Drone Glossary

Abbreviation for Advanced Air Mobility – a collective term for new, mostly highly digitized air transport concepts (manned and unmanned aircraft), e.g., eVTOL air taxis and automated cargo drones, including the necessary infrastructure and operating procedures.

Surveillance technology in which aircraft automatically transmit their identity, position, and other data (e.g., via GNSS). ADS-B is used for airspace surveillance and situational awareness (ADS-B Out/In), among other things.

ADS-L (Automatic Dependent Surveillance – Light) refers to a family of light broadcast protocols for electronic conspicuity, in which GNSS-based position/identity data is transmitted over a short range. ADS-L is not identical to ADS-B and is not directly compatible with ADS-B (1090 MHz).

Advanced Air Mobility (AAM) describes the integration of novel aircraft and operating models (e.g., eVTOL, autonomous/remote-controlled systems, drone logistics) into regular air traffic—with a focus on scalability, safety, automation, and (often) low-emission propulsion systems.

Altitude measurement relative to the local terrain surface. AGL is practical for UAS because many operating limits (e.g., 120 m) refer to altitude above ground level.

Government publication containing aeronautical information of permanent importance for air navigation (e.g., structures, procedures, aerodromes).

Airspace Class A: Only IFR flights are permitted; all flights receive ATC service, are separated from each other, and require ATC clearance; continuous radio communication is required.

Airspace Class B: IFR and VFR are permitted; all flights receive ATC service, are separated from each other, and require clearance; continuous radio communication is required.

Airspace Class C: IFR and VFR are permitted; ATC service for all. IFR is separated from IFR and VFR; VFR is separated from IFR and receives traffic information (and, upon request, avoidance advice); clearance and radio communication are required.

Airspace Class D: IFR and VFR are permitted; ATC service for all. IFR is separated from IFR and receives traffic information on VFR; VFR receives traffic information on all flights; clearance and radio communication are required.

Airspace Class E: IFR and VFR are permitted; ATC service and separation only for IFR (IFR separated from IFR). VFR does not normally receive ATC service, traffic information "as far as practical"; IFR requires clearance and radio communication, VFR not mandatory.

Airspace Class F (Advisory Airspace): IFR and VFR are permitted; participating IFR flights receive an Air Traffic Advisory Service, all flights can receive Flight Information Service (FIS); ATC clearance is not required (radio communication mandatory for participating IFR).

Airspace class G: Uncontrolled airspace according to SERA; IFR and VFR are generally permitted, there is no ATC control service and no separation; flights receive flight information service (FIS) where possible or on request. For IFR outside controlled airspace, the requirements of SERA.5025 apply (e.g., radio communication is only mandatory in areas/routes specified by the authorities). In...

Observer who monitors the airspace to assist the remote pilot in avoiding conflicts. In STS-02, the use of AOs influences, among other things, the maximum permissible range.

Service for providing aeronautical information/data necessary for the safety, regularity, and efficiency of aviation (e.g., NOTAM, AIP).

Altitude relative to mean sea level. Often used in aviation for airspace and obstacle reference and can differ significantly from AGL.

Organization that provides air traffic control or air navigation services (e.g., air traffic control, flight information, navigation services). In U-Space, coordination and data exchange between ANSP and USSP are regulated.

SORA indicator for air risk (collision risk with manned traffic) within the planned volume of operations. The initial ARC can be reduced through strategic and tactical measures (residual ARC).

Part of ATM responsible for sequencing/coordination in controlled airspace. In U-space airspaces within controlled airspace, coordinated procedures (e.g., dynamic airspace configuration) are crucial.

All functions and services for the safe, orderly, and efficient handling of air traffic (including ATC, airspace, and flow management). UAS integration (e.g., U-Space/UTM) must take into account interfaces with ATM.

Airspace area around an aerodrome with special traffic rules/procedures. For UAS operations, the ATZ environment is particularly relevant in risk assessment (e.g., ARC).

UAS that were placed on the market without EU class marking (e.g., before the relevant transition periods). Operation is still possible in the Open category, but only under restricted conditions (depending on mass/mode of operation).

Registration requirement for UAS operators under EU/national law; in Germany, the LBA assigns a UAS operator number (eID) after registration, which is entered into remote ID systems, among other places.

Formal declaration by the operator to the competent authority that a planned operation meets all the conditions of a standard scenario (STS). This allows the operation to start without individual approval (provided there are no additional national requirements).

Official approval for a specific operation in the Specific Category, usually based on a risk analysis (e.g., SORA) and an operations manual/procedure package.

Operation beyond visual line of sight. BVLOS is typically only permitted in the EU in the Specific Category (e.g., STS-02, PDRA, or SORA-based approval).

EU class designation for very light UAS (under 250 g MTOM) with specific technical requirements, including limited maximum speed and altitude restrictions.

EU class designation for UAS intended for Open A1 and required to meet technical requirements for safety, remote ID, geo-awareness, and other aspects (details in 2019/945).

EU class rating for UAS that can be used for Open A2, among other things, provided that additional operational and qualification requirements are met.

Communication link between UAS and ground/control station for transmitting control commands and telemetry. The reliability and latency of the C2 link are important safety factors, especially for BVLOS.

EU-Klassenkennzeichnung für größere UAS (u. a. bis 25 kg MTOM, max. charakteristische Abmessung < 3 m), typischerweise für Open A3 und bestimmte Specific-Szenarien.

EU class rating for UAS up to 25 kg MTOM without highly automated flight modes (except stabilization) and with requirements for operation and lost link behavior, among other things.

EU class rating for UAS intended for operation under STS-01 (Specific Category) and meeting additional technical requirements for this purpose.

EU class rating for UAS intended for operation in accordance with STS-02 (Specific Category) and which meet additional technical requirements for this purpose.

Marking indicating that a product meets EU conformity requirements. For UAS classes C0–C6, conformity assessment in accordance with 2019/945 is part of the process of placing the product on the market.

Provider (possibly designated as a "single CISP") that provides common information services—i.e., static and dynamic data required by USSPs and other actors for the provision of U-space services.

Data package for a U-space airspace, e.g., boundaries of the U-space airspace, requirements, relevant UAS geozones, and static/dynamic restrictions. It enables non-discriminatory access to U-space services.

Optional U-Space service that detects/warns of deviations from the issued UAS flight authorization in real time and informs the operator of non-compliance.

Structured description of the planned UAS operation (purpose, environment, airspace, procedures, roles, technology, emergency processes). In SORA, the ConOps description forms the basis for all further risk steps.

Area on the ground where the operator effectively controls access by unauthorized persons (e.g., barriers, security personnel). It is a central element in STS and in SORA tables for GRC determination.

A CTR (Control Zone) is controlled airspace extending from the ground to a specified upper limit, which usually protects one or more airports and approach and departure procedures.

Requirements for accuracy, timeliness, and delay of data exchanged in U-Space processes. These parameters are critical for safety, e.g., for conflict management and authorization.

In addition to safety, privacy/data protection must be considered as a separate risk dimension (e.g., cameras/sensors). EU UAS regulations point out that additional national/EU requirements must be observed.

Ability/systems to detect other traffic and obstacles and avoid conflicts – as a technical supplement/alternative to "see and avoid," particularly relevant for BVLOS.

Deutsche WindGuard is a German service provider (including for the wind energy industry) offering comprehensive measurement and assessment services, including noise measurement in accordance with applicable standards. In addition, the portfolio has been expanded to include inspections using drones (e.g., on wind turbines).

The DFS provides information and services relating to drone operation (including information on airspace use and references to DIPUL/apps). Important for operators in terms of airspace and safety.

German platform for information on UAS operations, including the publication/display of geographical areas (geo-zones) and government services. It serves as a central source for official UAS airspace information in Germany.

Function that transmits certain identification and position data by radio at regular intervals during flight (including operator registration number, position/speed/track of the drone). In the EU, requirements are defined in Delegated Regulation 2019/945.

DME (Distance Measuring Equipment) is a radio navigation aid for measuring the distance (slant range) between an aircraft and a ground station by measuring the transit time of pulses; it provides distance but not direction.

Collective term for counter-UAS measures designed to influence or stop a drone after detection (e.g., warning/forcing away, geofencing enforcement, GNSS/link jamming, takeover/mitigation, nets/interception drones, or other means of neutralization) – heavily regulated by law and dependent on the context of use. Learn more about drone defense.

Methods and systems for detecting and tracking unmanned aerial vehicles (UAS)—e.g., via radar, radio direction finding/RF analysis, optics/IR, acoustics, or multisensor fusion—with the aim of generating a situational picture and identification (if possible). Learn more about drone detection.

Procedure for dynamically configuring areas for U-Space/ATC within controlled airspace so that UAS and manned traffic remain safely segregated/coordinated.

EU Aviation Safety Agency, which supports and coordinates regulations, AMC/GM, guidance, and concepts for UAS/U-space, among other things.

Consolidated presentation of the U-Space Regulation (EU) 2021/664 and related materials, as a reference for requirements for U-Space airspaces, USSP/CISP, and services.

Consolidated "Easy Access" version of the relevant EU rules (including 2019/947, 2019/945) including AMC/GM, which serves as a practical reference for operators and authorities.

Collective term for technologies that make an aircraft electronically "visible" (e.g., ADS-B, FLARM, Remote ID). SORA cites increased detectability as a recommended risk mitigation measure.

Additional proof of competence for certain operations in Open A2 (e.g., closer to uninvolved persons). It builds on A1/A3 and typically includes additional theory and practical self-declaration.

EU-wide recognized proof of basic remote piloting skills for the Open category. In Germany, the online training/test is provided by the LBA, among others.

Operation with extended line of sight, in which, for example, observers ensure direct visibility of the UAS and pass on information to the remote pilot. EVLOS is regulated differently depending on national implementation.

Terms for failure concepts: Fail-safe aims to achieve a safe state in the event of errors (e.g., controlled landing), while fail-operational aims to continue operation despite errors with sufficient safety. The specific requirement depends on the operational risk.

Person who controls the UAS flight or who has direct responsibility for the safe execution of the operation, including compliance with operating limits, airspace rules, and procedures.

FLARM is a short-range collision warning and traffic awareness system (primarily for gliders/general aviation) that determines its own position and altitude (GNSS + barometric), transmits this information via radio, and detects and warns of conflicts with other FLARM participants based on a movement forecast.

System/function that terminates the flight in a targeted manner in order to limit risks (e.g., shutdown of propulsion, defined termination logic). Use and permissibility are highly dependent on the operating concept and risk analysis.

In SORA, the space in which the UAS is permitted to move as planned during normal operations. It is defined in the ConOps and is part of the operational volume.

European GNSS, operated under an EU program. For UAS, Galileo—like other GNSS systems—can provide positioning and timing data for navigation and tracking, among other things.

Function that informs the remote pilot/operator about airspace restrictions or UAS geozones and typically warns them before the drone flies into a restricted area.

U-Space service that provides UAS operators with up-to-date information on airspace restrictions and UAS geozones, published as part of the Common Information Services.

Technical restriction that automatically prevents or restricts flying into defined airspaces/geo-zones (e.g., through software limits). Geofencing is one possible implementation of geo-awareness.

Collective term for satellite-based navigation systems (e.g., GPS, Galileo) that provide position/time data. GNSS is the basis for many UAS navigation and monitoring functions.

SORA metric for ground risk—i.e., the risk of a person on the ground being struck by the UAS in the event of loss of control. The starting point is the "intrinsic" GRC, which can be reduced to a "final" GRC through mitigation measures.

Additional area around the operational volume that is taken into account in ground risk assessment (GRC). Among other things, it is intended to cover drift, errors, and unlikely individual events (e.g., 1:1 rule: buffer at least as large as flight altitude).

Terms from image processing/inspection: Bright field means that directly reflected light enters the camera (areas appear bright, surface structure appears rather "smooth"). Dark field uses flat illumination/geometry so that only scattered light (e.g., at edges, particles, defects) enters the camera—the background remains dark...

Standard operating limit in the open category: maximum flight altitude typically up to 120 m above the nearest point on the earth's surface, unless exceptions/geozone regulations apply.

"HX" indicates airspace that is temporarily effective (not permanently active). Before entering, the status should be checked, e.g., via FIS/INFO/TWR/ATIS; without checking the status, the airspace should be treated as active, and standby listening is also required.

Ability for U-Space actors (USSP, CISP, authorities, ANSP, operators) to exchange data via standardized, open protocols to enable safe and scalable UAS operations.

Provision of a product for initial distribution/use on the EU market. Relevant for UAS because class labeling and conformity requirements are linked to placing on the market.

Intentional or unintentional interference with radio signals (e.g., GNSS or C2-Link), which can cause loss of position/control. Robustness against interference is relevant in risk analyses.

C0–C6 marking on the UAS, confirming that the product meets defined EU requirements for design/manufacturing and may be used in certain operating scenarios.

Predefined procedures for controlling deviations or malfunctions (e.g., return-to-home, manual takeover, landing at a defined location). In SORA, they are part of the safety argumentation.

In SORA, the additional space required to keep the UAS safe in the event of a malfunction/deviation by means of contingency procedures (e.g., return-to-home, landing at a defined location).

Abbreviation for critical infrastructure: organizations/facilities whose failure or impairment could cause significant supply bottlenecks, security problems, or other serious consequences for the state and society.

Term for infrastructures and services of essential importance (e.g., energy, water, health, IT/telecommunications, transport/traffic). In Germany, the classification is specified in detail by legal regulations and thresholds (sectors/facilities that provide a "critical service" to the general public). More about drone defense & drone detection in critical...

Measurement and evaluation of noise (sound) caused by drones – typically as sound emission from the UAS (at the source) and/or sound immission at the point of impact (e.g., residential areas). Depending on the objective (certification, approval, acceptance study, comparison of operating profiles), the measurement setup, characteristic values, and evaluation are determined; in the European context, classification can also be carried out in...

Situation in which the C2 connection between the remote pilot/ground station and the UAS fails or becomes unreliable. UAS must have predefined lost link procedures/behaviors for this (e.g., return, landing, flight termination).

Optional operator certificate in the Specific Category. Depending on the privileges granted, a LUC may allow certain operations to be approved independently (e.g., without requiring an official operating permit each time).

Assessment that a Member State must carry out when designating U-space airspace in order to establish appropriate requirements, restrictions, and service obligations.

Refers to a gathering where the density is so high that individuals cannot quickly remove themselves in case of danger. Overflights are prohibited in the Open category.

SSR transponder mode that transmits only a four-digit identification code (squawk/SSR code) in response to interrogations.

SSR transponder mode that reports the barometric pressure altitude (typically in 100-ft increments) in addition to the identification code.

Mode N is a concept for a ground-based positioning/navigation system (A-PNT) that can supplement GNSS or partially replace it in the event of a failure, while also being more robust against spoofing/jamming. European CNS roadmaps describe Mode N as a "next-generation" ground-based positioning system.

SSR Mode S (Mode Select) allows selective interrogation of an aircraft using a unique 24-bit ICAO address and also supports data transmission (e.g., aircraft identification). ADS-B on 1090 MHz is typically transmitted as "Mode S Extended Squitter."

Maximum takeoff mass of a UAS including payload, as defined by the manufacturer. MTOM is relevant for classification, operating limits, and risk assessments, among other things.

National authority that, among other things, approves/monitors UAS operations (specific/certified), registers operators, and issues certificates of competence (distributed differently depending on the country).

An NDB (Non-Directional Beacon) is a radio transmitter in the LF/MF range that emits a signal of equal strength in all directions; with ADF receivers on board, the direction (bearing) to the NDB can be determined.

U-Space service that provides and distributes, among other things, the identity of UAS operators and the position and flight vector of UAS (even in contingency situations) to support situational awareness and coordination.

Official notification regarding the establishment, status, or change of aviation-related facilities, services, procedures, or hazards, the timely knowledge of which is essential for flight operations.

Procedures for situations that can no longer be controlled by contingency measures or pose an immediate serious danger (e.g., "land as soon as possible," flight termination).

Additional load on the UAS (e.g., camera, sensors, delivery goods) that affects mass, aerodynamics, and energy values and can therefore influence safety and approval requirements.

EU operating category for low-risk UAS operations. It is generally possible without prior operating approval, provided that, among other things, the operating limits (e.g., visual flight, altitude limit, distances) and class specifications are complied with.

In SORA, the area that must be technically "included" for safe operation. It consists of flight geography plus contingency volume.

Specific security objective in SORA (e.g., relating to technology, operations, people, organization) that must be fulfilled and verified according to SAIL with a defined integrity and assurance level.

Predefined risk analysis (AMC to Art. 11 of Regulation 2019/947) for certain types of operations. The operator can apply for approval based on the PDRA without having to create a complete individual SORA from scratch—provided that all framework conditions are met.

For SORA/AMC, "populated area" is understood in context as "congested area": an area in a city/town/settlement that is primarily used for residential, commercial, or recreational purposes.

UAS manufactured by an individual for personal use and not "placed on the market." Different/sometimes stricter operating conditions apply to such UAS in the EU (e.g., often Open A3 or Specific based on a risk approach).

Retrofit module designed to meet EU requirements for direct remote identification (including serial number, broadcast of relevant data via openly documented protocol).

Airspace that is reserved for specific purposes, thereby restricting its use by other traffic. In SORA/PDRA, reserved/segregated airspace can be part of air risk mitigation.

The Air Risk Class (ARC) remaining after applying strategic mitigation measures. Together with the final GRC, it determines the resulting SAIL.

An RMZ (Radio Mandatory Zone) is an airspace of defined size in which suitable radio equipment must be carried and continuous listening readiness or, if necessary, two-way radio communication on the specified frequency must be ensured (according to national regulations).

ICAO term for UAS in which a remote pilot actively controls the aircraft via remote control (not fully autonomous). In many contexts, RPAS is understood as a subset of UAS.

In the SORA context: Area outside a "populated area" and outside the Aerodrome Traffic Zone (ATZ) of an airport.

SORA outcome level (I–VI), which is determined from the final GRC and residual ARC. It specifies how robust evidence/OSOs (Operational Safety Objectives) must be implemented and documented.

Protection against deliberate actions (e.g., unauthorized access, jamming, spoofing). Security can influence safety and must therefore be taken into account in the U-Space/SORA environment.

Principle of collision avoidance through active visual search for conflicting traffic, provided that visual flight conditions exist. For UAS, this is supplemented by remote pilot/observer and/or technical means, depending on the operation.

Airspace in which UAS operations are spatially/temporarily separated from other (especially manned) traffic. This can greatly reduce the risk of air collisions (e.g., ARC-a).

Management systems for identifying, assessing, and minimizing safety risks (and security vulnerabilities with safety impact). For USSP and (single) CISP, such systems are planned within the U-Space framework.

Research/funding project ("Scalable drone communication systems for U-Space areas") with the aim of defining robust 4G/5G-based communication requirements for drone operation and testing them in practice in U-Space real-world laboratories (including comparison with commercial systems and integration of a USSP). Learn more

Risk assessment methodology for operations in the Specific Category. It structures the assessment of ground and air risks and derives the necessary mitigation measures and safety objectives from this.

SORA 2.5 (Specific Operations Risk Assessment) is the risk-based methodology developed by JARUS for assessing and deriving safety requirements for UAS operations in the "specific" category. EASA has integrated SORA 2.5 into AMC/GM to VO (EU) 2019/947 (ED Decision 2025/018/R).

Measures that reduce the likelihood of encounters with manned traffic (e.g., operation during times/in locations with low traffic density, temporarily segregated airspace). They can reduce the ARC.

Measures that support safe separation in the event of an encounter (e.g., DAA systems, cooperative electronic systems, or procedures). They are linked to TMPR/robustness.

EU operating category for operations with a higher risk than "Open." It typically requires an operating permit, a declaration (e.g., for STS), or a LUC—based on a risk analysis (e.g., SORA/PDRA).

Deception of navigation/position signals (e.g., GNSS), causing the system to process incorrect position data. Relevant security/safety risk, especially in BVLOS/high automation.

Predefined operating scenario described throughout the EU in the Specific Category. If an operator fulfills all conditions, they can submit a declaration instead of applying for an individual operating permit.

European standard scenario for VLOS operations over a controlled ground area, which may also be located in a populated area. Typically requires a UAS with C5 class designation.

European standard scenario for BVLOS operations over a controlled ground area in a sparsely populated area; different range conditions apply with/without an airspace observer. Typically requires a UAS with C6 class designation.

UAS that is physically connected to the ground via a tether/cable. Depending on the design, this can reduce certain risks (e.g., limiting the area of operation); requirements arise from the mission concept and regulations.

Performance requirements for tactical mitigation measures against air collision risks (e.g., detect-and-avoid, cooperative systems, procedures). The TMPR depends on the residual ARC.

A TMZ (Transponder Mandatory Zone) is an airspace of defined extent in which the carriage and operation of SSR transponders (Mode A/C or Mode S) is mandatory, unless alternative requirements apply.

U-Space service that warns or informs UAS operators about other air traffic in the vicinity of their UAS in order to avoid conflicts.

A transponder is an onboard radio device that automatically responds to SSR queries from ground radar or other systems and, depending on the mode, transmits identity code, altitude, and other data to identify and monitor aircraft.

The transponder code (SSR code/squawk) is a four-digit octal code that is set in the transponder and is used for identification/handling by ATC. Standard emergency codes are 7700 (emergency), 7600 (comms failure), and 7500 (unlawful interference).

Airspace designated by an EU Member State in certain UAS geozones, the use of which is subject to the use of defined U-space services. The designation must be supported by, among other things, an airspace risk analysis.

A real-world testing ground ("living lab") for U-Space, where U-Space services, processes, and the interaction between drone traffic management (U-Space/USSP) and traditional air traffic control are tested and validated under realistic conditions (e.g., in port/industrial areas or via virtualization). Learn more about the Hatten UAS German Flight Center.

A U‑Space service is a service provided in designated U‑Space airspace to support safe and efficient UAS operations. The EU regulation specifies mandatory U‑Space services such as network identification, geo‑awareness, traffic information, and UAS flight authorization, which are offered by certified U‑Space service providers (USSPs).

Service levels from SESAR U-Space development: U1 (Foundation: e-registration/e-identification/geofencing), U2 (Initial: flight planning/clearance, tracking, ATC interface), U3 (Advanced: conflict support/more automation), U4 (Full: highly automated operations in very dense environments).

EU technical term for an unmanned aircraft (without passengers on board) that can be operated remotely or automatically. In EU texts, "UA"/"unmanned aircraft" is often used to refer to the platform.

Refers to the entire system consisting of an unmanned aircraft (UA), control segment (e.g., ground station), and the components necessary for operation (e.g., data link). In EU regulations, "UAS" is the central collective term for drone operation. Learn more about UAS at b.r.m.

U-space service that coordinates UAS flight authorizations in U-space and ensures that authorized UAS operations within the U-space area in question do not collide with each other in terms of space and time.

Natural or legal person who conducts or commissions UAS operations and is responsible for organizing the operation (e.g., procedures, personnel, maintenance).

An area designated by a state with special rules for UAS (e.g., prohibitions, altitude limits, technical requirements, or licensing requirements) to protect safety, security, privacy, or the environment.

The unmanned aerial vehicle itself—i.e., the flying part of the UAS. Colloquially, UAV is often used synonymously with "drone," but technically it refers only to the platform without the ground/control segment. Learn more about UAVs at b.r.m.

Open subcategory for very low-risk flights "close to people." Flying over uninvolved persons may be permitted depending on the UAS class; flying over crowds of people is prohibited.

Open subcategory for flights "close to people" with stricter requirements for UAS and qualifications. Typical requirements include defined minimum distances from uninvolved persons and additional remote pilot skills.

Open subcategory for flights "away from people." Operation is only permitted in areas where no uninvolved persons are endangered and, as a rule, at a considerable distance from built-up/public areas.

Certified provider that provides U-Space services for UAS operators (at least the mandatory services) and meets requirements for management systems, data quality, interoperability, etc. Learn more about b.r.m. as a U-Space service provider

ICAO concept for the (near) real-time organization, coordination, and management of many UAS operations—especially in low airspace and also for BVLOS—through digital services and cooperation between authorities/ANSPs/industry.

Operation in which the remote pilot (or an observer in accordance with regulations) can see the UAS directly with their own eyes throughout the entire flight in order to monitor its flight position and surroundings and avoid collisions.

VOR (VHF Omnidirectional Radio Range) is a VHF radio navigation system that provides bearing information: the aircraft can use the VOR signal to determine the magnetic bearing (radial) to/from the ground station.

Optional U-Space service that supports UAS operators in planning and execution with weather information, thereby also improving the quality of other U-Space services.

EU operating category for high-risk operations. In principle, certification of UAS, operators, and (depending on the case) licensing of remote pilots are planned.