One of the most commonly misunderstood areas of Part 107 involves flying small unmanned aircraft systems (sUAS) over moving vehicles. Whether you're filming a highway, tracking a car for a commercial production, or conducting infrastructure surveys near busy roads, the rules governing flight over moving vehicles are critical to understand before your FAA knowledge test — and before you ever launch a drone near traffic. The 2021 rewrite of Part 107 (effective April 21, 2021) significantly updated these rules, replacing broad blanket prohibitions with a nuanced, category-based framework that allows some operations over moving vehicles without a waiver, while others remain tightly restricted.
This article walks through the full framework: what the rules actually say, how the operational categories work, when waivers are required, and the key distinctions the FAA knowledge test loves to probe. Understanding both the letter and the intent of these rules will help you operate safely and legally — and ace the exam.
The Core Prohibition and Why It Exists
The foundational safety concern behind restrictions on flight over moving vehicles is third-party risk. If a drone experiences a malfunction, loses signal, or is flown negligently, it may fall onto a vehicle below. A drone striking a moving car at highway speed can cause serious injury or a fatal accident. Unlike a person on the ground who might see a drone and move away, a driver's ability to react is severely limited. This risk to uninvolved people — who have given no consent to be below a drone — is precisely why the FAA treats flight over moving vehicles as a distinct and elevated hazard.
Prior to the 2021 rule update, Part 107 generally prohibited flight over moving vehicles in densely populated areas and any flight over people who were not directly participating in the operation. The 2021 revision restructured these rules by tying the permissions to specific operational categories based on drone weight, design features, and the presence of risk-mitigating technology.
How the Category System Works
Under the updated 14 CFR Part 107, operations over human beings and moving vehicles are governed by four operational categories. Each category has progressively stricter requirements, and the rules for moving vehicles track closely with — but are not identical to — the rules for flying over people. Under §107.145, the rules governing moving vehicles turn on whether the flight is sustained over the vehicle versus merely transient, and on whether the operating site is closed or access-restricted — not on a distinction between congested and non-congested areas.
Category 1: Lightweight Drones with No Exposed Rotating Parts
A drone qualifies for Category 1 operations if it weighs 0.55 pounds (250 grams) or less at takeoff, including everything on board. There must be no exposed rotating parts that would lacerate human skin on contact. Under §107.145, a Category 1 drone may not be operated over moving vehicles unless the operation occurs within or over a closed- or restricted-access site and the remote pilot ensures that no vehicle is beneath the aircraft, or the flight over a moving vehicle is only transient rather than sustained. The key practical point: a sub-250-gram drone gives you the most operational flexibility, but it does not give you unlimited access to fly over traffic anywhere you choose.
Category 2: FAA-Accepted Means of Compliance
Category 2 allows flight over moving vehicles when the drone has been designed and declared to meet an FAA-accepted Means of Compliance (MOC) for limiting injury severity. Specifically, the drone must not be capable of causing injury equivalent to a transfer of more than 11 foot-pounds of kinetic energy upon impact with a human being. The drone must also have no exposed rotating parts that could lacerate, and it must not be operating under a safety deficiency. Under §107.145, sustained operations over moving vehicles are still permitted only within or over a closed- or restricted-access site where the remote pilot ensures that all human beings located inside a moving vehicle are on notice, or where the flight otherwise meets the conditions specified in the rule — there is no general congested/non-congested distinction for Category 2.
Category 3: Higher Kinetic Energy Threshold, Restricted Access
Category 3 drones meet a higher kinetic energy threshold — up to 25 foot-pounds — but because the potential injury severity is greater, operations over moving vehicles are significantly more restricted. A Category 3 drone may fly over moving vehicles only when:
- The operation takes place within a controlled or restricted-access site, and the remote pilot has ensured that no unauthorized people are present in or near the operating area; or
- The moving vehicles are within a location where access by people who are not participants in the operation is restricted by a physical barrier or legal control (such as a closed road, a private lot, or a filming location secured by production personnel).
In other words, Category 3 operations over moving vehicles require that the vehicles themselves be in an environment where uninvolved people are effectively excluded. You cannot legally fly a Category 3 drone over a public highway with regular traffic under normal circumstances.
Category 4: FAA Airworthiness Certificate Required
Category 4 is the most demanding. These drones must hold an FAA airworthiness certificate, must be operated in accordance with the operating limitations in that certificate, and the remote pilot must follow any additional conditions it specifies. Category 4 can permit flight over moving vehicles, but the requirements imposed by the airworthiness certificate govern exactly what is and is not allowed.
Sustained Flight vs. Transient Overflight
The FAA draws an important distinction between sustained flight over moving vehicles and transient overflight. A transient overflight occurs when a drone briefly crosses over a vehicle or roadway during a flight that is otherwise not focused on hovering or loitering above traffic. Sustained flight means deliberately and continuously flying above moving vehicles — the type of flight involved in traffic monitoring, car chases for film, or road corridor surveys. This sustained-versus-transient distinction, combined with site-control requirements under §107.145, is the actual legal basis for restricting flight over moving vehicles — not whether the area is congested or non-congested. Remote pilots should be aware that even incidental, momentary crossings of roads with traffic should be minimized and planned carefully.
Waivers for Operations Not Meeting Category Requirements
If your drone or your intended operation does not fit neatly into one of the four categories — or if you want to conduct sustained operations over moving vehicles in a way that Category 1 through 4 would not otherwise permit — you must apply for a Part 107 waiver through the FAA's DroneZone portal. Waivers require a detailed safety case demonstrating that your operation can be conducted at an equivalent level of safety. The FAA reviews the specific risk mitigations you propose, such as use of a safety pilot, chase vehicles, traffic control, geofencing, parachute systems, or operational time restrictions. Waivers are not guaranteed, and the FAA may take weeks or months to process them. Planning ahead is essential.
Why It Matters in Practice
Understanding these rules matters for real-world operations in several concrete ways. A commercial drone operator filming a car commercial on a closed track has a clear path: secure the site, restrict access, and operate under Category 3. A real estate photographer whose sub-250-gram drone only transiently crosses a residential street in a quiet neighborhood faces minimal regulatory burden under Category 1. But a pilot who launches a 1.5-pound drone to hover over a busy freeway interchange without a waiver is in clear violation of Part 107 — and risks not just FAA enforcement, but criminal liability if an incident occurs.
Operators must also remember that Part 107's moving vehicle rules do not supersede other applicable rules. You must still comply with airspace authorizations, remote ID requirements, visual line of sight requirements, and daylight or twilight operating restrictions. A waiver for flight over moving vehicles does not automatically grant permission to fly in controlled airspace.
Key Numbers and Rules
- 0.55 lbs (250 g) or less: Weight threshold for Category 1 — the most permissive category for over-vehicle operations, subject to the sustained-flight and site-control conditions of §107.145.
- 11 ft-lbs kinetic energy: Maximum impact energy for Category 2 drone classification.
- 25 ft-lbs kinetic energy: Maximum impact energy for Category 3 drone classification.
- Category 3 over moving vehicles: Requires controlled/restricted-access site with unauthorized persons excluded.
- Category 4: Requires FAA airworthiness certificate; operating limitations in the certificate control what is permitted.
- Waivers: Available through FAA DroneZone for operations outside category permissions; must demonstrate equivalent level of safety.
- Effective date of updated rules: April 21, 2021 (the BEYOND visual line of sight and operations over people final rule).
Common Test Traps
- Assuming sub-250g means fly anywhere over traffic: Category 1 (sub-250g) allows transient flight over moving vehicles or flight over vehicles within a closed/restricted-access site, but does NOT automatically permit sustained flight over moving vehicles outside those conditions. Know the distinction — it's based on sustained vs. transient flight and site control, not congested vs. non-congested areas.
- Confusing Category 2 and Category 3 kinetic energy thresholds: Category 2 is 11 ft-lbs; Category 3 is 25 ft-lbs. Mixing these up on the exam is a common error.
- Forgetting the site-control requirement for Category 3: Category 3 over moving vehicles requires the location to be restricted so uninvolved people cannot be present — a public road with normal traffic does not qualify.
- Thinking a waiver covers everything: A waiver for flight over moving vehicles is specific to that operation and does not grant blanket permission for all Part 107 restrictions — other rules still apply independently.
- Conflating rules for flight over people with rules for moving vehicles: While closely related, the categories for over-people operations and over-moving-vehicle operations have nuances. Read each set of rules carefully rather than assuming they are identical in all respects.