Drone Specific Category Operations in the UK

When Open Category Is Not Enough

The Open Category works for many everyday drone operations, but it has hard limits. You cannot fly over assemblies of people, operate beyond visual line of sight, enter controlled airspace, or use drones heavier than 25 kilograms. When any of these limits is exceeded, the operation moves into the Specific Category, and you need prior authorisation from the Civil Aviation Authority.

The Specific Category exists to handle the middle ground between the relatively unregulated Open Category and the fully regulated Certified Category. It covers operations where the risk to people on the ground or to other airspace users is elevated, but not to the level where full aircraft-type oversight is warranted. The vast majority of professional drone operations that go beyond recreational or basic commercial work fall into this category.

Typical operations requiring Specific Category authorisation include infrastructure inspections conducted beyond visual line of sight, aerial surveys over populated areas, flights within controlled airspace near airports or military installations, operations with drones exceeding Open Category weight limits, and flights over gatherings of people such as sporting events or public ceremonies.

The Two Routes to Authorisation

Route 1: Pre-Defined Risk Assessment (PDRA)

PDRAs are standardised operational scenarios that the CAA has already assessed and approved. If your intended operation matches a published PDRA exactly, you can apply for an OA based on that PDRA without conducting a full bespoke risk assessment. This significantly simplifies and accelerates the application process.

Each PDRA specifies the permitted operational conditions in detail: the type of airspace, maximum drone weight, altitude limits, distance from people, crew requirements, and any mandatory technical features such as detect-and-avoid systems. The CAA publishes the available PDRAs and may add new ones as technology and operational experience develop.

To use a PDRA, you must demonstrate that your operation fits within every parameter of the selected scenario. If any aspect of your operation deviates from the PDRA, even slightly, you cannot use that route and must pursue a bespoke OA instead. The benefit of the PDRA route is speed and predictability, but its limitation is rigidity.

Route 2: Bespoke Operational Authorisation (SORA)

For operations that do not match any published PDRA, you must apply for a bespoke OA. This requires conducting a Specific Operations Risk Assessment using the SORA methodology. SORA is a structured, quantitative framework developed by JARUS and adopted by the CAA for evaluating the risk of drone operations.

The SORA process involves several steps. First, you define your Concept of Operations (ConOps), which describes in precise detail what you intend to do, where, how, and with what equipment. Then you assess both the ground risk, meaning the risk to people and property on the surface, and the air risk, meaning the risk of collision with other aircraft. Based on these assessments, SORA assigns a Specific Assurance and Integrity Level (SAIL) from I to VI, with higher levels requiring more stringent mitigations.

The mitigations you must demonstrate correspond to the SAIL level. At lower SAIL levels, standard operating procedures and pilot competency may suffice. At higher SAIL levels, you may need specialised equipment such as parachute recovery systems, detect-and-avoid technology, or redundant command-and-control links. Each mitigation must be documented and, in many cases, independently verified.

The Concept of Operations (ConOps)

The ConOps document is the foundation of any Specific Category application. It is not a form to fill in but a comprehensive description of your operation that demonstrates you have thought through every aspect of what you plan to do. The CAA reviews your ConOps as part of the OA assessment, and its quality directly affects whether your application succeeds and how quickly it is processed.

A thorough ConOps typically includes:

• A description of the operation: what you are doing, why, and where
• The drone platform: type, class marking if applicable, maximum take-off mass, performance characteristics, and any modifications
• The operating environment: airspace classification, terrain, weather limitations, and ground characteristics
• Crew composition: remote pilot qualifications, observer roles, and any specialist personnel
• Normal operating procedures: pre-flight checks, take-off, flight execution, landing, and post-flight procedures
• Abnormal and emergency procedures: what happens if communication is lost, the drone malfunctions, weather deteriorates, or an intruder enters the operating area
• Risk mitigations: how you reduce the ground risk and air risk to acceptable levels
• Insurance: evidence of adequate third-party liability coverage

BVLOS Operations

Beyond Visual Line of Sight operations are among the most common reasons for entering the Specific Category. In the Open Category, the remote pilot must maintain direct, unaided visual contact with the drone at all times (corrected vision such as glasses or contact lenses is permitted, but binoculars, monitors, and FPV goggles do not count as visual line of sight).

BVLOS operations remove this restriction, allowing drones to fly beyond what the pilot can directly see. This capability is essential for long-distance infrastructure inspections, such as pipeline monitoring, railway surveys, power line checks, and agricultural mapping of large estates. It is also the foundation for future drone delivery services and urban air mobility concepts.

The CAA applies particular scrutiny to BVLOS applications because the pilot's inability to visually detect and avoid other aircraft and obstacles increases the air risk significantly. BVLOS authorisations typically require electronic conspicuity measures, detect-and-avoid systems, redundant command-and-control links, and detailed emergency procedures including automated return-to-home and flight termination capabilities.

Timeframes and Costs

Processing times for Specific Category applications vary depending on complexity. PDRA-based applications, where the operation fits a standardised scenario, are generally processed faster because the risk assessment framework is already established. The CAA aims to process straightforward PDRA applications within weeks.

Bespoke OA applications using SORA take longer. A well-prepared application with a thorough ConOps and clear risk mitigations might take several weeks to a few months. Complex BVLOS operations or applications in sensitive airspace can take considerably longer, especially if the CAA requests additional information or modifications to the proposed mitigations.

The CAA charges fees for processing OA applications, and these fees are published on the CAA website. They vary by the complexity of the assessment required. Budget for both the application fee and the time investment in preparing the ConOps and supporting documentation. Many operators find that investing in professional consultancy support for their first application saves time and increases the likelihood of approval.

Operating Under Your OA

Once granted, an Operational Authorisation specifies exactly what you are permitted to do. It will state the geographic area, altitude limits, time restrictions, drone types, crew requirements, and any conditions or limitations. You must operate strictly within the terms of your OA. Any deviation requires either an amendment to your existing OA or a new application.

OAs have an expiry date and must be renewed before they lapse. The CAA may also attach conditions requiring you to report incidents, maintain records, or submit to audit. Failure to comply with the terms of your OA can result in its suspension or revocation, and may lead to enforcement action under the Air Navigation Order.

You must carry a copy of your OA, or have it readily accessible, whenever you conduct operations under it. If challenged by the CAA, police, or other authorities, you must be able to demonstrate that your operation is authorised and that you are operating within the permitted parameters.

From Specific to Certified

If your operation involves carrying people, transporting dangerous goods, or operating over dense urban areas in a manner comparable to manned aviation, you may find that even the Specific Category is insufficient. These highest-risk operations fall into the Certified Category, which requires full aircraft-type oversight, licensed pilots, and an approved operator organisation. The boundary between Specific and Certified is defined by the level of risk and the regulatory oversight needed to manage it.