.
| Aid | Allowed for VLOS? |
|---|---|
| Prescription glasses or contacts | Yes |
| Binoculars / spotting scope | No (only for brief scanning, not as primary VLOS) |
| First-person-view (FPV) goggles alone | No — a VO or the Remote PIC must keep unaided VLOS |
| Onboard camera feed as sole tracking | No |
Visual Observer (Section 107.33)
A VO is optional. When used, the VO must see the aircraft unaided, scan for hazards, and stay in direct communication with the Remote PIC. A VO may not manipulate the flight controls.
Yielding Right of Way (Section 107.37)
A small UAS must yield the right of way to all other aircraft — manned aircraft, other UAS with right of way, airborne vehicles, and launch/reentry vehicles. It may not pass over, under, or ahead of another aircraft unless well clear. There are no exceptions — the drone always gives way.
The Numbers (Section 107.51 and related)
| Rule | Requirement | Section |
|---|---|---|
| Maximum altitude | 400 ft AGL, or within 400 ft of a structure | 107.51 |
| Maximum groundspeed | 100 mph (87 knots) | 107.51 |
| Minimum visibility | 3 statute miles from the control station | 107.51 |
| Cloud clearance | 500 ft below, 2,000 ft horizontal | 107.51 |
| One pilot, one aircraft | No multi-aircraft control unless waived | 107.35 |
| Visual line of sight | Required at all times | 107.31 |
| Careless/reckless ops | Prohibited | 107.23 |
| Hazardous-operation drops | No dropping objects that create a hazard | 107.23 |
| Drugs/alcohol | 8-hour bottle-to-throttle, 0.04% BAC | 107.27 |
The Altitude Exception, Worked
The 400 ft AGL ceiling rises near tall structures: within a 400-foot radius of a structure you may fly up to 400 feet above the structure's highest point.
Worked example: A cell tower is 300 ft tall. Stay within 400 ft horizontally of it and you may climb to 700 ft AGL (300 + 400). Move 500 ft away laterally and your ceiling snaps back to 400 ft AGL.
Careless or Reckless Operation (Section 107.23)
No person may operate a small UAS so as to endanger life or property, and no person may drop an object in a manner that creates a hazard. This catch-all lets the FAA act against unsafe flying even when no specific numeric limit was broken.
Alcohol and Drugs (Section 107.27)
Remote pilots follow the same substance rules as manned pilots: no alcohol within 8 hours of flying ("bottle to throttle"), blood alcohol below 0.04%, no flying while impaired by any drug (including drowsy-making over-the-counter medication), and you cannot refuse an FAA-requested test.
Applying the Operating Limits in Scenarios
The operating limits in Subpart B are most often tested as scenarios, not as bare recall. The skill is translating a described situation into the right number and the right section. Below are the patterns the UAG exam reuses.
Visibility and Cloud Clearance Together
Visibility (3 statute miles) and cloud clearance (500 ft below, 2,000 ft horizontal) are measured from the control station / the aircraft's position, and both must be satisfied at once. A question may state a 4-statute-mile visibility but place a broken cloud layer 300 ft above the planned altitude — that fails the 500-ft-below rule even though visibility is fine. Always check both conditions before declaring a flight legal. A useful mnemonic for the cloud numbers: 5 below, 2 thousand to the side.
Speed: Groundspeed, Not Airspeed
The 100 mph (87 knot) limit is groundspeed. A 70 mph drone flying with a 35 mph tailwind can reach 105 mph over the ground and would violate the limit even though its airspeed is well within design specs. Conversely, fighting a strong headwind reduces groundspeed. This is a favorite trick: a question gives airspeed plus a wind component and expects you to compute groundspeed and compare it to 100 mph.
Yielding and See-and-Avoid
The yield rule (Section 107.37) is absolute and pairs with the broader duty to see and avoid. If a manned aircraft appears, the drone must give way by descending, landing, or maneuvering clear — the manned aircraft is never expected to maneuver around a drone. Scenario stems describe a crop-duster, a medevac helicopter, or a hot-air balloon entering the area; the correct response is always that the drone yields immediately.
Operating From Moving Vehicles (Section 107.25)
| Condition | Allowed? |
|---|---|
| Flying from a moving car over a sparsely populated area | Yes |
| Flying from a moving vehicle over a densely populated area | No |
| Carrying property of another for compensation from a moving vehicle | No |
| Operating over people while moving | No (use Subpart D rules, not 107.25) |
Putting It Together — Worked Scenario
You plan a flight at 350 ft AGL in Class G airspace. Visibility is 5 SM. A scattered cloud deck sits at 700 ft. Wind is calm and your aircraft cruises at 40 mph. Is this legal? Altitude (350 < 400): fine. Visibility (5 > 3): fine. Cloud clearance: 700 - 350 = 350 ft below the clouds, which is less than the required 500 ft — so the flight as planned is illegal. Lower the operating altitude to 200 ft AGL and you gain 500 ft of clearance below the 700-ft deck, restoring compliance. This single example exercises altitude, visibility, and cloud clearance simultaneously, exactly the way the exam layers the rules.
What is the maximum altitude for a small UAS in open airspace not near a structure?
A 300-foot cell tower stands in an open field. While inspecting it within 200 feet horizontally, the highest you may legally fly is:
Under Part 107, the minimum flight visibility from the control station is:
A small UAS must yield the right of way to:
Which cloud clearance must a small UAS maintain under Part 107?