Wieso eine EU Drohnen-Verordnung?

Neben dem reinen Freizeitvergnügen werden unbemannte Fluggeräte immer mehr für gewerbliche und behördliche Zwecke entwickelt und genutzt. Um einen sicheren Betrieb der Drohnen zu gewährleisten und eine Gefährdung der bemannten Luftfahrt auszuschließen, mussten Regularien für den Einsatz geschaffen werden. Im Jahr 2019 wurde eine europaweit einheitliche Regelung für alle EU-Länder beschlossen, die bereits am 01. Juli 2020 in Kraft treten sollte. Aufgrund der Corona-Pandemie wurde der Termin jedoch auf den 01.01.2021 verschoben.

Darf ich meine nicht klassifizierte Drohne auch nach dem 1. Januar 2021 noch weiter fliegen?

Ja, Sie dürfen die Drohne definitiv noch weiter fliegen. Dafür gelten spezielle Übergangsregelungen, die das sicherstellen. Je nach Gewicht der Drohne ist es abhängig davon, in welcher Kategorie der offenen Klasse Sie fliegen dürfen. Es kann aber erforderlich werden, dass Sie bei einer der vom LBA anerkannten Stellen einen Kenntnisnachweis bzw. jetzt neu einen Kompetenznachweis erwerben müssen.

Was bedeuten kleiner und großer Drohnenführerschein?

Der Kenntnisnachweis nach §21e der Luftverkehrsordnung wird auch als kleiner Drohnenführerschein oder Modellflugführerschein bezeichnet. Der Kenntnisnachweis nach §21d der Luftverkehrsordnung wird auch als großer Drohnenführerschein bezeichnet.

Was passiert mit meinem alten nationalen Drohnenführerschein?

Laut den EU Drohnengesetzen bleiben sowohl der Drohnenführerschein, als auch der Kenntnisnachweis noch ein Jahr gültig. Danach werden der Drohnenführerschein und der Kenntnisnachweis durch den EU-Kompetenznachweis A1/A3 bzw. das EU-Fernpiloten-Zeugnis A2 abgelöst. Die Kompetenznachweise können in der Regel an den vom Luftfahrt Bundesamt anerkannten Stellen nach einem Online-Lehrgang erworben werden.

Welche Regeln gelten beim Hangfliegen?

Beim Hangfliegen mit Segelflugmodellen ist immer ein Abstand von max. 120 m zum nächstgelegenen Punkt auf der Erdoberfläche zu halten. Sollte das Modellsegelflugzeug inkl. Zuladung leichter als 10 kg (Maximum Take-Off Mass = MTOM) sein, so kann es auch in einem größeren Abstand zum Boden geflogen werden. Vorausgesetzt, dass zu keiner Zeit die Höhe über den Fernpiloten von 120 m überschritten wird.

Was ist unter privat hergestelltes UAS zu verstehen?

Der Hersteller muss nur dann eine Klassifizierung eines unbemannten Fluggerätes durchführen, wenn es sich um ein Komplettsystem mit allen erforderlichen Komponenten, wie Modell, Antrieb und Fernsteuerung handelt. Auch wenn das System als Bausatz geliefert wird und vom Anwender erst noch zusammengebaut werden muss. Wenn der Betreiber lediglich das Modell erwirbt und dann bestehende Fernsteuer- oder Antriebskomponenten nachrüstet, gilt das Modell als privat hergestellt.

The new EU drone regulation 2021

Updated: 16.05.2022 | Reading time: 20 minutes

_{This text is machine translated.}

A few years ago, model builders and electronics specialists began to develop very special model airplanes. The classic wings, which provided lift, were replaced by several propellers. These unmanned aerial vehicles were initially referred to as copters, with the number of propellers being given priority. The most common were quadro-copters with four propellers. However, there were already large hexa-copters with six or octo-copters with eight propellers.

In the meantime, however, the names of unmanned aerial systems have shifted more and more from copter to drone.

What was often ridiculed in the beginning has now developed into a gigantic market worldwide.

The technology has become better and better, allowing payloads and flight times to be increased. This has also led to an increase in commercial applications, which is why more and more people are interested in unmanned aerial vehicles.

And because prices have steadily become cheaper, the number of drones in operation has exploded within a very short space of time.

Drohne bei der Inspektion von Stromleitungen

Why an EU drone regulation?
A brief summary of the new EU drone laws
The three different operating categories
Subdivision of the open business category
Classification of unmanned aerial systems

Overview of possible applications
Operation of unmanned aerial vehicles without classification
Effects on existing models
Operation of model aircraft in accordance with the new EU regulation
Frequently asked questions about the EU drone regulation

Why an EU drone regulation?

In addition to purely recreational use, unmanned aircraft systems (UAS) are increasingly being developed and used for commercial and official purposes. In order to ensure the safe operation of drones and rule out any risk to manned aviation, regulations had to be created for their use. To this end, a wide range of legal regulations were enacted years ago at a national level.

This was followed in 2019 by a uniform European regulation for all EU countries, which was due to come into force on July 1, 2020. However, due to the coronavirus pandemic, the date was postponed to 01.01.2021.

The requirements of the EU Drone Regulation are set out in the two documents

Delegated Regulation (EU) 2019/945
Implementing Regulation (EU) 2019/947

are precisely defined.

The following regulations must also be observed:

Implementing Regulation (EU) 2020/746 with the postponements due to the coronavirus pandemic.
Implementing Regulation (EU) 2020/639 amending Implementing Regulation (EU) 2019/947.
Delegated Regulation (EU) 2020/1058 amending Delegated Regulation (EU) 2019/945
Implementing Regulation (EU) 2022/425 with current postponements

In addition to the aforementioned EU directives on drone regulations, there are also country-specific requirements that must also be observed and complied with.

Important notes

It's not just about drones!

Even though the term "drone regulation" is commonly used, the regulation applies to all unmanned aircraft systems (UAS). This means that all types of remote-controlled model aircraft or helicopters are also included and affected.

Quick and easy registration and certificate of competence A1/A3:

To the UAS operator registration »

To the EU Certificate of Competence A1/A3 »

Compulsory insurance

Insurance is still compulsory. The operation of an unmanned and remote-controlled aircraft is associated with certain risks that are often not covered by traditional liability insurance. It is therefore essential to take out suitable supplementary insurance. Even if operation is permitted without further conditions according to the Drone Ordinance.

The essentials of EU drone legislation briefly summarized

The most important facts about the new EU drone regulation:

Unmanned aerial systems (UAS) are divided into three different operating categories (open, special and subject to certification).
The open category is divided into the subcategories A1, A2 and A3.
The maximum permitted flight altitude will be increased from 100 m to 120 m.
Introduction of two new certificates of competence (class A1/A3 and A2) and the operator certificate (LUC certificate).
Adjustment of the weight limits.
Registration of remote pilots and sending of identification (electronic ID), depending on the class.
The minimum age for users is 16 years, although there are exceptions according to Implementing Regulation (EU) 2019/947, Article 9.
The EU Drone Regulation does not apply to remote-controlled aircraft intended exclusively for indoor use.

The three different operating categories

As unmanned flying objects come in different sizes and are used for a wide variety of tasks, operations have been divided into three categories:

No authorization is required, but user registration may be necessary.

The take-off mass must be less than 25 kg.

The model must be flown by sight.

Exception: An additional observer is used or the model is flown in "follow me mode".

The maximum permitted flight altitude must be observed.

A safe distance from people must be maintained and crowds of people must not be flown over.

Depending on the operational risk, there are minimum requirements, such as carrying a certificate of competence.
The special category is intended for applications that are not legally feasible in the open category.

The UAS operator must carry out a risk assessment before use.

Approval for operation is required if the user does not have an operator certificate (LUC certificate) with the necessary rights.

Alternatively, a declaration of operation can be submitted to the competent authority if the operation takes place in compliance with a defined standard scenario.
The category requiring approval or certification is intended for special applications in industry and transportation.

The necessary licenses and certification processes are required for both the UAS and the operator/crew.

Operation in the category requiring certification may be required if the risk assessment does not permit operation in the special category.

Subdivision of the open business category

The open operating category is divided into three sub-categories A1, A2 and A3. The distinctions relate, among other things, to flying in the vicinity of people.

In der offenen Katagorie unzulässig: Drohnenflüg über einer Menschenmenge

Absolutely prohibited in the open class: Flying over a crowd of people or uninvolved persons.

Subcategory A1:

In this subcategory, flying close to people is also possible. However, no crowds of people in the open air and no uninvolved persons may be flown over. Should this nevertheless happen, the overflight must be terminated as quickly as possible.

Subcategory A2:

When flying according to subcategory A2, a distance of at least 30 meters must be maintained from uninvolved persons. If flying in slow flight mode, the minimum distance may also be 5 meters.

Sub-category A3:

This category is intended for flying away from uninvolved people. No persons may be present in the entire flight area and a minimum distance of 150 m from industrial, commercial, residential and recreational areas must be maintained.

Classification of unmanned aerial systems

In addition to the operating categories, commercially manufactured and marketed drones and model aircraft are also divided into different drone classes (UAS classes). There are seven different classes from drone class C0 to C6, with the number representing a statement about the safety risk. The higher the number, the higher the risk.

Depending on which class the drone falls into, different requirements must be met for operation. We have summarized some of the most important points below:

The maximum take-off mass including battery and possible payload (MTOM = Maximum Take-Off Mass) must be less than 250 g.

The maximum speed in level flight must be less than 19 m/s (= 68.4 km/h).

The maximum achievable altitude is 120 m above the take-off point.

The model must be safely controllable by the remote pilot following the manufacturer's instructions.

The risk of injury during operation from sharp edges and propellers must be minimized as far as possible.

The model is only operated electrically.

In Follow Me mode, if available, the distance to the pilot must not exceed 50 m. In addition, the remote pilot must be able to regain control of the drone.

Instructions must be included which contain all relevant information and hazard warnings.
The maximum take-off mass (MTOM) must be less than 900 g. Alternatively, the impact energy must be less than 80 J in the event of an impact at terminal velocity.

The maximum speed in level flight must be less than 19 m/s (= 68.4 km/h).

The maximum achievable altitude is 120 m above the take-off point. Alternatively, it must be equipped with a system that limits the flight altitude to 120 m. In the case of adjustable systems, the operator must be informed of the current altitude during the flight.

The model must be safely controllable by the remote pilot who follows the manufacturer's instructions and is sufficiently qualified.

The UAS must be designed and built to withstand all loads during operation. The risk of injury during operation from sharp edges and propellers must be minimized as far as possible.

If the radio link is lost, it must be re-established automatically. Alternatively, the model must end the flight and land automatically if the transmitter signal is lost.

If the model is not a fixed-wing aircraft, the specified limit value for the sound power level must not be exceeded. The respective values must be indicated by the manufacturer on the UAS system and/or on the packaging.

The model is only operated electrically.

There must be a unique serial number, as well as direct remote identification and a geo-sensitization function.

The model must also be equipped with a low battery warning function and have position lights to distinguish it from a manned aircraft at night.

In Follow Me mode, if available, the distance to the pilot must not exceed 50 m. In addition, the pilot must be able to regain control of the drone.

The drone must be accompanied by instructions containing all relevant information and hazard warnings.
The maximum take-off mass including battery and possible payload (MTOM = Maximum Take-Off Mass) must be less than 4 kg.

The maximum achievable altitude is 120 m above the take-off point. Alternatively, it must be equipped with a system that limits the flight altitude to 120 m. In the case of adjustable systems, the operator must be informed of the current altitude during the flight.

The model must be safely controllable by the remote pilot who follows the manufacturer's instructions and is sufficiently qualified.

The UAS must be designed and built to withstand all loads during operation. The risk of injury during operation from sharp edges and propellers must be minimized as far as possible.

In the case of a tethered UAS, the maximum line length may be 50 m. The line must have sufficient tensile strength in accordance with the specifications.

If the radio link is lost, it must be re-established automatically if it is not a tethered UAS. Alternatively, the model must automatically terminate the flight and land if the transmitter signal is lost. Access to the steering and control functions must be secured against unauthorized access.

If the model is not a fixed-wing aircraft, the specified sound power level limit must not be exceeded. The respective values must be marked on the UAS and/or on the packaging. In addition, the UAS must be equipped with a slow flight mode with a maximum speed of 3 m/s above ground.

The remote-controlled model is operated exclusively electrically.

There must be a unique serial number, as well as direct remote identification and a geo-sensitization function.

The model must also be equipped with a low battery warning function and have position lights to distinguish it from a manned aircraft at night.

It must be accompanied by instructions containing all relevant information and hazard warnings.
The maximum take-off mass including battery and possible payload (MTOM = Maximum Take-Off Mass) must be less than 25 kg and the maximum characteristic dimension less than 3 m.

The maximum achievable altitude is 120 m above the take-off point. Alternatively, it must be equipped with a system that limits the flight altitude to 120 m. In the case of adjustable systems, the operator must be informed of the current altitude during the flight.

The model must be safely controllable by the remote pilot who follows the manufacturer's instructions and is sufficiently qualified.

In the case of a tethered UAS, the maximum line length may be 50 m. The line must have sufficient tensile strength in accordance with the specifications.

If the radio link is lost, it must be re-established automatically if it is not a tethered UAS. Alternatively, the model must automatically terminate the flight and land if the transmitter signal is lost.

If the model is not a fixed-wing aircraft, the specified sound power level limit must not be exceeded. The respective values must be marked on the UAS and/or on the packaging.

The remote-controlled model is only operated electrically.

There must be a unique serial number, as well as direct remote identification (if not tethered) and a geo-sensitization function.

Access to the control and monitoring functions must be secured against unauthorized access.

The remote-controlled model must also be equipped with a low battery warning function and have position lights to distinguish it from a manned aircraft at night.

It must be accompanied by instructions containing all relevant information and hazard warnings.
The maximum take-off mass including battery/fuel and possible payload (MTOM = Maximum Take-Off Mass) must be less than 25 kg.

The model must be safely controllable by the remote pilot following the manufacturer's instructions.

Apart from attitude stabilization and a fixed position of the flight controls in the event of loss of data connection, no automatic control modes may be present.

The model must be accompanied by instructions containing all relevant information and hazard warnings.
A class C5 UAS corresponds to a class C3 UAS, whereby the altitude limitation has been removed and the geo-sensitization function is not mandatory.

If it is not a fixed-wing aircraft and is not tethered, it is an aircraft.

The specific altitude information is continuously transmitted to the remote pilot.

If not tethered, the UAS must be equipped with an adjustable slow flight mode that limits the cruising speed to max. 5 m/s.

If the UAS is not tethered, the drone pilot must be able to deactivate the automatic flight control and flight guidance systems and manually force a descent without forward movement. There must also be a system in place to reduce the impact energy.

If not restrained, the remote pilot must be constantly informed of the quality of the control signals. If there is a risk that safe operation is no longer possible due to signal degradation or signal interruption, the remote pilot must be warned.

Note:

A class 3 UAS can be upgraded to a class 5 UAS with suitable additional parts. In this case, the additional parts must be marked with the C5 mark.
A class C6 UAS corresponds to a class C3 UAS, whereby the height limit has been lifted and the geo-sensitization function is not mandatory. In addition, not only electric drives may be used.

The maximum speed in level flight may not exceed 50 m/s (180 km/h).

During the flight, the remote pilot is provided with up-to-date information on the geographical position, speed and altitude.

An integrated system ensures that the horizontal and vertical limits of the previously defined and programmed operating space are adhered to.

It must be possible to program the flight path.

The remote pilot must be able to manually deactivate the automatic flight control and flight guidance systems in order to terminate the flight without violating the limits of the operating envelope.

The remote pilot must be constantly informed about the quality of the control signals. If there is a risk that safe operation is no longer possible due to signal degradation or signal interruption, the remote pilot must be warned.

Overview of possible applications

The different operating categories and drone classes now result in possible applications, which we have summarized in the following table. However, we have limited ourselves to the essential characteristics of the different classes and the relevant UAS classes.

Specification	C0	C1	C2	C3	C4
Weight/impact allergy	< 250 g	< 900 g/<80 J	< 4 kg	< 25 kg	< 25 kg
Max. Weight	19 m/s = 68 km/h	19 m/s = 68 km/h	-	-	-
Max. Flight altitude	120 m	120 m or adjustable height limit	120 m or adjustable height limit	120 m or adjustable height limit	120 m or depending on the model airfield
Technical requirements	Toy directive or <68 km/h, height limit	< 68 km/h, altitude limit, emergency landing in case of signal loss	Altitude limitation, emergency landing in case of signal loss, low-speed mode, predetermined breaking points	Altitude limitation, emergency landing in case of signal loss, low-speed mode, predetermined breaking points	No automatic control allowed
Registration of the remote pilot required	No or yes for camera drones	Yes	Yes	Yes	Yes
Competence of the remote pilot	Read operating instructions	Read operating instructions, EU certificate of competence A1/A3	Read operating instructions, EU certificate of competence A1/A3, remote pilot certificate A2	Read operating instructions, EU certificate of competence A1/A3	Read operating instructions, EU certificate of competence A1/A3
Remote identification required	No	Yes	Yes	Yes	No
Geo-sensitization required	No	Yes	Yes	Yes	No
Operation in the open category	A1 = Flight over people	A1 = Flight over people	A2 = Flight close to people, A3 = flight far away from people	A3 = Flight far away from people	A3 = Flight far away from people

Explanation of the table

Registration of the remote pilot

Every user or remote pilot of a UAS must be registered with the competent authority. Unless the aircraft is lighter than 250 g and has no sensors for recording personal data (camera). In Germany, the Federal Aviation Office (LBA) is responsible for registration. The authority then assigns the respective person an individual eID number. This number must be affixed to the model. This is mandatory from 01.01.2021. In order to give the many remote pilots sufficient time to register, the LBA has lifted the registration requirement in the "open" and "special" categories until the end of April 2021. However, signs with the name and address of the remote pilot must be attached to the models.

Professional competence of the remote pilot

If UAS of class C1 or higher are to be used, the user must obtain the EU certificate of competence. To this end, the competent authorities of the member states will set up online portals where users can familiarize themselves with the necessary content and also take the 40-question exam online. The Federal Aviation Authority responsible in Germany will activate the access points at the end of December 2020 and is expecting a very high demand at the beginning of January. The certificate of knowledge used in Germany to date is still valid until 31.12.2022 and entitles the holder to fly drones in the open class.

Remote identification

During remote identification, the ID number of the remote pilot, the serial number of the UAS, the time stamp, the geographical position, the altitude above the take-off point and other information are transmitted. The information can then be read out using a smartphone with a suitable app. There is still a transitional period until 31.12.2022 for the implementation of this regulation. From 01.01.2023, the regulation will be mandatory.

Geo-sensitization

Geo-sensitization or geo-awareness is a function in which the UAS automatically detects flight space boundaries. The drone pilot is warned so that they can take effective measures to prevent a violation of the boundaries.

Operation of unmanned aerial vehicles without classification

Even though the new EU drone regulation will be binding from January 1, 2021, drones and model aircraft that are not classified are still being sold and operated. The EU regulation makes clear statements here:
UAS types that were placed on the market before 01.01.2024 and are not classified can be operated in open category A1. Provided they weigh less than 250 g including payload. UAS types that weigh 250 g or more but are still lighter than 25 kg can be operated in open category A3.

Transitional regulation

According to the EU Drone Regulation, there is a transitional regulation for existing unmanned aircraft systems. The existing operating authorizations are valid for one year after 01.01.2021. The transitional regulation already came into force on 01.07.2020 and has a term of 30 months. Accordingly, the transitional period ends on 31.12.2022.

In accordance with this transitional regulation, unmanned aircraft with a take-off mass of less than 500 g can also fly in open class A1. However, if uninvolved persons are unexpectedly flown over, the overflight must be kept as short as possible.

Unmanned aircraft lighter than 2 kg may be operated in open class A2. The minimum distance to persons must be 50 m and the drone pilot must hold the EU certificate of competence A1/A3 and the EU remote pilot certificate A2.

Even without certification, drones may continue to be used after 01.01.2021 under certain conditions.

For a better overview, we have listed the different weight classes once again:

Data	Operation in the open class	EU certificate of competence A1/A3	EU Remote Pilot Certificate A2
Less than 250 g & max. 68 km/h	A1	No, but recommended	No
Less than 500 g	A1	Yes, from 01.01.2023	No
Less than 2 kg & closer than 150 m to residential or commercial areas	A2	Yes	Yes
Less than kg & at a distance of more than 150 m from residential or commercial areas	A3	Yes	No

Important note!

If a UAS with a maximum take-off mass (MTOM) of between 2 kg and less than 25 kg has to be used closer than 150 m to residential or commercial areas, this is only possible in the special category with the associated conditions.

Selbstverständlich gilt auch für bestehende Modelle, egal ob Drohne, Hubschrauber- oder Flugmodell die bereits erwähnte Versicherungs- und Registrierungspflicht.

Effects on existing models

We have listed some examples of drones here to show how they can continue to be operated during the transition period and beyond. As only the take-off weight plays a role, any other existing aircraft can easily be classified.

Das Gewicht der Drohne entscheidet über die Einsatzmöglichkeiten

DJI Mavic Mini, DJI Mavic Mini 2 or Ryze Tech Trello

As these drones have a take-off weight of less than 250 g, only insurance and, due to the built-in camera, registration are required.

Parrot Anafi, DJI Spark or DJI Mavic Air 1

For drones in the weight class from 250 g to < 500 g, registration is required in addition to insurance and, from 01.01.2023, the EU Certificate of Competence A1/A3. After expiry of the transitional regulation on 31.12.2022, operation will only be possible in the open category A3.

DJI Mavic 2 Pro, DJI Mavic Air 2, Yuneec Mantis G, DJI Enterprise Phantom or Yuneec Typhoon H Plus

For drones in the 500 g to < 2 kg weight class, insurance, registration and the EU Certificate of Competence A1/A3 and the EU Remote Pilot Certificate A2 are required. The minimum horizontal distance to persons must be 50 m. After expiry of the transitional regulation on 31.12.2022, operation will only be possible in the open category A3.

DJI Inspire or DJI Matrice M600 Pro

As these copters weigh more than two and less than 25 kg, they can only be operated in the open category A3 or in the special category, depending on where they are used.

Operation of model aircraft in accordance with the new EU regulation

Modellflugzeug schleppt einen Miodellsgelflieger

The new EU regulation also affects remote-controlled model airplanes and remote-controlled model helicopters. This does not change much for model pilots who operate their hobby within an association and on an approved model airfield.

As operation on model airfields is considered to be very safe, the various associations and clubs have the option of applying to the Federal Ministry of Transport for their own operating license.

Model flying can then continue to be operated in accordance with the existing guidelines and regulations. Most models, even if they are not classified, are operated in class C4 and in the open category A3.

As the application for and approval of the operating permit will take some time, flying operations at model airfields can continue without a permit during the transition period until January 1, 2023. The associations also have the option of registering their members collectively with the Federal Aviation Office so that each individual member does not have to do this themselves.

Model pilots who do not belong to an association and do not fly on an approved model airfield must comply with the stricter rules of the EU regulation when practising their hobby. In this case, for example, the maximum flight altitude is limited to 120 m.

Frequently asked questions about the EU drone regulation

Can I continue to fly my unclassified drone after January 1, 2021?

Yes, you can definitely continue to fly the drone. Special transitional regulations apply to ensure this. Depending on the weight of the drone, it depends on which category of the open class you are allowed to fly in. However, it may be necessary for you to obtain a certificate of knowledge or now a certificate of competence from one of the bodies recognized by the LBA.

What do small and large drone licenses mean?

The proof of knowledge according to §21e of the Air Traffic Regulations is also referred to as a small drone license or model flying license. The proof of knowledge according to §21d of the Air Traffic Regulations is also referred to as a large drone license.

What happens to my old national drone license?

According to EU drone legislation, both the drone license and the certificate of proficiency remain valid for one year. After that, the drone license and the certificate of proficiency will be replaced by the EU Certificate of Competence A1/A3 or the EU Remote Pilot Certificate A2. The certificates of competence can usually be obtained from the offices recognized by the Federal Aviation Office following an online course.

What rules apply to hang gliding?

When slope flying with model gliders, a maximum distance of 120 m from the nearest point on the earth's surface must always be maintained. If the model glider including payload is lighter than 10 kg (Maximum Take-Off Mass = MTOM), it can also be flown at a greater distance from the ground. Provided that the height above the remote pilot of 120 m is not exceeded at any time.

What is meant by privately manufactured UAS?

The manufacturer only has to classify an unmanned aircraft if it is a complete system with all the necessary components, such as model, drive and remote control. Even if the system is supplied as a kit and still has to be assembled by the user. If the operator only purchases the model and then retrofits existing remote control or drive components, the model is considered to be privately manufactured. If the ready-to-fly model including battery weighs less than 250 g, it can be operated as a class C0 model in subcategory A1. If the model is lighter than 25 kg, it can be operated as a class C4 model in sub-category A3.