SAIL Marks and RAE(F)s Explained: The UK’s New ‘Pre-Approved Drone’ System for UK SORA

If you have started looking into the Specific Category and UK SORA, you have probably noticed something: the paperwork is not just about how you fly. It also gets very technical about the drone itself.

That's where SAIL Mark Certificates and RAE(F)s come in.

A simple way to think about it is:

• RAE(F) = an independent organisation the CAA recognises to check a drone’s safety and reliability.
• SAIL Mark = the official result of that check, showing what level of UK SORA operations the drone is suitable for.

The reason this matters is that it lets manufacturers prove the hard technical stuff once, so operators do not have to reinvent it every time they apply for an Operational Authorisation.

Quick glossary

Before we go deeper, here are the key terms in plain English.

UK SORA

UK SORA is the UK’s method for assessing risk in the Specific Category. It helps the CAA decide what safety measures you need for a particular operation.

SAIL

SAIL stands for Specific Assurance and Integrity Level. Ranging from SAIL I up to SAIL IV, it's basically a scale that helps describe how 'risky' the operation is from a safety assurance point of view.

A higher SAIL generally means:

• more potential risk to people on the ground and other airspace users
• stronger safety requirements
• more evidence needed to prove the aircraft and operation are robust

RAE(F)

An RAE(F) is a Recognised Assessment Entity for Flightworthiness. It is an independent organisation approved by the CAA to assess drones against UK SORA technical requirements.

The problem SAIL Marks solve

When people first hear “UK SORA”, they often assume it is mostly about operations:

• the ConOps
• your procedures
• pilot competence
• ground crew
• site management
• emergency plans

All of that matters, but UK SORA also requires evidence about the aircraft’s technical safety, for example:

• system reliability and failure modes
• command and control (C2 Link) reliability and backups
• what happens if the aircraft loses control
• whether any safety equipment actually works as claimed

For many operators, that's a problem, because most operators are not drone designers and cannot easily generate engineering-grade evidence.

Without a system like SAIL Marking, the same work gets repeated again and again:

• Operator A proves the aircraft is suitable
• Operator B proves the same aircraft is suitable
• Operator C repeats it again

That slows the industry down and pushes costs up.

What is a SAIL Mark?

A SAIL Mark Certificate is a UK CAA scheme that makes certain aircraft evidence reusable.

In simple terms, a SAIL Mark means:

This specific drone platform has been independently assessed against UK SORA requirements for a particular SAIL level, so operators can reference that evidence in their applications.

It is not:

• a UK or EU class mark (UK0 to UK6 / C0 to C6)
• an Operational Authorisation
• a pilot qualification
• something an operator can self-declare with a label

It is design-focused, not pilot-focused.

What does “SAIL II” or “SAIL III” mean to an operator?

You do not need to memorise the full SAIL scale to understand the practical point:

• SAIL II and SAIL III are “where the real commercial world starts” for lots of UK SORA operations.
• They are commonly associated with operations that are more complex than Open Category, including many BVLOS and infrastructure use cases.

If a drone is SAIL Marked at SAIL II or SAIL III, it is effectively being positioned as a practical platform for real UK SORA work.

What is an RAE(F) and what do they actually do?

An RAE(F) is a CAA-recognised assessor. Their job is to independently review technical evidence and confirm whether a drone meets certain UK SORA requirements.

Think of it like this:

• The operator is responsible for operating safely and proving the operation is safe.
• The manufacturer/designer is responsible for proving the aircraft is safe and reliable for its intended use.
• The RAE(F) is the independent body that can verify the aircraft side of that evidence.

RAE(F)s do not issue Operational Authorisations. They produce technical assessment outputs that can be used to support CAA decisions.

How SAIL Marks and RAE(F)s work together

The “reuse” model looks like this:

1. A manufacturer or designer prepares evidence about the aircraft.
2. An RAE(F) reviews and tests what is needed to assess that evidence.
3. If it meets the required standard, the aircraft can be awarded a SAIL Mark Certificate at a specific level.
4. Operators can then reference that SAIL Mark evidence in their UK SORA application.

For operators, the advantage is simple:

• less custom engineering work
• less duplicated evidence
• faster, more predictable applications
• fewer surprises late in the process

A useful tidbit: parachutes in UK SORA

Parachutes are a good example of why this system exists.

If you want to use a parachute as a UK SORA ground risk mitigation (often referred to as an M2 mitigation), it is not enough to say:

• “the parachute is rated for this weight”
• “the manufacturer says it reduces impact”
• “it worked on a different drone”

The CAA has explicitly confirmed that:

If you want to use a parachute as a UK SORA mitigation, the drone and the parachute system must be assessed together by an RAE(F).

This is because the parachute is part of a safety-critical system, and integration matters:

• deployment logic and triggers
• reliability and failure modes
• aircraft aerodynamics and drift under canopy
• whether the ground risk buffer still makes sense
• actual impact reduction in real conditions

This is exactly the kind of technical assurance that's difficult for operators to prove repeatedly, and far more efficient to assess at design level.

The government subsidy and what it means

The UK has recognised that a major blocker to UK SORA adoption is simply this:

There are not enough “ready to buy” aircraft that have already been assessed to SAIL levels commonly needed by commercial operators.

To fix that, the Department for Transport, the CAA, and UK Research and Innovation have launched a subsidy scheme to support SAIL Mark assessments for:

• four SAIL II UAS
• one SAIL III UAS
• to be delivered by 30 June 2026

In practice, this is the UK trying to seed the market with a small number of assessed, commercially available platforms, so UK SORA can scale without every operator and every manufacturer starting from scratch.

This funding is not about buying aircraft for operators. It is about helping cover the cost of independent assessment, which is often one of the biggest barriers for manufacturers.

What this means for operators

For beginner and intermediate operators moving towards UK SORA, the practical benefits are:

• more aircraft that are “UK SORA ready” off-the-shelf
• less bespoke evidence work for the aircraft side of the application
• lower cost and complexity when building the safety case
• more consistent expectations from the regulator

You still need a strong ConOps and operational evidence, but your aircraft choice becomes less of a gamble.

What this means for manufacturers

For manufacturers, the message is also clear:

• build and prove technical assurance once
• get a SAIL Mark
• make the platform easier to adopt in commercial UK SORA operations

A SAIL Mark becomes a form of “regulatory readiness”, not just a technical badge.

Final thoughts

If UK SORA is the UK’s system for approving higher-risk drone operations, SAIL Marks and RAE(F)s are the UK’s system for making the aircraft side of that approval scalable.

The goal is not to add bureaucracy. The goal is to remove duplication and make approvals more consistent:

• manufacturers prove the platform once
• independent assessors verify it
• operators reuse that evidence and focus on safe operations

that's why SAIL Marks are becoming a key part of the UK’s long-term plan for the Specific Category.