UK5 and UK6 – Why Class Marks Work Differently in the UK

UK drone regulation includes class marks from UK0 to UK6, but not all of them currently have a practical effect on how you are allowed to fly. UK5 and UK6 are the most commonly misunderstood. They exist in UK law, but they do not currently unlock any operational privileges, and they do not change how UK SORA (UK Specific Operations Risk Assessment), the UK’s risk-based approval process for Specific Category operations, is applied.

This article explains where UK5 and UK6 sit right now, how the 2026 class-mark transition affects most pilots, how class marks work in general, and why UK5 and UK6 remain largely dormant in the UK compared to EU C5 and C6.

TLDR: From 2026, UK class marks become the standard way new drones are categorised, but UK5 and UK6 still do not provide any operational shortcuts in the UK. There is no UK Standard Scenario (STS, a pre-defined operational approval route), and UK SORA does not use class marks. For now, UK5 and UK6 exist for future alignment rather than present-day permissions.

See also: UK Drone Regulations 2026 · Understanding UK SORA · PDRA-01 Explained

Where Things Stand Right Now

UK drone regulation currently operates across two related but separate layers of law.

• Product regulation (UK Regulation (EU) 2019/945) covers how drones are designed and placed on the market, including UK class marks.

• Operational regulation (UK Regulation (EU) 2019/947) defines where and how drones may be flown, including the Open Category and Specific Category. Risk-based authorisation covers approvals such as UK SORA and PDRAs (Pre-Defined Risk Assessments).

These layers interact, but they are not interchangeable.

Right now, no UK operational route requires a UK5 or UK6 aircraft. There is no UK Standard Scenario (STS), no new PDRA, and no UK SORA pathway that references those class marks.

What Changes in 2026, Briefly

From 1st January 2026, any new model placed on the UK market must have a UK class mark where applicable. Legacy models can continue to be sold without a UK class mark until 1st January 2028.

For most pilots, the practical impact of 2026 is felt in the Open Category, where UK0 to UK4 class marks clearly define which sub-category an aircraft can be flown in and under what conditions.

What does not change in 2026 is the absence of a UK Standard Scenario (STS) framework. Because of this, UK5 and UK6 still do not trigger any automatic permissions or simplified approval routes.

Want to learn more about the 2026 changes? Read the explainer: UK Drone Regulations 2026

A Short Explanation of UK Class Marks

UK class marks are manufacturer declarations confirming that an aircraft meets a defined set of technical and safety requirements set out in product regulation.

• UK0 to UK4 are directly tied to Open Category flying. They determine proximity to people, separation distances, and which sub-category applies.
• UK5 and UK6 sit above the Open Category and are intended to describe aircraft designed for Specific Category operations.

A class mark describes how an aircraft is built, not whether a particular operation is approved. A class mark on its own never authorises flight.

What UK5 and UK6 Are Intended to Represent

UK5 and UK6 are the UK equivalents of the EU’s C5 and C6 class marks. Conceptually, they are intended to identify aircraft designed for more complex and higher-risk operations, often associated with longer ranges, stronger command and control links, and higher system integrity.

They indicate that an aircraft was designed with Specific Category operations in mind, rather than recreational or low-risk commercial flying.

In the UK, however, that design intent currently has no operational hook.

Why UK5 and UK6 Do Not Unlock Anything Yet

The reason UK5 and UK6 feel unusable is regulatory, not technical.

In the EU, C5 and C6 are explicitly linked to Standard Scenarios (STS). If an operator uses the correct class of aircraft (one that has already demonstrated compliance through its class mark) and follows the regulator’s pre-defined operating conditions, they may operate without completing a full SORA.

The UK has not adopted Standard Scenarios and has not introduced UK equivalents. There is also no UK PDRA that requires or references UK5 or UK6.

UKPDRA-01 (UK Pre-Defined Risk Assessment 01), which remains the only published PDRA in the UK, allows aircraft up to 25 kg and makes no distinction based on class marks. UK SORA similarly does not ask for class marks at any stage of the assessment.

As a result, UK5 and UK6 exist in product regulation but are not used operationally.

How UK SORA Actually Treats Aircraft

Under the UK Specific Operations Risk Assessment (UK SORA), the CAA (Civil Aviation Authority) looks at the risk of the whole operation, not whether a drone carries a label like UK5 or UK6. UK SORA is the process used to show that a Specific Category operation can meet the required level of safety, based on evidence rather than product markings.

UK SORA breaks risk into two parts:

• Ground risk – the chance of causing harm to people or property on the ground
• Air risk – the chance of a collision with other aircraft

Both are assessed using structured models that take account of how and where the drone will be flown.

Aircraft characteristics feed directly into these assessments. Things like size, weight, speed, impact energy, how the aircraft behaves if something fails, the reliability of command and control, and the operating environment all influence the outcome.

These factors are used to determine the Ground Risk Class (GRC) and Air Risk Class (ARC), which are then combined to give a Specific Assurance and Integrity Level (SAIL) for the operation. A higher SAIL simply means more safety evidence and stronger mitigations are required.

A UK5 or UK6 class mark does not change any of this. Two aircraft with the same performance, failure behaviour, and operating profile will receive the same GRC, ARC, and SAIL under UK SORA, whether they are class-marked or not.

This is why UK SORA approvals often include legacy drones, bespoke systems, and experimental aircraft, as long as the risks are properly assessed and controlled.

RAE(F), Flightworthiness, and SAIL Marks

For some UK SORA applications, the CAA allows the use of a Recognised Assessment Entity for Flightworthiness, known as an RAE(F).

An RAE(F) is an organisation approved by the CAA to carry out independent technical assessments of a drone’s design and flightworthiness. This can be useful where an operation relies on technical mitigations that need specialist evidence.

An operator or manufacturer may use a RAE(F) to produce a flightworthiness report, which can be submitted alongside a SORA application to support the proposed SAIL.

RAE(F)s also support SAIL Mark Certificate applications. The RAE(F) assesses the UAS against the requirements and advises the CAA, and if the CAA agrees the requirements are met, it will grant a SAIL Mark Certificate. This is not permission to fly, but it can reduce the amount of repeated technical evidence needed for future SORA applications.

Unlike UK5 or UK6 class marks, which are manufacturer declarations, SAIL Marks are based on independent assessment and are directly relevant to how UK SORA evaluates safety evidence.

EU C5 and C6 Versus the UK Position

In the EU, C5 and C6 matter because they are directly wired into operational pathways through Standard Scenarios.

In the UK, that operational layer does not exist. The product framework was retained, but the scenario-based operational framework was not.

As a result, UK5 and UK6 currently act as placeholders, allowing future UK Standard Scenarios or class-linked PDRAs to be introduced without rewriting product law.

What Might Change in Future

If the UK introduces UK Standard Scenarios (STS) or additional PDRAs beyond UKPDRA-01, UK5 and UK6 are the obvious class marks those documents would reference.

Until that happens, they remain defined in law but unused in practice.

Frequently Asked Questions

Do I need a UK5 or UK6 drone to fly under UK SORA?
No. UK SORA does not require or reference class marks. Approval is based on risk evidence.

Does UKPDRA-01 require a specific class mark?
No. UKPDRA-01 allows aircraft up to 25 kg regardless of class marking.

Are UK5 and UK6 the same as EU C5 and C6?
They are conceptually equivalent, but the UK does not currently have the operational framework that makes them useful in the same way.

Will UK5 and UK6 matter in future?
Possibly. If the UK introduces Standard Scenarios or class-linked PDRAs, they are likely to be referenced then.