Drone Class C4 UK Rules

What Is a Class C4 Drone?

Class C4 is the EASA category specifically created for traditional model aircraft. It covers drones and model aircraft with a maximum take-off mass (MTOM) below 25 kilograms — the same weight ceiling as Class C3 — but with one critical distinction: C4 drones must not be equipped with any automatic control modes.

This means no autopilot stabilisation, no GPS-assisted hovering, no automated return-to-home, no waypoint navigation, and no follow-me or orbit modes. The pilot must maintain full manual control of the aircraft at all times using a transmitter. This class exists to provide a regulatory pathway for the longstanding model aircraft community, whose members have been building and flying radio-controlled aircraft for decades.

Why Does C4 Exist?

When EASA introduced the harmonised drone regulations, traditional model aircraft enthusiasts faced a challenge. Their large fixed-wing models and helicopters — often hand-built and weighing 10kg or more — did not fit neatly into the consumer drone categories designed around DJI-style quadcopters.

C4 bridges this gap. It allows model aircraft to operate within the Open category framework without requiring the automatic flight features that define modern multi-rotor drones. The no-autopilot rule is not a limitation for model aircraft pilots — it simply reflects how they already fly. Manual skill, not software, keeps the aircraft in the air.

Unlike C3, there is no maximum characteristic dimension limit for C4 drones, as long as the total weight stays under 25kg. This accommodates large-wingspan fixed-wing models that would exceed the C3 four-metre limit.

Where Can You Fly a C4 Drone?

C4 drones operate in the Open A3 subcategory, with the same location restrictions as C3:

• 150-metre buffer: Maintain at least 150 metres of horizontal distance from any residential, commercial, industrial, or recreational area.
• No uninvolved people: Your flying area must be clear of uninvolved persons. If people enter the area, take immediate action to maintain safe separation.
• Maximum altitude: 120 metres (400 feet) above ground level.
• Visual line of sight: Maintain direct, unaided visual contact with the aircraft throughout the flight.
• Flight Restriction Zones: Stay out of FRZs around protected aerodromes unless you have CAA authorisation.

In practice, C4 operations typically take place at dedicated model flying clubs, open farmland with landowner permission, or designated model aircraft fields managed by organisations such as the British Model Flying Association (BMFA).

Training and Registration

• Operator registration: Mandatory via the CAA drone registration service. Annual fee of £10.33.
• Flyer ID: Complete the CAA's free online theory test to obtain your Flyer ID.
• Operator ID display: Must be visible on the aircraft.

No A2 CofC is required. The training requirements for C4 are the same baseline as any Open category drone. However, model flying clubs often provide their own training programmes, proficiency tests, and insurance schemes that go well beyond the CAA minimums.

Model Flying Clubs and Article 16 Authorisations

Many model aircraft enthusiasts in the UK fly at clubs that hold an Article 16 authorisation from the CAA. These authorisations, typically obtained through the BMFA or the Large Model Association (LMA), allow clubs to operate under alternative rules — for example, flying above the 120-metre altitude limit at approved sites, or within areas that would otherwise require greater separation distances.

If you fly a C4-class model aircraft, joining a recognised club can expand your operational permissions significantly. Club membership also typically includes third-party liability insurance, access to maintained flying sites, and mentoring from experienced pilots.

C4 vs C3 — The Key Distinction

• Automation: C3 allows full autopilot and automated flight modes. C4 prohibits them entirely. This is the defining difference.
• Dimension limit: C3 drones must not exceed 4 metres in their largest dimension. C4 has no dimension limit within the 25kg MTOM ceiling.
• Target user: C3 is for professional operators using automated survey and inspection platforms. C4 is for manual-control enthusiasts flying traditional model aircraft.
• Subcategory: Both operate in A3. The flying location rules are identical.

Is Class C4 Right for You?

C4 is the natural home for anyone who builds, flies, and maintains traditional radio-controlled model aircraft. If you prefer manual stick-and-rudder control over software-assisted flight, if your aircraft has no GPS module or flight controller with automated modes, and if you typically fly at a club or in open countryside, C4 is your regulatory pathway.

If you need automated features — even basic GPS hover or return-to-home — you will need a C3 or lower class mark instead. The no-autopilot rule is absolute: a drone with any automatic flight capability, even if it is switched off during flight, does not qualify for C4 classification.