Multi-aircraft operations under EASA's Specific category

Organisations planning to run several drones in Europe quickly run into the question of which regulatory category their operation falls into, and what they need before they can fly. This note gives an overview of the EU framework as it applies to multi-aircraft operations. It is a summary to help with planning, not legal advice: requirements are applied by national aviation authorities and details change, so always confirm with the authority responsible for where you fly.

The three categories

EU rules for drone operations, set out in Commission Implementing Regulation (EU) 2019/947 and applied across EASA member states, sort operations into three categories by risk rather than by the type of aircraft:

Open covers lower-risk operations within defined limits: aircraft under 25 kg, flown within visual line of sight, generally no higher than 120 m above the ground, and away from people according to the subcategory. No prior authorisation is needed, though operators register and remote pilots need the appropriate competency.
Specific covers operations that fall outside the Open limits but do not reach the risk level of manned aviation. These need either an operational authorisation from the national authority, a declaration under a standard scenario, or a light UAS operator certificate.
Certified covers the highest-risk operations, such as carrying people or transporting dangerous goods in some circumstances, and is regulated much like manned aviation.

Why multi-aircraft operations usually end up in Specific

The Open category is built around one remote pilot flying one aircraft they can see. Operating more than one aircraft at the same time, or having one pilot supervise several aircraft, is outside what the Open category allows. Operations that scale often also involve flying beyond visual line of sight, over or near populated areas, or with heavier aircraft, each of which on its own points towards the Specific category.

Note the distinction between having a fleet and flying several aircraft at once. An organisation with ten aircraft, each flown separately by its own pilot within Open limits, may stay in the Open category. It is the nature of each operation, not the size of the fleet, that determines the category.

Routes to operating in the Specific category

There are several ways to obtain permission, depending on how standard the operation is:

Standard scenarios (STS). For operations that match a published scenario, the operator submits a declaration to the authority rather than applying for an authorisation. The scenarios are narrow, and operations involving several aircraft at once are unlikely to fit them as written.
Pre-defined risk assessments (PDRA). EASA publishes risk assessments for common operation types. Operators whose operation matches a PDRA can apply for an authorisation using it, which simplifies the application considerably.
A full risk assessment. For anything else, the operator carries out a risk assessment, usually following the SORA (Specific Operations Risk Assessment) method, and applies for an operational authorisation on that basis. This is the most common route for novel or complex multi-aircraft operations.
Light UAS operator certificate (LUC). Established operators can apply for an LUC, which allows them, within its terms, to authorise their own operations without applying to the authority each time. It is a significant organisational undertaking and suits operators with a mature safety management system.

What a risk assessment looks at

SORA evaluates two kinds of risk: ground risk, the chance of harming people on the ground, and air risk, the chance of conflict with other aircraft. Both are estimated from the operation's characteristics, then reduced through mitigations such as operating over sparsely populated areas, using parachutes, or flying in segregated airspace. The outcome is a level of robustness the operator must demonstrate across a set of operational safety objectives covering technical design, procedures, training and organisation.

For multi-aircraft operations, the assessment will look closely at questions such as:

How many aircraft one remote pilot can safely supervise, and how workload is managed when several need attention at once.
How the system behaves when one or more aircraft lose their link, and whether failures in one aircraft can affect the others.
How aircraft are kept separated from each other and from other airspace users.
How the human-machine interface presents the state of several aircraft clearly.
How operations are planned, monitored and recorded.

Where software fits in

Many of the mitigations and objectives in a Specific category application depend directly on software: fleet monitoring and alerting, contingency behaviour on link loss, geofencing, flight planning that respects authorised areas, and records that show the operation ran as described. Authorities will want to see evidence that this software behaves as claimed, which is one reason disciplined testing and logging matter. We discuss those practices in What reliable drone software looks like in practice.

Practical advice

Talk to your national authority early. Most are willing to discuss a planned operation before a formal application.
Start with the simplest operation that delivers value, get it authorised and build a track record before expanding.
Design your operations manual, procedures and software together, so the application describes what the system really does.
Keep the records you will need to show the authority from the first flight onward.

Moving into the Specific category is a real step up in effort, but it is also what makes larger and more ambitious operations possible. Treated as a design exercise rather than a paperwork exercise, it tends to produce safer and more efficient operations as well.