Introduction to drone technology

What is flying there, and what can it do?

In this lesson you will learn how a drone works technically, which airframe types exist and how the legal class logic is structured.

In detail:

  • Airframe types. How can the various drone types be categorised and what makes each of them distinctive
  • Classification. Which device classes and flight categories exist, and which class may be operated in which way??
  • Other technical systems. How UAVs are controlled and which levels of autonomy exist.

Commercial UAV operations – distinguishing operator and remote pilot 

First of all, some context on the commercial use of UAVs. 

Within a company the two roles are held by different parties. The company is the operator and carries the registration obligation and the insurance obligation. The employee is the remote pilot and carries the qualification obligation. In the event of an incident the operator is approached first, just as the registered keeper is approached first in the case of a vehicle. 

A registration number, the e-ID, applies to the operator, not to an individual device. A company can operate any number of drones under the same e-ID.

UAV airframe types

When we hear the term drone, we often think of the typical small quadcopter, a small aircraft with four rotors. There are, however, many other airframe types:

Multicopter - multirotor
Several lift-generating rotors in one plane. From tricopter to octocopter X8. More rotors mean more payload and greater failure tolerance, but shorter flight time.
Fixed-wing
Wings instead of rotors. Cannot hover, needs a runway or a hand launch. Achieves many times the range of a multirotor. The flying-wing subvariant has a low radar cross-section.
VTOL hybrid
Takes off vertically like a multirotor, then continues in wing-borne flight. Combines the advantages of both at the cost of complexity and mass.
FPV racer / freestyle
Small propellers, often self-built, controlled through video goggles. Extremely agile and fast, usually without satellite navigation and without geo-awareness. The most relevant misuse platform available on the civil market.
Tethered drone
Power supplied through a cable, endurance practically unlimited, altitude limited by the cable. Used for site surveillance.
Lighter than air
Tethered balloon, airship, aerostat. Very long endurance, hardly any manoeuvrability. The radar picture looks completely different from that of a multirotor.

Besides the airframe type, further technical aspects and functions determine how UAVs are used:

Propulsion ▾
Small systems use brushless electric motors with speed controllers and fixed propellers. Control is achieved solely through the rotational speed of the individual motors; there are no movable control surfaces. Larger systems use combustion engines or turbines. Trace: the blade passage frequency of the propellers produces a characteristic noise pattern. This is the basis of acoustic detection.
Power ▾
Lithium-polymer or lithium-ion batteries. They determine the flight time and thus the window during which a device can remain over a site. Typical figures are between 20 and 45 minutes for multirotors. Energy density is the limiting factor for the entire category.
Flight control ▾
A flight controller processes gyroscope, accelerometer, barometric and magnetic field values and keeps the device in the air. Important: this control works entirely without satellite navigation. A device without GNSS is not unable to fly, it is merely harder to fly.
Navigation and radio links ▾
Civil satellite navigation relies primarily on GPS. Geo-awareness and the return-to-home function build on it. There are up to four separate radio links: control, video, telemetry and satellite reception. The downlink carrying video is often the stronger signal source. Every transmitting link can be found passively.
Payload ▾
Camera, zoom optics, thermal imaging, laser scanner, multispectral sensor, loudspeaker, release mechanism. It is the payload that determines the actual damage potential, not the size of the device.
Geo-awareness ▾

Geo-awareness is a technical function in drones that actively warns the pilot before the aircraft enters a restricted or prohibited geographical zone (airports, for example). Combined with geo-fencing, entry is even blocked automatically.

Geo-fencing ▾

This is how geo-fencing blocks entry
Virtual walls: the drone stops in mid-air as soon as it reaches the boundary of a no-fly zone and does not fly any further into it.
Take-off lock: if the drone is already inside a prohibited zone, the motors are locked. Taking off is impossible.
Automatic landing: if the status of a zone changes to "restricted" during the flight, the drone automatically initiates a landing or a return to the take-off point (return-to-home).

Levels of autonomy

Four levels make the difference between a detectable and an undetectable approach. From level three onwards, any detection based on radio fails.

Level 1: manually controlled ▾
Continuous radio link, pilot within visual line of sight or using a video image. Fully findable by radio.
Level 2: assisted ▾
Position hold, altitude hold, return-to-home function, still a continuous link. Likewise findable by radio.
Level 3: waypoint flight ▾
The route is programmed in advance and the device flies it. The radio link can be switched off during the flight or can drop out without the flight ending. From this point on, any detection based on radio fails.
Level 4: autonomous with on-board logic ▾
Target recognition or navigation without a satellite signal by means of image matching. Neither radio jamming nor navigation jamming has any effect.

Classification of UAVs

To assess UAVs and their use in legal terms, you need to understand how the devices are classified and how they are operated.

Delegated Regulation (EU) 2019/945 sets out the technical and product-specific requirements for UAVs in the European Union. 

Two class categories play an important role here and are often confused. The C class looks at the aircraft. The A subcategory is the way in which it is operated. 

The device: C0 to C6
Follows from the characteristics of the device, shown as a label on the device. Cannot be changed. The class label is a circle containing a digit, not the CE mark.
The flight: A1, A2, A3
Determined by the remote pilot before each operation. Can be changed. Describes the mode of operation, not the device.
The person: proof of competency
Issued by the authority after an examination. Can be acquired. A remote pilot certificate qualifies the person but does not open up a mode of operation that the device does not support.

2.6 The class labels C0 to C6

Legal basis: Delegated Regulation (EU) 2019/945. Since 1 January 2024, devices newly placed on the market must carry a label.

Class Maximum take-off mass Further characteristics Remote identification Geo-awareness
C0 under 250 g max. 19 m/s, max. 120 m altitude, max. 24 V no no
C1 under 900 g, alternatively impact energy below 80 J max. 19 m/s, altitude limitation, link loss management, unique serial number, battery warning, lighting, max. 85 dB yes yes
C2 under 4 kg additionally a secured data link and a low-speed mode, max. 48 V yes yes
C3 under 25 kg as C2, no low-speed mode required yes yes
C4 under 25 kg no automatic or autonomous flight permitted, no electronic requirements no no
C5 as C3, modified altitude limitation lifted yes not mandatory
C6 as C3, modified, propulsion may also be non-electric max. 50 m/s horizontally, programmable flight path, autonomous flight that can be switched off yes not mandatory

Note: C5 and C6 may be used only in the specific category or in the standard scenarios. The “specific category” applies to operations with a higher risk that no longer fall under the simple hobby rules.

2.7 The subcategories A1, A2 and A3

Legal basis: Implementing Regulation (EU) 2019/947. They describe the mode of operation, not the device.

↔ Table scrolls sideways

Criterion A1 A2 A3
Basic idea Operation close to people Operation at a safe distance from people Operation far from people
Distance from uninvolved persons C0: overflight permitted. C1: approach permitted, deliberate overflight not 30 m horizontally, 5 m in low-speed mode at a maximum of 3 m/s no uninvolved persons in the operating area
Distance from residential, commercial, industrial and recreational areas none none 150 m horizontally
Assemblies of people prohibited prohibited prohibited
Proof of competency C0 none, C1: A1/A3 A1/A3 plus remote pilot certificate A2 A1/A3

Rule of thumb for A1 and A2: the horizontal distance from an uninvolved person should be at least equal to the flight altitude. A device at 40 metres needs 40 metres of clearance on the ground, because in the event of a failure it does not fall straight down.

Interactive matrix: classes & subcategories

Choose a device (class) and a mode of operation (subcategory). The matrix shows whether the combination is permitted, with the rule and an example.

1. Choose a device (class)

2. Choose a mode of operation (subcategory)

Please choose a device and a mode of operation on the left.

Things to remember: A3 always works (the most restrictive mode of operation). A1 and A2 are privileges of the device, not of the pilot – without a matching label, every device above 250 g stays permanently in A3.

Further legal obligations arising from the operation of UAVs:

Registration as a UAS operator ▾
Required from 250 grams upwards, or where the device weighs under 250 grams and carries a camera. Toy drones for children under 14 are exempt. The result is the e-ID. The fee is 20 euros for natural persons and 50 euros for legal persons.
Proof of competency for the remote pilot ▾
No proof is required for devices under 250 grams or in class C0. From 250 grams upwards, the EU proof of competency A1/A3 applies, valid for five years. For A2 the A2 remote pilot certificate is additionally required, with a theory examination of 30 questions, passed from 75 per cent. Minimum age 16.
Third-party liability insurance ▾
Mandatory for every drone, regardless of weight, class and type of use, private as well as commercial. The obligation attaches to the keeper, that is, to the company. Private policies frequently exclude drones.
Rule to remember ▾
Registration from 250 grams or with a camera. Proof of competency from 250 grams. Insurance from the very first gram.

The limits of the class logic

Consider a self-built FPV device of around 500 grams with no label, no registration, no remote identification and no satellite navigation. Formally this would be an A3 device. In practice it sits outside any form of compliance:

  • Without a class label, none of the minimum technical requirements apply.
  • Without geo-awareness, geo-zones have no effect and the device warns of nothing.
  • Without remote identification, cooperative detection does not work.
  • Without registration, there is no route from the device to the keeper.
  • Without satellite navigation, it remains able to fly even when the signal is jammed.

The closing statement of this lesson: the entire class logic, every label, every proof of competency, every registration describes the compliant user. It does not describe the attacker. Anyone intruding deliberately picks exactly those devices that none of these rules covers. That is precisely why a site needs detection and not just legal knowledge.

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Lesson 3 — Legal options for civil companies

Now that you know what is flying there, this lesson answers the decisive question: what are you allowed to do when someone else's drone is flying over your company? The answer is clearer than many expect, and it has direct consequences for your room for manoeuvre.

What awaits you

  • Who is responsible? Why there is no permanent monitoring of the airspace above your site and what that means for your role.
  • The protection your site already has. The 100-metre restricted area under Section 21h of the German Air Traffic Regulations and why you are the consenting body.
  • The line between detection and defence. Why interception, jamming, spoofing and shooting a drone down are prohibited for private parties without exception.
  • What is actually allowed. Detecting, documenting, reporting, preparing structurally and withholding consent.
  • Claims & reporting route. Which rights you have against a drone operator and how a usable report comes about.

Core statement of this lesson: “There is no right of self-defence against drones that entitles a company to act. On this question, your own property ends at the ground.”