Sub-250g Drone C0 Class Marking in the UK

What the C0 Class Marking Actually Means

The C0 class marking is part of the classification system introduced under Commission Delegated Regulation (EU) 2019/945 as retained in UK law. This system assigns class markings from C0 through C6 to drones based on their weight, capabilities, and intended use. Each class marking corresponds to a set of technical requirements that the drone must meet at the point of manufacture.

For a drone to receive a C0 class marking, the manufacturer must demonstrate that the product meets the following technical requirements:

• Maximum Take-Off Mass below 250g, including payload
• Maximum speed in level flight of less than 19 metres per second
• Maximum attainable height above take-off point limited to 120 metres, or the manufacturer must provide a means to limit the height
• The drone must be safely controllable by a pilot following the manufacturer's instructions
• If equipped with a follow-me mode, the distance between the drone and the pilot must not exceed 50 metres, and the function must be disengageable
• The drone must be placed on the market with a unique serial number that complies with the applicable standard
• For newer C0 drones, direct remote identification broadcast capability is required

The class marking is not a sticker that anyone can print and attach. It is a declaration by the manufacturer that the product has been designed, tested, and produced in compliance with the applicable technical standards. The manufacturer takes on legal responsibility for this declaration.

C0 vs Legacy Drones: The Practical Difference

Many sub-250g drones currently on the market were manufactured before the class marking system was fully implemented. These drones are classified as legacy drones. The distinction between a C0-marked drone and a legacy sub-250g drone matters because it affects which subcategory rules apply.

C0-Marked Drones

A drone with a C0 class marking can operate in subcategory A1 of the Open Category. This is the least restrictive subcategory, permitting:

• Flight over uninvolved persons, though not intentionally over assemblies of people
• No minimum horizontal distance from uninvolved persons
• Maximum height of 120 metres above ground level
• The pilot must hold a valid Operator ID and Flyer ID from the CAA

Legacy Sub-250g Drones

A legacy drone under 250g without a class marking can also operate in the Open Category, but the CAA's transitional provisions place it in a slightly different position. During the transition period, legacy sub-250g drones are generally permitted to fly under conditions similar to subcategory A1. However, as the transition period progresses and eventually concludes, the regulatory position for unmarked drones may become more restrictive.

The key difference in practice is future-proofing. A C0-marked drone has a defined and permanent place in the regulatory framework. A legacy drone's privileges depend on transitional arrangements that may change over time as the CAA refines its approach to the class marking system.

Remote Identification and C0 Drones

Remote identification is a system that allows a drone to broadcast its identification, position, and operator information during flight. For newer C0-marked drones, the manufacturer must include direct remote identification capability. This means the drone broadcasts its information directly via a radio signal that can be received by nearby devices, rather than transmitting through an internet-connected network.

The remote ID broadcast typically includes:

• The drone's unique serial number
• The operator's registration number
• The drone's current position (latitude, longitude, and altitude)
• The drone's ground speed and heading
• The position of the take-off point or the pilot
• A timestamp

Older C0-marked drones manufactured before the remote ID requirement was implemented may not have this capability. These drones retain their C0 status but may be subject to additional conditions as remote ID requirements are phased in across the UK drone ecosystem.

Remote ID serves several purposes: it helps authorities identify drones in flight, supports airspace management, and provides accountability. For the individual pilot, it means your flights are potentially identifiable to anyone with a remote ID receiver, including the CAA, police, and eventually members of the public using appropriate apps.

Can You Self-Apply a C0 Marking?

No. The C0 class marking is a manufacturer declaration. It indicates that the manufacturer has designed and produced the drone in compliance with the applicable technical standards and has taken responsibility for that compliance. A drone operator cannot retrospectively apply a class marking to a drone that was not manufactured with one.

This means that if you build a drone from components — as is common in the FPV community — your custom-built drone cannot receive a C0 marking regardless of its weight. Custom-built drones are treated as legacy drones under the regulatory framework. They can still fly in the Open Category under the transitional provisions, but they do not have the formal C0 designation.

Similarly, if a manufacturer produces a drone without applying for the class marking during the production process, the drone ships as a legacy product. The manufacturer cannot retroactively issue class markings to products already on the market without going through the appropriate conformity assessment process.

Buying a C0 Drone: What to Check

If the class marking is important to you when purchasing a drone, look for the following indicators:

1. The C0 marking should be physically displayed on the drone itself, typically on a label or engraving on the body
2. The product documentation should reference compliance with Commission Delegated Regulation (EU) 2019/945 or its UK retained equivalent
3. A Declaration of Conformity should be available from the manufacturer
4. The product listing should explicitly state the class marking, not merely the weight
5. Check whether the drone includes remote ID capability, as this indicates a newer C0-compliant model

Be cautious of listings that describe a drone as being in the C0 weight class without explicitly stating that it carries the C0 marking. Being under 250g and having a C0 marking are related but not identical. A drone can weigh under 250g without carrying the C0 marking if the manufacturer has not completed the conformity assessment.

The UK-EU Divergence Question

The C0 class marking system originated in EU regulation. Following Brexit, the UK retained this regulation as part of its domestic law. As of 2026, the UK continues to recognise the class marking system broadly consistent with the EU framework. However, the UK has the ability to diverge from the EU approach over time, and the CAA may introduce UK-specific requirements or modifications to the class marking system.

For drone operators, the practical implication is that a C0-marked drone purchased in the EU should be recognised in the UK, and vice versa, under the current framework. However, keeping informed about any future UK-specific changes to the class marking system is advisable, particularly if you fly in both jurisdictions.

The Bottom Line

The C0 class marking provides the clearest and most future-proof regulatory position for a sub-250g drone in the UK. It confirms that the drone meets specific technical standards, entitles the operator to fly in the least restrictive subcategory, and positions the drone within a defined regulatory framework that will continue to develop. If you are purchasing a new sub-250g drone, a C0-marked model offers the greatest regulatory clarity for the long term.