Do you build custom drones, develop your own autonomous technologies, or need to get a machine with non-standard sensors into operation? The operation of self-designed unmanned systems has its own specific place in EU legislation. While in the regular Open category you will encounter strict limits with them, the Specific category opens up space for legal and predictable operation – if you manage the risk assessment process correctly.

The operation of unmanned aerial systems (UAS) in the European Union is governed by a single regulatory framework based on: Commission Regulation (EU) 2019/947 a Commission Regulation (EU) 2019/945This framework introduced a three-tiered classification of operations according to the level of risk into categories open (Open), specific (Specific) a certified (Certified).

Although most drone operations are in the Open category with commercial aircraft classified as C0 to C4, there is a diverse group of operators who build their own drones. These are generally not eligible for the Open category and their operations fall into the more complex category. Specific.

Why do operators choose their own design?

The motivation to build your own drones affects the nature of the planned operations and thus the outcome of the risk assessment process. The most common areas are:

• Research and development: Academic institutions and startups are testing new software solutions, sensors, and algorithms for autonomous navigation and AI data analysis. The drone is a testing tool, not a final product.
• Specific industrial inspections: Energy or industrial companies need non-standard sensor combinations (thermal imaging, LiDAR, gas detectors) that are not offered on the market. Inspections of high-rise buildings and pipelines require specific load capacity and durability.
• Precision agriculture: Custom drone design for spraying, sowing or multispectral imaging tailored to specific crops.
• Rescue and security operations: Emergency services are experimenting with their own platforms for searching for people, monitoring fires, or transporting medical supplies in difficult weather conditions.
• Filmmaking and FPV flying: Professional cinematographic drones custom built for specific cameras or community FPV racing drones.

Open vs. Specific Categories: Where is the line?

Categories Open requires meeting precise parameters. A key prerequisite is the class designation C0–C4 (CE label), with which the manufacturer guarantees technical conformity. Drones of their own design do not inherently have this marking.

Exception in the Open category: Own drones can be operated in the subcategory A3, but under very restrictive conditions: line-of-sight operation (VLOS), weight up to 25 kg, maximum height 120 meters and minimum distance 150 meters from people and buildings.

Once you plan to fly above 120 meters, beyond visual line of sight (BVLOS), or near populated areas, you find yourself in the category Specific.

Key advantage of the Specific category

All unmanned systems can be operated in this category, including those without class C markingThis creates a legal space for drones of one's own design. The operator has three ways to obtain authorization:

1. Standard Scenarios (STS): Pre-approved frames, but require C5 or C6 class drones. For custom builds, they are therefore unusable.
2. Predefined Risk Assessment (PDRA): Simplified scenarios published by EASA (European Aviation Safety Agency). However, they are also subject to technical requirements that the actual building may not meet.
3. SORA methodology (Specific Operations Risk Assessment): Comprehensive, tailor-made risk assessment. It is a universal path that works for any drone regardless of its origin. For custom designs, it is main variant.

SORA methodology step by step

SORA is a Europe-wide recognized tool for classifying risks and defining safety objectives. The most important steps of the approval process include:

• ConOps (Concept of Operations): A detailed description of the planned operation (where, how high, over what terrain and with what safety features the flight will be conducted).
• Ground Risk Class (GRC): Ground risk assessment (threat to people and property on the ground), which depends on the weight, speed of the drone and population density.
• Air Risk Class (ARC): Air risk assessment (probability of collision with a manned aircraft) based on the nature of the airspace.
• Determining the SAIL level: The resulting value for grades I to VI. The ratio applies: the higher the SAIL, the stricter the requirements for technology, training and documentation.
• Operational safety objectives (OSO): Specific technical and operational requirements (reliability, emergency procedures, flight termination systems), the robustness of which depends on the SAIL level.

SAIL level and the bogeyman called Design Verification Report (DVR)

The SAIL level determines whether a simple operator declaration is sufficient to demonstrate technical competence, or whether it will be necessary to have a Design Verification Report (DVR) from EASA. For custom designs, the technical requirements must be demonstrated by the operator, not the manufacturer.

SAIL level	Risk level	Technical verification requirement
SAIL I and II	Low risk	As a rule, the operator's own declaration is sufficient (however, the Customs Office may request a DVR).
SAIL III	Medium risk	Approaches vary. EASA allows declarations, but the Czech Civil Aviation Authority (ÚCL) requires DVR as standard.
SAIL IV	Medium risk	The development of a DVR is required as standard.
SAIL V and VI	High risk	A regime similar to the certification of manned aircraft. A Type Certificate issued by EASA is required.

Practical recommendation: The first step for any designer should be to pre-determine the SAIL level, which determines the complexity of the entire process and the involvement of international authorities.

Administrative proceedings before the Civil Aviation Authority (CAA)

Once you have completed the SORA analysis, you apply for Authorization to operate (OkP) at the Customs Office. A complete file typically contains:

1. Operating permit application form
2. SAIL designation form
3. Operational Safety Objectives (OSO) Form
4. ConOps document (for SAIL II and higher expanded to form Operating manuals)
5. Declaration on personal data protection

The design of the drone itself is not an obstacle to the approval of even very demanding aerial operations. The SORA methodology was designed precisely for these situations. The key to successful and rapid approval is optimization of ConOps parameters right from the startBy choosing the right location, flight altitude and integrating reliable technical elements (e.g. a parachute system), the resulting risk – and therefore the administrative complexity – can be significantly reduced.

Source: epravo.cz

Do you have a drone of your own design and want to operate it in accordance with the law? Contact us! We will help you with everything.

JUDr. Ing. Jan Vych, attorney and partner

Mgr. Kristina Martinkova, paralegal