C-DRONE GUIDE · 9 AUGUST 2026
Professional drone without a C class (legacy) in 2026: what it can still do, and when to upgrade your fleet
A professional operator who built their fleet before 2024 often discovers the constraint at the worst possible moment: while preparing a façade inspection in a town centre or a flyover of a building site near housing, they realise their aircraft, lacking a C0 to C6 class mark, may legally fly no closer than 150 m to any residential, commercial or industrial area. That is not an administrative footnote: it is the rule that, in 2026, rules out part of France's drone fleet from the most common urban missions by default. Here is what a "legacy" drone can still do, why the weight threshold exists, and how to decide whether to keep it, requalify it or replace it.
Published on 9 August 2026, reviewed on 10 August 2026 — regulations in force as of August 2026.
A "legacy" drone: what does that actually mean?
Delegated Regulation (EU) 2019/945 defines seven classes of unmanned aircraft, C0 to C6, each tied to a maximum mass, technical requirements (remote sensing, speed limitation, propeller guards depending on the class) and a remote identification module for classes C1 to C3 — our 2026 drone regulations guide covers every class and sub-category in full. The class is physically marked on the aircraft and backed by the manufacturer's declaration of conformity. Any drone placed on the market before 1 January 2024 and lacking that mark — nearly all of the professional fleet bought between 2016 and 2023 — is classed as "legacy" under articles 20 and 22 of Implementing Regulation (EU) 2019/947: no C class, none of the associated technical duties, but none of the leeway reserved for certified-compliant aircraft either.
Since 1 January 2026, the question has changed shape: the national scenarios S1, S2 and S3, which for years offered a parallel French route for flying certain missions near uninvolved people without a class mark, have been definitively withdrawn. France now applies exclusively the European framework — open, specific and certified categories — with no national safety net. A legacy drone that flew yesterday under an S3 declaration must now be reassessed strictly against the open category's European rules alone, or move to the specific category.
What an unclassed drone can still do in 2026
The open category remains available to a legacy drone, but on a binary logic based solely on take-off mass, battery included: below 250 g, the aircraft flies in sub-category A1 with no time limit, exactly like a C0 — our guide on under or over 250 g covers this case in detail. Above 250 g and up to 25 kg, however, the aircraft is permanently relegated to sub-category A3: no overflight of uninvolved people, and a minimum horizontal distance of 150 m from any residential, commercial, industrial or recreational area. That distance is not negotiable case by case within the open category; it applies regardless of the pilot's experience or the aircraft's actual condition.
| Legacy drone mass | Sub-category | Main constraint |
|---|---|---|
| < 250 g | A1 | No time limit, occasional overflight of isolated bystanders tolerated |
| 250 g – 25 kg | A3 (permanent) | 150 m minimum from residential, commercial, industrial or recreational areas |
In practice, an unmarked 700 g or 4 kg drone remains perfectly usable for agricultural mapping, quarry or forestry inspection, or filming an isolated industrial site far from any resident. It is no longer usable, however, for a façade inspection in a dense suburban area, construction monitoring in a town centre, or any flight close to occupied buildings: those missions, which make up a large share of a generalist professional pilot's activity, structurally fall outside the open category for an unclassed aircraft.
Why the 150 m threshold: human impact risk, not red tape
This threshold can feel arbitrary to an operator who knows their aircraft's real limits inside out, but it rests on a documented physical justification. The C0 to C6 classes and their associated distances were calibrated on ground-risk models that link a falling drone's mass and kinetic energy to the severity of the injuries it can cause. A landmark study led by Arterburn and co-authors for the US ASSURE research programme, published in 2017, reviewed over 300 works drawn from the automotive industry, toy standards and impact biomechanics to set injury-risk thresholds — blunt trauma, laceration, penetration — as a function of the energy transferred on impact (see the study on Google Scholar). That is precisely the kind of modelling behind the logic of the European regulation's mass thresholds: 250 g, 900 g, 4 kg and 25 kg are not commercial tiers, they are risk tiers.
More recently, a study by Svatý, Vrtal, Mičunek, Kohout, Nouzovský, Frydrýn, Blodek and Kocián, published in 2025 in PLOS ONE, used controlled impact tests to quantify how severely an unmanned aircraft strikes a human body depending on its mass and impact speed (see the study on Google Scholar). A drone classed C1 or C2 has undergone, at the manufacturer, tests and design features (propeller guards, speed limitation, frangibility) that lower this risk below a threshold accepted for flying near people; a legacy aircraft, even one that is technically comparable, has never gone through that standardised evaluation. Regulation therefore cannot presume it is safe, and defaults to the most conservative distance: 150 m, whatever the actual model.
Keep, requalify or replace your fleet: how to decide
The decision starts with the mission mix. An operator focused on agriculture, surveying large sites or inspecting isolated industrial facilities can keep their legacy drones for years to come: A3 suits them perfectly and no urgent replacement is warranted. Conversely, an operator whose business rests on façade inspections, urban construction monitoring or jobs in dense suburban areas has little durable alternative: investing in C1- or C2-marked aircraft, the only ones allowed to fly close to people in the open category, quickly pays for itself against the missions turned down or postponed for lack of compliant equipment.
A middle path remains, best reserved for occasional needs: flying a legacy drone under the specific category, using a standard scenario such as STS-01, covered in our open versus specific category guide, adding an external Remote ID module where required. That option lifts the 150 m constraint, but reintroduces, for every mission, a prior notification with ten working days' notice — a delay incompatible with recurring urban work, but entirely defensible for a rare urban job within a fleet otherwise geared to the open category. Before any purchase, the check to run is simple: the C class appears on the manufacturer's declaration of conformity and on the aircraft's label, never on the sales sheet alone — a point worth cross-checking against the insurance criteria covered in our professional liability insurance guide. A ground check, as our guide on drone penalties and inspections in France notes, verifies exactly this consistency between the declared class, the mission flown and the area overflown.
On the client side of a job in an urban area or near occupied buildings, the question to ask before signing becomes very concrete: does the provider have a C1- or C2-marked aircraft for this specific mission, or do they plan to fly an older drone under the specific category, with the ten-day notice that entails? A clear, immediate answer on this point is, like the FRA number or insurance, a good sign of a serious provider — request a quote stating how close your site is to uninvolved people, to get a proposal matched to the right regulatory framework.