Identifying acceptable standards under UK SORA from SAIL 3 onwards: BSI Flex 1906 as your Guide

With the UK SORA (Specific Operations Risk Assessment) officially in force since 23 April 2025, operators now have a new, structured Acceptable Means of Compliance (AMC) to Article 11 of UK Regulation (EU) 2019/947, which governs “Rules for conducting an operational risk assessment.”

One of the questions that arises from UK SORA is:

👉 When the UK SORA methodology calls for the use of a standard or other Means of Compliance (MoC) acceptable to the CAA—which standards or MoCs is the methodology referring to?

The answer isn’t straightforward. The body of standards specifically tailored for uncrewed systems is still emerging. While there’s a wealth of existing standards developed for crewed aviation, identifying which ones are suitable and proportionate for uncrewed operations is a real challenge.

Enter BSI Flex 1906

BSI Flex 1906 was developed to help navigate this exact complexity.

Its purpose is to map existing standards and MoCs to the UK SORA requirements, up to SAIL3.

The work builds on technical assessments already performed under Project SHEPHERD (2021–2024) in Europe, and also considers MoCs developed by EASA where relevant to the UK context.

Scope of BSI Flex 1906

BSI Flex 1906 focuses on those UK SORA elements where a standard or MoC is explicitly referenced as a requirement. It examines whether appropriate, existing standards or MoCs are available and applicable.

Here’s a snapshot of key findings:

UK SORA item	CAA ref code	Level of SAIL/robustness	Are there applicable existing standards or MoC?
OSO 2  UAS Manufactured by competent entity	OSO2 LA	Sail 3 and above	❌No
OSO 3 UAS maintained by competent entity	OSO3 C1 MA	Sail 3 and above	⚠️Partially
OSO 8 Operational procedures are defined	OSO8 MA	Sail 3 and above	✅ Yes/Partially
OSO 16 Multi Crew Coordination	OSO16C1 MA	Sail 3 and above	❌No
Containment	COT C4 MI	Medium or high robustness	✅ Yes
Containment(tether)	COT C2 MA	Medium or high robustness	❌No
M2 Effects of UA impact dynamics	M2C2 MA	Medium or high robustness	⚠️Partially
M2 Effects of UA impact dynamics	M2C1 HA	High robustness	⚠️Partially
FTB Functional Test-bed		General	❌No

Where an existing standard is cited but wasn’t originally developed for uncrewed aviation, it encourages critical thinking: Is it proportionate? Is it applicable?

Remember: the development of standards for uncrewed systems is still in its early stages. BSI Flex 1906 is one of the first tools designed to bridge the gap.

The BSI Flex 1906 technical author was Anthony Venetz acting on behalf the British Standards Institute. The work was supported and funded by UK Research and Innovation UKRI through UKRI Future of Flight Challenge.

Anne-Lise Scaillierez was a member of BSI Flex 1906 Advisory Board, representing ARPAS-UK.