The UK Civil Aviation Authority’s introduction of the Recognised Assessment Entity for Flightworthiness, or RAE(F), and the associated SAIL Marking system was presented as a way to support the rollout of UK SORA and help operators demonstrate that their unmanned aircraft systems are safe for more complex Specific Category operations.
In principle, few people in the drone industry would object to proportionate safety assurance. The problem is not the intent. The problem is the way the system risks becoming another costly layer of
assessment on top of standards, certificates, declarations and component-level compliance work that manufacturers have already completed.
The CAA says RAE(F)s are approved to assess whether the technical features of a UAS meet UK SORA requirements, including design, construction and flying characteristics. It also states that designers seeking a SAIL Mark must ask an RAE(F) to assess the UAS, after which the RAE(F) advises the CAA whether the requirements have been met. (Civil Aviation Authority)
That sounds reasonable until you look at what many drone manufacturers are actually building. A modern drone is typically assembled from radios, flight controllers, GPS receivers, batteries, transmitters, electronic speed controllers and other components that already sit within an established conformity framework. Radio equipment is already subject to applicable radio and EMC requirements. CE-marked products and components are already required to demonstrate compliance with applicable Union harmonisation legislation.
EASA’s own guidance for manufacturers confirms that drones are subject to legislation such as the
Radio Equipment Directive and Machinery Directive, and that manufacturers must demonstrate compliance through the defined conformity procedures before affixing CE marking. (EASA)
So the question the industry should be asking is simple: what additional safety value is actually being created by the RAE(F) process, and what is merely a re-check of paperwork that already exists?
The SAIL Mark system is described by the CAA as optional; CAP 722K explicitly states that there is “no obligation” for a UAS designer to SAIL mark their aircraft in the UK. However, the practical reality may become very different. If operators increasingly need SAIL marked aircraft to make UK SORA applications easier, then an “optional” scheme can quickly become a commercial necessity. Once that happens, manufacturers who cannot afford the cost, delay and administrative workload of SAIL Marking may find themselves excluded from parts of the market, even when their aircraft are built from compliant, traceable and already-certified components.
This is where the system becomes problematic. The RAE(F) does not replace proper engineering by the manufacturer. It does not design the aircraft. It does not manufacture the aircraft. In many cases, it will not add meaningful physical test data beyond what the manufacturer has already generated.
CAP 722K requires the designer to submit evidence data to the RAE(F), and the RAE(F) must verify the designer’s compliance against the agreed compliance basis and approach. That is fundamentally an evidence-review model.
Evidence review has value where the aircraft is novel, high-risk, complex, or where the manufacturer is claiming safety functions that are not already proven. But it is much harder to justify when the review becomes a costly confirmation that standard components meet standards they have already been tested against. For example, CAP 722K’s C3 link requirements require data such as C3 link performance, RF spectrum and environmental conditions, plus evidence that the remote pilot can monitor C3 link performance.
Those are important issues, but for many systems the underlying radio modules, output powers,
frequency bands and conformity evidence already exist. The danger is that the RAE(F) becomes an expensive intermediary between the manufacturer’s existing technical file and the CAA’s approval process.
The CAA’s own charging structure shows the wider cost environment that manufacturers and operators now face. For 2026/27, UK SORA-based Operational Authorisation charges range from £2,422 at SAIL 1 to £17,300 at SAIL 5 and SAIL 6, with additional assessment charges possible at £346 per hour. These are CAA charges, not necessarily the full commercial cost of engaging an RAE(F), but they demonstrate the direction of travel: higher SAIL means higher cost, more documentation, more assessment and more delay. (Civil Aviation Authority) EASA’s Design Verification Report system raises similar concerns. EASA states that DVR costs are based on actual time spent assessing documentation, charged at €250 per hour, and that the duration depends heavily on system complexity and the manufacturer’s responsiveness. Again, this is a documentation-heavy model that may be appropriate for higher-risk or more novel designs, but it risks becoming disproportionate when applied too broadly. (EASA)
The strongest argument for SAIL Marking is that it allows a manufacturer to prove the technical aspects once, so operators do not have to repeat the same evidence for every Operational Authorisation. That is a valid objective. The CAA itself says that as more SAIL-marked UAS become available, operators will be able to use them to comply with certain UK SORA technical requirements. (Civil Aviation Authority)
But that benefit only materialises if the process is quick, affordable, consistent and genuinely additive. If the system is slow, expensive and mostly duplicates existing component compliance, then it will not accelerate innovation. It will tax it.
This concern is not just theoretical. In consultation feedback submitted to the CAA, the Royal Aeronautical Society warned that limited numbers of organisations providing RAE(F) services could increase industry costs, extend authorisation timelines and limit growth. The same response noted that many UK drone manufacturers are SMEs, often developing products with limited revenue, and that overly burdensome regulation can make compliance expensive and time-consuming during the critical period before a product is commercialised.
That is the core issue. The UK drone industry is not made up only of large aerospace primes with dedicated certification departments. Much of the innovation comes from small manufacturers, engineering-led start-ups and specialist operators building practical systems for real-world use cases. These companies already face costs for product development, testing, insurance, manufacturing, software, documentation, operational approvals, training, export compliance and market access. Adding another expensive assessment layer may satisfy an administrative need, but it can easily become a barrier to entry.
There is also a risk of regulatory mismatch. Drone technology evolves quickly. Components change, firmware changes, radio modules change and payloads change. A certification-style model that works for traditional aviation can become misaligned with the pace of unmanned aircraft development. The more the approval system struggles to keep up with real product cycles, the more manufacturers will either delay innovation, avoid the UK market, or design around the approval process rather than around the best technical solution.
The answer is not to abandon safety assurance. The answer is proportionality.
For low and medium-risk SAIL levels, the CAA should allow more reliance on manufacturer declarations, existing CE/UKCA/RED evidence, component certificates, conformity documentation and controlled internal test reports. RAE(F) involvement should focus on genuinely operation-specific or system-level risks: containment, failure modes, command-and-control resilience, geofencing, flight termination, software behaviour and manufacturing consistency. It should not become a paid exercise in re-reading radio module certificates and checking that standard parts already comply with standards they were built to meet.
A better model would separate “paperwork already proven elsewhere” from “system-level flightworthiness claims.” If a manufacturer uses a compliant radio module within its rated power, frequency and environmental envelope, that should not need a full reassessment. If a manufacturer claims that its drone can safely terminate flight, contain itself within a defined volume, detect C3 degradation or maintain operational control in a swarm, then that is where independent assessment can add value.
The UK has an opportunity to build a sensible, risk-based drone approval system. But if RAE(F) and SAIL Marking become too expensive, too slow, or too focused on duplicating existing standards, the result will not be a thriving ecosystem. It will be a smaller market, fewer manufacturers, slower product development and less innovation.
The CAA may see the creation of the RAE(F) system as a step forward. For parts of the industry, it may well be. But unless the system is kept proportionate, transparent and affordable, it risks becoming exactly what manufacturers fear: an expensive double-check on compliant products, paid for by the very companies the UK needs if it wants to lead in unmanned aviation.
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