Report of the Remote Tower Standing Committee (ROSC)

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Report of the Remote Tower Standing Committee (ROSC)

62ND ANNUAL CONFERENCE, Montego Bay, Jamaica, 8-12 May 2023

WP No. 97

Report of the Remote Tower Standing Committee (ROSC)

Presented by ROSC



The ROSC has had 14 meetings and produced several documents on topics related to remote or digital tower operations. Several proposals for further work are proposed for TOC and possibly PLC job cards.


1.1.  The ROSC (Remote Operations Standing Committee) was established during the Conference of Toronto 2017 under the name Remotely Operated Tower Working Group as a specialized team tasked with the drafting of a position paper on Remote Towers Operations. The group had more than 40 people from all regions and was coordinated through email and Basecamp.

For one year the group developed its task and presented the position paper to committee B+C during the Conference of Accra 2018. The directors decided to change the status of the group to a standing committee.

It was decided to give a boost to the activities of the ROSC in 2022 and since then a group of volunteers have gathered. The coordination of the group is assumed by SESAR/EASA coordinator. 14 online meetings of the ROSC took place and have produced 3 annexes and an interactive map for all the Remote Digital and Tower operations known to IFATCA.

1.2.  The ROSC is composed of Katariina Syväys (Finland), Antonio Anzellotti (Italy) Thomas Kolbeisen (Norway), Thomas Harrison (UK), Adam Rhodes (USA), Péter Szalóky (Hungary), Jaymi Steinberg (TOC), Benjamin van der Sanden (TOC), Ignacio Baca (EVP Tech) and Marc Baumgartner (SESAR / EASA coordinator).

1.3.  The work of the ROSC has the objective to provide more insight in the challenging topic of Remote/Digital Tower, by analyzing some of the identified topics such as Frame Rate, Licensing of ATCOs and recording of new data sources. In parallel, it also provides an exchange platform to coordinate ongoing work at ICAO, EASA, Eurocae and SESAR. If possible, in the coming year, Guidance Material will result as a final product of the work started.

1.4.  This guidance material together with IFATCA policy will assist our representatives and Member Associations in the different fora by providing technical expertise where needed.

1.5.  Coordination with TOC took place during the work with the participation of both the Chair, Jaymi Steinberg and Benjamin van der Sanden, NL.

1.6.  Regulatory material is constantly evolving. ICAO DATS, EASA, Eurocae, FAA and SESAR are continuously updating their respective regulations, recommendations and guidance. E.g. EASA has published ED Decision 2023/005/R Guidance material on remote aerodrome traffic services – Issue 3 on the 31.3.2023. There is a need for the ROSC to keep abreast with the latest publications and evolution of the regulatory material.


2.1. Changes in the Air Traffic Management (ATM) domain are of a continuous nature and challenges of research, development and transition to introduce these changes are daily life for Air Navigation Service Providers (ANSPs) and their staff; air traffic controllers, technicians, engineers, managers, and decision makers. Automation is nothing new in the ATM system. The so-called ‘new technologies’ leading digitalization, including Artificial Intelligence (AI) and Machine learning (ML) are finding their ways into the ATM working environment. Whereas a lot of expectation is linked to technology hype, the introduction of new technology will have to follow the path of introducing new technological components into a running ATM system.

A Digital Tower environment offers possibilities to use technologies in a novel way and comes with new challenges for the Air Traffic Controllers working in such an environment. Licensing, in particular where current EASA licensing regulation prevails, opens a new challenge for Air Traffic Control.

2.1.1.  The provision of aerodrome air traffic services (ATS) from remote locations is receiving more and more attention. Remote operational services have been provided at airports open for commercial aircraft operations since April 2015 and several new services are being deployed. The concept of ‘remote provision of aerodrome air traffic services’ (commonly known as remote tower operations) enables the provision of aerodrome ATS from locations where direct visual observation is not available. Instead, provision of aerodrome ATS is based on a view of the aerodrome and its vicinity through means of technology.

2.1.2.  A remote (or digital) tower module is equipped similarly to a conventional air traffic control tower. Systems and equipment at the airport are connected to the remote digital tower module, i.e. a ‘tower’ where aerodrome ATS are based on digital information only. Cameras located at the airport provide a visual presentation of the airport and its vicinity that is displayed on screens located in the digital tower module, thus providing air traffic control officers (ATCOs) and aerodrome flight information service officers (AFISOs) with a watch over their area of responsibility, either fully or partially. Depending on the equipment used, aerodrome ATS could be provided in the same way as from a conventional tower with no particular change in the service provided. However, the technology is flexible in a way that it can be configured to provide a subset of air traffic control tower (ATCT) services for potential cost savings. For example, a remote tower can be used next to a conventional tower when one of the runways is located at a great distance from the conventional tower. ATCOs/AFISOs will use working methods similar to those which they are used to. Some adjustments will have to be made due to potential distortion or compressed displayed images that affect the perception of distances for operations, when it comes to separating departures and arrivals, for instance. This can be addressed by considering cognitive processes and human factors in the development of remote towers.

Figure 1 – Illustration of a Single Digital Tower – credit think research

2.1.3. Several tower modules may be located in a remote tower centre (RTC), a centralised facility where aerodrome ATS are provided to one or more aerodromes. This can be compared to an area control centre (ACC) where ATC is provided to many sectors or approach functions.

Figure 2 – Illustration Multiple Digital Tower – Credit Think Research

2.1.4. Digital Tower – ICAO will regroup all the remote or digital tower services and the future heading of Digital Air Traffic Services for Aerodromes (DATS) from a semantical point of view. IFATCA believes that modernization of conventional towers with a higher degree of digitization leading to a digitalized working environment in a “classical” tower cabin environment will become more prominent and might be a significant game changer (e.g. Low Visibility Procedure potentially evolving to Electronical Visibility Procedures) (This term does not exist and has been coined by the authors of this paper for illustration purposes only). Industry is already providing multi-layered solutions for a classical tower environment.

Under the chapter “how do I get started”, CANSO provides in their guidance material an update on all the rule-making and standardization processes which are ongoing in the field of DATS.

2.2.  The interactive global map

Remotely Operated Airports – Google My Maps was created by Katariina from Finland in order to provide a easy overview at the global level of the various initiatives. This map is ready to be published to a wider audience. In order to improve the intelligence on the ongoing initiative, the ROSC would like to invite Directors at conference to indicate if they are aware of certain plans to set up and/or implement remote/digital towers.

2.3.  Following the possible feedback received from the Member Association IFATCA will then advertise and publish this global interactive map.

2.4.  Guidance Material

An overall objective of the current work of ROSC is to be able to establish guidance material for the Member Associations. In order to achieve this, 3 working papers have been drafted and are integral part of this action paper to conference. They are listed as annexes. Further work is currently ongoing on multiple remote towers.

2.5.  Job Cards

In the recommendation of this Action Paper job cards for TOC and PLC are suggested.

2.6.  Topics addressed in the annexes

Three topics have been addressed by the work of the ROSC.

  • License
  • Recording
  • Frame Rate

The ROSC proposes a fourth annex on the topic of Multiple Remote Tower. The tenure is different than the three other annexes.


3.1. Digital technology makes it possible to provide tower ATC from a remote location. This poses new challenges regarding different elements of a tower ATC system.

3.2.  IFATCA has created a ROSC to address some of the new challenges related to remote/digital towers.

3.3.  The representatives of IFATCA in the various bodies promote the views and the policies of IFATCA. These representatives have to adapt to the new developments in this domain and need support in form of policies and or guidance material. The ROSC is trying to provide input to the current policies, propose job cards to TOC and PLC and provides guidance material.

3.4.  A further feature has been created which is the interactive global map on remote/digital tower operations. Member Associations assistance is required to complete the interactive map with the planned new projects related to remote/digital tower operations.


4.1.  Conference is invited to discuss the recommended job cards for TOC and PLC as follows:

a)  it is proposed that TOC/PLC investigate the need to create new policy on the data being used to record. The veracity of the data needs to correspond to the working environment of the ATCO and not to the technical possibilities of the data set/source.

b)  it is proposed to TOC/PLC to further study the Data management in ATM

4.2.  For reasons of safety and human factors issues the minimum frame rate in a remote tower operational unit shall be 25 FR for single remote towers.

4.3.  A new possibility of a cloud-based transmission of the data shall be assessed when proposed by industry.

Annex I – Data Recording

Technical Enablers for Digital Air Traffic Services for Aerodromes

EASA in the Easy Access Rules for Guidance Material on Remote Aerodrome Air Traffic Services describes the following Technical Enablers for DA TS:

  • Visual presentation, replacing, or complementing, the OTW view of a conventional tower.
  • Binocular functionality (e.g. a pan-tilt-zoom (PTZ) camera/function, as defined and described in ED-240A), fulfilling/emulating the function of a binocular in a conventional tower.
  • Signaling lamp, remotely controlled.
  • Aerodrome sound reproduction.
  • Communication means to provide aeronautical mobile service, aeronautical fixed service and surface movement control service.
  • Management of navigation aids, aeronautical ground lights and other aerodrome assets.
  • Meteorological information.
  • Other ATS systems/functions, as would typically also be available in a conventional tower, but which are not necessarily affected by the remote provision of ATS.
  • Additional visual ‘hot spot/gap filler’ cameras.
  • The use of infrared or other optical sensors/cameras outside the visible spectrum.
  • Dedicated means to facilitate the detection and identification, as well as enabling automatic following, of aircraft or vehicles in the visual presentation (e.g. by overlaid labels based on data from ATS surveillance systems/sensors e.g. ADS-B, PSR, SSR, A-SMGCS, complemented by flight plan correlation when available, commonly referred to as ‘radar tracking’).
  • Dedicated means to facilitate the detection and following of moving objects in the visual presentation (e.g. by highlighting/framing such objects based on image processing techniques, commonly referred to as ‘visual tracking’).
  • System support to help the ATCO/AFISO detect smaller foreign object debris (FOD), highlighting the existence of such small objects in the visual presentation.
  • Other overlaid information in the visual presentation such as framing and/or designation of runways, taxiways, etc., compass directions, meteorological information, aeronautical information (NOTAM, SNOWTAM, etc.), other operational information (e.g. runway conditions like water, snow or mud presence, coefficient of friction, etc.).
  • Enhanced functionalities of the binocular functionality, e.g. automatic following of moving objects.

EASA cognizant of the evolutionary nature and the technological changes ongoing explains as an introduction to this chapter the following:

The solutions which are available for remote aerodrome ATS are not based on a unique system configuration but on a varied set of technical enablers. The appropriate configuration of technical enablers should be carefully assessed and selected according to the operational needs of each implementation and supported and identified by the safety, security, and human factors assessments. Below is a (non-exhaustive) list of possible technical enablers.
Many of the below listed enablers are also available for conventional towers; however, in the remote tower context they will be affected to various degrees due to the need for data transmission links.

Further details on the enablers are addressed in the Chapter 5 of the Easy Access publication (mentioned).

IFATCA representatives have introduced a further potential enabler as a compliment of the EASA list:

  • Surveillance (MLAT, ASR, ADS-B, A-SMGCS)
  • Electronic strip system
  • AI-solutions machine learning
  • Electronic planning and workload forecast tools
  • ATIS and an automated weather observation system AWOS
  • VoIP radio systems
  • Silent coordination between ATC units



EASA Easy Access specifies in chapter 5.6. Voice and Data Recording that the philosophy of the ICAO provisions is to record and retain all data used to support the provision of ATS. For the particular case of remote aerodrome ATS, the recording and retention of data should therefore be extended to include constituents specific to remote aerodrome ATS, including the visual presentation, the binocular functionality and other technical support systems such as the aerodrome sound reproduction.

ICAO Annex 11 Chapter 6 specifies recording requirements for aeronautical mobile service (air ground communications) (Chapters & ), aeronautical fixed service (ground-ground communications) (Chapters , & ), surface movement control service (Chapters and ) and aeronautical radio navigation service (Chapter 6.4.18 ). Furthermore, ‘Note 1.’ to ICAO Doc 4444 [14] Chapter (introduced by ‘Amendment No. 8’ applicable as of 8 November 2018) clarifies that ‘For the purposes of automatic recording of visual surveillance system data, Annex 11, 6.4.1 applies’.

EASA further explains that:

As a minimum, the image presented to the ATCO/AFISO (i.e. the processed data presented to and used by the ATCO/AFISO as support in their decision-making, including both the view of the aerodrome and its vicinity, as well as any overlaid data/information/decision support; sometimes referred to as ‘screen recording’), is (in accordance with ICAO Annex 11, 6.4.1 and with Note 1 to ICAO Doc 4444, required to be recorded and retained to support an effective accident and incident investigation.

In addition, the sensor data (i.e. the data recorded by the sensors) may also be recorded to further support accident and incident investigation.

It should be noted that integrity issues may result from the recording and retention of optical/video/sound data from public spaces (which could be the case for an aerodrome, depending on the national legislation). Such integrity and privacy issues are different from state to state depending on national integrity and surveillance legislation and would need to be taken into account.

Aviation Safety has hugely improved over the last century thanks as well to rigorous accident and incident investigation. Reporting of incidents is a crucial backbone of this safety track record. ICAO Annex 13 and 19, as well as the EU IR 996/2010 and in particular 376/2014 regulate the content and form of reports which are expected to be reported by Aviation professionals. The use of safety data and safety information are regulated by these recommendation practices. Recording of data provides one of the pillars of accident and incident investigation. Any new data source in a working environment generates data, which if required can be recorded. That poses some issues which have to be discussed by the Staff employed by an Aviation undertaking like an ANSP or an airline.

Eurocae WG 100 is currently working on establishing standards for data recording and IFATCA is involved in this discussion. Several new data sources pose different challenges and Eurocae in their draft working document highlights but a few:

  • Video recording – is new and offers possibilities for accident and incident investigation, training (basic and refresher), technical (maintenance planned/unplanned, prototyping, shadow mode etc.)
  • Data volume
  • Data source
  • Data storage
  • Privacy and confidentiality


Audio and visual recordings and AWR are confidential and shall not be released to the public.

Audio and visual recordings and AWR shall not be used to provide direct evidence, such as in disciplinary cases, or to determine controller competence.

Except for AWR, recorded data shall be used only in the following cases:

a) when investigating ATC related accidents and incidents;

b) for search and rescue purposes;

c) for training and review purposes provided all ATCOs affected agree. d) for the purposes of adjusting and repairing ATC equipment.

Access to recorded data shall be limited to authorised personnel. Authorised personnel shall be mutually agreed by the controllers’ representative and the appropriate authority. Recorded data used shall be identical to that presented at or originating from the relevant controller’s position.

IFATCA is opposed to the use of visual AWR on the basis of invasion of privacy.

AWR shall only be used to aid in incident and accident investigations to improve aviation safety.

Prior to the installation of AWR, legislation shall be in place which prohibits the use of any recorded information against a controller in any criminal or civil litigation. The legislation should provide for substantial penalties for any breach.

The AWR system, including user management and access to the recordings, should be managed by an independent authority within the ANSP, chosen jointly by management and Member Association(s).

Before being published in an incident or accident report, non-relevant information shall be removed from AWR transcripts.

Data Source

In Digital Tower environment different (new) data sources become available. For clarity purposes this paper proposes a few basic graphic explanations to better outline the challenges IFATCA has identified.

At the aerodrome

At the airport different data sources can be recorded. It is important to understand what kind of data can be recorded. Video and Audio as well as Others such as Weather information. This data might be recorded for various purposes, including, maintenance, accident/incident investigation and or for educational purposes.

Figure 1 – Different data sources at the airport can be recorded – source author

It is important to note that the data at the source (antenna, camera and or audio) might not be the same as the data which the ATCO in the remote station will have access to. This for various reasons:

  • Raw data from the source might not be transmittable at the same data rate to the remote station.
  • The data might be too heavy and not useable to be displayed.
  • The focus of the recording is a different one that the ATCO needs.

If the cameras are adjustable for focus, object search, audio source etc. The adjustment movements of the data source might also be recorded. This will permit a further assessment of the behaviour as well of the ATCO and needs to be communicated to the operator to make him aware what data can be gathered at the source.

At transmission

The transmission of the data in a digital tower is of crucial importance and according to the experience of our members poses a challenge in particular of economic nature. The fiber optic chosen to transmit the data can be a expensive and some ANSP are reluctant to invest in a high performance fiber optic transmission conduit. Data which can be recorded is the transmission rate which could be used for technical and accident/incident investigation. New cloud based technology offers the possible to storage the data or transmit the data into a cloud. Recording these cloud based data offers different possibilities of use of the data.

For the logic of this paper the follow graph shows schematically the transmission conduit from the Antenna to the remote unit.

The data will land either on a physical or a virtual (cloud) server and will have to be prepared for the operations room. That is achieved by compression, fusion, extraction (decoding), and formatting of the data. This process can be recorded mainly for technical purposes.

The data being used in the remote operational control unit will not be the data recorded at the source and therefore a separate recording of the data used at the working place has to be recorded.

Data in the operational room can include the following:

  • Air/Aerial display (Screen or multitude of screens)
  • Beamer
  • Controller working position
  • Radio and Telephone communications
  • Auxiliary systems used to perform ATC (e.g. weather radar, departure sequences, A- SMGCS) etc.
  • Working place measures like moisture, temperature, noise etc.
  • Ambiance voice recording
  • Ambiance video recording

Each of this system will have a different set of data source and can be recorded.

Challenges with Recording

Eurocae working group 100 on remote tower has identified 4 categories of challenges:

  • Data volume.
    Real-time video taken from multiple points in the RTOS processing chain will give a huge volume of data. Measures such as compression, lowering the recording rate and selective recording may be necessary to reduce the volume of data recorded.
  • Selection of data stream(s) and content.
    Video data taken from different points in the RTOS processing chain will have different characteristics as it may be altered, either deliberately by processing such as compression and augmentation or accidentally by degradation due to failures or network packet loss. It may also be possible to obtain non-video data such as operator inputs to human- machine interfaces.
  • Data management: storage and retrieval.
    Recorded data will need to be stored and managed to assure its quality, retention for the required time period, confidentiality, and also to allow timely access to desired data.
  • Privacy and confidentiality.
    It is essential that operators understand the scope and purposes of data recording and consent to its use. Operators and/or their representatives should be fully informed and consulted about the implementation and use of an RTOS recording function from the earliest stage possible.

IFATCA’s View on these Challenges

Data volume: There is a risk that to reduce the volume of data that solution to compress the recorded data and or the displayed will lead to different recording data than what the ATCO has used to do her job.

Selection of data stream(s) and content: Same risk that the data which is recorded is a different one then the data used by the ATCO.

Therefore it is proposed that TOC/PLC investigate the need to create new policy on the data being used to record. The veracity of the data needs to correspond to the working environment of the ATCO and not to the technical possibilities of the data set/source.

Data management: Storage and retrieval needs to be regulated considering, national legislation, physical or cloud location. From the Cockpit voice recording experience, a lot of technical and regulatory possibilities and requirement could find their way into the remote and digital future ATM environment. This needs a proper study in particular issues like:

Data source not in the same country as data storage. Different national legislation. Access to the data from a remote place which might not be co-located with the ATM Unit. Who has how and when access. Some of the technical monitoring function use the same data as the accident/incident investigation.

Therefore it is proposed to TOC/PLC to further study the Data management in ATM.

Privacy and confidentiality:

This might the most challenging part of the Data Management. Example show, that after accident investigation recommendation the ICAO standard on Ambiance voice recording need in some countries special law to be created, as the violation of the private sphere is so high by such recording devices that it can not be implemented before the law is adapted.

This challenge is particular important if the data storage and the access of the data is not taking place in the same country as the Digital Tower activity. Particular attention needs to be paid to the access to data which are protected by privacy laws. In many countries this has been solved by issuing strict working instructions for technicians and maintenance staff (e.g. Non disclosure Agreement).

Proposed Guidance for the IFATCA members:

If an ANSP is preparing for a digital tower environment the Association shall seek discussion with management and industry solution providers to understand what and where data is being recorded.

Member Association shall verify if the proposed data recording is using the data which is available to the ATCO working place and ATCO working environment. Any fusion or composed data shall not be acceptable other then for technical purposes.

Care shall be taken before accepting any form of data recording, with regard to possible conflict with the privacy laws of the country of the workplace, the country of recording.

Special agreements (NDA) shall be submitted to the technical maintenance staff in charge of extracting or manipulating the data in question.


With the advent of more digital tower environment Members of IFATCA are faced with new challenges. One of them being the use of recorded data in a digital tower environment. The technical possibilities are allowing more use of larger data at different sources.

The Remote Tower committee of IFATCA has discussed this topic and comes to the conclusion that the current IFATCA policy shall be adapted to include in particular elements like data volume, data source and the specific legal challenges the new recording possibilities offer.

Annex II – Frame Rate

Frame rate per second – 1, 5, 25, 50 what is right?

IFATCA is involved in the work on the future digital working environment for Air Traffic Control for Digital Towers. One of the ongoing works is the Digital Tower is the technical specifications for the Frame rate per second for Video at the aerodrome.

Currently the discussion tends to go for a low-cost solution which creates challenges from scientific and operational perspective. Eurocae WG 100 is setting a minimum Frame Rate for the Videopanorama or Video Frame Rate (FR). Its co-chair (Jacobi & Hagl, 2018) argue in a conference paper that:

“Bandwidth, often limited and costly, plays a crucial role in cost- efficient Remote Tower system.”

Therefore, a passive shadow mode exercise was conducted by the DLR research institute with 7 ATCOs in order to assess how far the FR can be reduced without without compromising operational performance and human factor issues. Study results have shown that by reducing the FR, neither the visual detection performance nor physiological state is impaired. Only the perceived video quality and the perceived system operability dropped by reducing FR down to 2 fps.

Other studies tend to show different results. In the same publication as the above cited article Fürstenau and Ellis (2018) come to a different solution.

In order to determine the required visual frame rate (FR) for minimizing prediction errors with out-the-window video displays at remote/virtual airport towers, thirteen active air traffic controllers viewed high dynamic fidelity simulations of landing aircraft and decided whether aircraft would stop as if to be able to make a turnoff or whether a runway excursion would be expected. The viewing conditions and simulation dynamics replicated visual rates and environments of transport aircraft landing at small commercial airports. The required frame rate was estimated using Bayes inference on prediction errors by linear FR-extrapolation of event probabilities conditional on predictions (stop, no-stop). Furthermore estimates were obtained from exponential model fits to the parametric and non-parametric perceptual discriminabilities d′ and A (average area under ROC-curves) as dependent on FR. Decision errors are biased towards preference of overshoot and appear due to illusionary increase in speed at low frames rates. Both Bayes and A—extrapolations yield a framerate requirement of 35 < FRmin < 40 Hz. When comparing with published results (Claypool and Claypool Multimedia Systems 13:3–17, 2007) on shooter game scores the model based d′(FR)- extrapolation exhibits the best agreement and indicates even higher FRmin > 40 Hz for minimizing decision errors. Definitive recommendations require further experiments with FR > 30 Hz.

For the general public (Chen and Thorpp 2007) come to the conclusion that 15 Hz and above are generally more widely preferred.

Effects of different frame rates (FRs) on human performance and reviewed more than 50 studies and summarized them in the areas of psychomotor performance, perceptual performance, behavioral effects, and subjective perception. Overall, there seems to be strong support for a threshold of around 15 Hz for many tasks, including those that are psychomotor and perceptual in nature. Less impressive yet acceptable performance may be accomplished at around 10 Hz for many tasks. Subjective reactions to the quality and watchability of videos seem to support rates of 5 Hz, although videos presented at 15 Hz and above are generally more widely preferred. These generalizations regarding superior and acceptable FRs may also be subject to the effects of several moderating factors such as display characteristics, nature of the tasks, viewing condition, additional cues, and user experience.

Further studies in the field of Digital Tower environment recommend at least:

“The principal result of the study suggests that relatively high frame rates will be required for imagery in virtual or remote towers if controllers working in them are expected to perform the kinds of subtle visual motion discrimination currently made in physical towers.” (Fürstenau et al., PROCEEDINGS of the HUMAN FACTORS and ERGONOMICS SOCIETY 55th ANNUAL MEETING – 2011)


“Decision errors are biased towards preference of overshoot and appear due to illusionary increase in speed at low frame rates. “(Fürstenau and Ellis, 2016)


“Our preliminary results on the minimum frame rate for minimizing prediction errors (FRmin > 30 Hz) show that a definitive recommendation of a minimum video frame rate and a confirmation of our initial hypothesis of visual short-term memory effects resulting in the proposed asymptotic characteristic require a further experiment with FR > 30 Hz.” (Fürstenau and Ellis 2016)

The impact in a Multiple Remote Tower environment of workload, alertness, fatigue was extensively study by Wen-Chi Li et al., (2020 , 2019, 2018). Current discussion on the needed minimum standards are influenced by the industrial possibilities with regard to bandwidth for the transmission of the data. The bandwidth depends on the transmission of data. It might be costly, in competition with other users and therefore there seems to be a trend to advocate a lower Frame Rate than what is currently being discussed at the Standardisation body.

This in order to avoid any safety and human factors issues once in place. In Europe EASA and Eurocae have the responsibility to set this standard. In other countries like the US it is the regulator who fixes the minimum FR.

From an IFATCA perspective it should be at the minimum 25 FR for a single remote tower. This in order not to jeopardize the safety of the travelling passenger.

The RTC group is proposing to TOC PLC to adapt the current remote tower policy to add a definition as follows:

For reasons of safety and human factors issues the minimum frame rate in a remote tower operational unit shall be 25 FR for single remote towers.

A new possibility of a cloud-based transmission of the data will have to be assessed when proposed by industry.


With the advent of more digital tower environment Members of IFATCA are faced with new challenges. One of them being the use of recorded data in a digital tower environment. The technical possibilities are allowing more use of larger data at different sources.

The Remote Tower committee of IFATCA has discussed this topic and comes to the conclusion that the current IFATCA policy shall be adapted to include a definition of the Framerate.

Further the IFATCA RTC shall request EVP Tech together with EVP Europe to address this request in a letter to Eurocae, EASA with copy to ICAO and CANSO.

Annex III – Licensing/Endorsement/Ratings

Air Traffic Controller License

WikIFATCA stipulates under Licensing and Training the following:

ICAO Annex 1 details the standards and recommended practices (SARPs) for personnel licensing. Although not defined in the Annex, a licence per definition is a permit from an authority to own or use something, do a particular thing, or carry on a trade. Licensing is a system of standards, processes and procedures to ensure that personnel undertaking safety related tasks in civil aviation (pilots, air traffic controllers, aircraft maintenance engineers, etc.) are competent to perform their tasks to the prescribed standards.

Annex 1 also sets out the applicable ATCO standards for the rating, validation, training, aviation English and procedures for acquiring a licence, keeping the licence valid, renewal of the licence and even provisions for withdrawal of ATC licence under certain conditions. Where all these conditions are met, the ATCO is licensed to perform an air traffic control service. Where they are not, the ATCO cannot perform an air traffic control service.

Provisions related to ATCO training are found in both Annex 1, Chapter 4 and PANS-TRG, Part IV. In 2016, ICAO introduced the Competency-Based Training and Assessment (CBTA) approach, further detailed in Doc 10056 – Manual on Air Traffic Controller Competency- based Training and Assessment

(working paper 97 2018)


The approach to the job, the environment and the modes the tasks of the operators are accomplished in RTOs are different from today’s work and the environment of the conventional towers. Tasks and responsibilities will differ depending on technical equipment and supporting tools than in conventional towers. Staff will be faced with significantly different settings to perform and achieve service provision.

IFATCA policy is:

Provisions, training programmes, separation standards and a specific Remote Tower endorsement are required for operating at Remote and Virtual Towers.
(IFATCA Technical and Professional Manual (2017), ADME 2.15 Page 3 2 2 17)


The conclusion of the WP 158 of 2017 stipulates:

ATCOs and their associations are asking for an IFATCA guideline or better policy about ROT licensing where no regulations at all are in place yet. Experience is difficult to obtain due to the fact that there are only very few remote towers already operational. The question if a special rating for ATCOs operating ROT is needed is not yet answered because of no available reported experience. IFATCA will continue to monitor the situation and asking all member associations to report any experience.

The European Expert Group of the Human Dimension comes to the following request in their paper on the human dimension in remote tower operations (2017)

Licencing and endorsement

The need for a specific remote tower unit or rating endorsement in CIR 340/2015 (ATCO Licence regulation) should be studied. The EGHD recommends that two scenarios are analysed:

Specific remote tower rating endorsement: The use of RTO may require a specific rating endorsement; this would be an endorsement attached to an Aerodrome Control Visual (ADV) or Aerodrome Control Instrument (ADI) rating and not linked to unit endorsement. This view considers that remote towers are a technical means to providing a service. The analysis should consider the opposite case and experience regarding the change: what would be required for an ATCO working in a remote tower centre and who move to a conventional tower with no previous experience?

Remote tower unit endorsement: If a service can be provided both from a remote tower and a conventional tower (switching from one to the other depending on time or any other criteria) then the remote tower and the conventional tower would be two different units requiring two different unit endorsements. ‘RTO’ can be mentioned in the unit endorsement name to differentiate it from the conventional tower unit endorsement, but it should not refer to a specific kind of unit endorsement (in case of only and permanent remote TWR there is no need to specify ‘RTO’ in the unit endorsement). The possibility of temporary unit endorsement should be evaluated.

In any case, training plans and competence assurance plan should meet new EU/EASA regulations and be approved by the relevant NSA. In addition, EGHD recommends that lessons learned for licensing and endorsement for multiple aerodromes should be studied.

Licencing arrangements for more than one aerodrome: Licensing arrangements for more than one aerodrome needs to be addressed. EGHD recommend that the current approach of one unit endorsement for each aerodrome is maintained.

Recommendation 4

Assess CIR 2015/340 to ensure that operators have appropriate competencies and training. Licencing and endorsement should be adapted to remote tower context based as far as possible on current working practices.

To date no update on the request of EGHD to study this issues is known to IFATCA.

Member association report that they do start to see creative low-cost solution created by the ANSP faced with their ambitions and business plans to make many aerodromes remotely controlled.

There is a need for the RTC group to discuss and push this issue further with a proposal to the annual conference 2024 for a policy.

Annex IV – Multiple Remote Towers


Current IFATCA policy ADME 2.14 is:

ATCOs shall not be required to provide a Remote and Virtual tower service for more than one aerodrome simultaneously.


The ROSC has reflected on the need to address this policy and has come to the conclusion that Multiple Remote Tower albeit the current policy of IFATCA will be put in place in different countries. The WP 2014/92 (Study Remote Towers Concept, IFATCA TOC, Gran Canaria 2014 – is still valid for most of the statements. For the ease of the reader the pertinent paragraphs are listed below:

2.10.1 ANSPs and ATM suppliers have widely promoted the benefits of consolidating tower ATCO staffing into central locations. It is inevitable that with RVT technology, ANSPs will seek to establish centres (RTC) where numerous aerodromes are controlled from a single facility. This will likely result in tower controllers being expected to hold endorsements for multiple aerodromes.

2.10.2 There are existing examples where ATCOs concurrently hold endorsements for more than one aerodrome, however it is unlikely that more than one of these would be exercised in a single shift, as the aerodromes would be in different locations.

2.10.3 In situations where controllers are expected to maintain and exercise multiple endorsements, training (including refresher training), rest breaks, HMI design and other relevant factors must be taken into account to ensure controller competency. It may be necessary to align procedures at airports where controllers are expected to hold multiple endorsements, such as renaming taxiways and visual reporting points and aligning alarm plans and Letters of Agreements between the ANSP and the aerodrome operator and approach control.

2.10.4 Stated plans by some ANSPs for ATCOs to operate more than one tower simultaneously are of significant concern. The potential for sudden unexpected peaks in workload and loss of situational awareness could lead to a significant reduction in ability to provide safe ATS, including during expected periods of low traffic.

2.10.5 The concept of operating multiple towers simultaneously differs greatly from the enroute or approach environment, where there are numerous examples of controllers performing different control functions (eg. enroute combined with approach, or operating numerous enroute sectors). Generally when enroute and approach functions are combined, it will be a contiguous and coherent volume of airspace, allowing the controller to develop a single mental model of the situation. Operating multiple towers would result in a fragmented situational awareness, and there is potential for significant differences in factors such as weather between the aerodromes.

2.10.6 Instead of operating several aerodrome simultaneously, it might be possible to reduce costs by co-locating an RTC next to a TRACON or ACC and work tower and approach as a common rating and by the same body of controllers, combining TWR and APP functions at times of low traffic.

Confronted with the decision of some states and or ANSP to introduced RTC, IFATCA Member Association should be able to be associated to the debate how and when to introduce RTC. This is an important aspect in order to run such RTC operation in a safe and financially sustainable way.

Therefore Guidance Material shall be elaborated in the future on different elements of the future Multiple Remote Tower operations.

What elements do need to be addressed in future Multiple Remote Tower environment

Workload – ATCO Performance

Kearney et al., (2019) outlined that results demonstrate that augmented visualization provided sufficient technical support for a single ATCO to perform tasks originally designed to be performed by four ATCOs, that however , the demands of the associated multiple tasks induced significant workload. In their research they came to the conclusion that significant differences in ATCO’s mental demand, temporal demand, effort, and frustration between Multiple – Remote Tower Operation and physical tower operations. The innovative technique used may induce human-computer interaction issue that impact ATCOs perceived workload. This creates the need for further research on how to manage ATCO’s workload in a multiple remote tower environment.

(Reference: Kearney P. , Wen-Chin L., Jingyi Z. et al., Human performance assessment of a single air traffic controller conducting multiple remote tower operation, 2019 DOI: 10.1002/hfm20827)

What type of ATC to be provided

One of the most important elements which need to be describe what kind of Air Traffic Service is provided in a RTC. Many initial ideas were to use AFIS and low density airport as launch platforms. This poses two questions. Where in the past AFIS rules prevailed, the new technology might offer the hybrid format of ATC provided in an AFIS environment. Rules of the air and air traffic control can change significantly. Separation standards need therefore to be taken into account.


As ATC is a safety industry different rules need to be used than in other industries. These safety requirements do lead to create a need for a solid regulator coaching of the ANSP when it comes to establishing the future Rules of the Air in a Multiple Remote Tower environment.

Separation standards might have to be developed for these operations, to take into account sequencing, spacing and other aerodrome related standards. They might have to established beyond the ICAO SARPS and thus need a good understand from the regulator.

In WP 174 to the 2018 ICAO 13th Air Navigation Conference outlined in the Executive Summary that:

This paper provides information regarding remotely provided aerodrome air traffic services (ATS), commonly known as remote or digital air traffic control towers, and requests ICAO to take steps to develop globally harmonised guidelines on the implementation of these services by States or air navigation services providers (ANSPs).


The Conference is invited to:

a) note the information on the use and development of remote towers presented in this paper;

b) request ICAO to take advantage of provisions developed in Europe and elsewhere that support remotely provided aerodrome ATS;

c) request ICAO to encourage other States and standard development organisations to collaborate on global provisions for digital ATS;

d) request ICAO to initiate the development of a common set of guidance material to ensure the availability of high quality and secured digital ATS information in a timely manner; and e) recommend that ICAO coordinates the development of guidance material with relevant industry stakeholders.

The trend seems to be to use simultaneously different separation technique at different airport. The ROSC is of the opinion that this needs to further addressed, as it would make more sense that an ATCO being responsible for different airport simultaneously should not be burdened with an undue workload and should be able to work different airports as one ATM unit with one separation standard. Meaning that simultaneous operation would never be allowed, but sequencing operations might be allowed under certain very strictly defined parameters.

Human Factors

Research in the human factors, and cognitive limitations is not mature to allow a clear view on the human factors issues raising from Multiple remote towers. Therefore careful job analysis should be carried out. This is described in some of the work of the Joint Cognitvie Human Machine System on Generic Principles

Generic Principles

Reliable and effective operator-centered technology systems should be designed following general best practices, together with practices that address considerations unique to AI/ML and autonomous systems. Our recommendations are outlined below in the form of nine principles.

The first six apply to any technology system while the last three apply to AI systems:

1) Focus on designing and delivering operator-centered technology. The way actual users experience the technology system is essential to assessing the true impact of its predictions, recommendations, and decisions in the operational context. Technology design features with appropriate levels of disclosures must be built in. Clarity and control are crucial to an effective operator experience.

2) The trade-off between augmentation and assistance must be carefully balanced. A single answer may be appropriate where there is a high probability that the answer satisfies a diversity of opearators and use cases. In other cases, it may be optimal for the proposed system to suggest a few options to the operator. Technically, it is much more difficult to achieve good precision at one answer versus precision at a few answers.

3) Aim for a diverse set of operators and use-case scenarios. This will build a rich variety of user perspectives into the project and incorporate feedback before (early) and throughout the technology project development.

4) Develop and utilize several technology specific and operational metrics. The use of several metrics rather than one will assist in understanding tradeoffs between different kinds of errors and 􏰋perators’ e􏰌periences􏰄 Technolo􏰂􏰃 specific metrics must include feed􏰁ac􏰆 from user surveys, and indicators that track overall system performance both short- and long-term. It is important to ensure that the metrics are appropriate for the operational context and goals of the unit or the ANSP.

5) Design the technology with the capability to monitor and update the system after deployment. Continued monitoring will ensure any model used takes real-world performance and user feedback into account. Issues with dysfunctional interactions will occur because any model of the world is imperfect almost by definition. Building time into the technology product roadmap to allow addressing emerging and anticipated issues is vital. Trade-off between short- and long-term solutions to issues must be carefully balanced. Before updating an already deployed model, careful analysis of how the new and deployed models differ, and how the update will affect the overall system safety and user experience.

6) Test the systems in isolation and in cooperation with the other affected systems. Making sure the system is working as intended and can be trusted is essential at the OPS rooms and training facilities. Rigorous unit tests to evaluate each component of the system in isolation and integration tests to understand how individual system components interact with other parts of the overall system is essential. Conducting iterative user testing to incorporate a diverse set of users’ needs in the development cycles is also crucial.


Syvays K., in Remote & Digital Towers, ATC-NETWORK.COM Special Bulletin Series 2020/21, access on 23/02/04.

ICAO annex 11, Edition 2015, ICAO, Montreal.

Eurocae WG 100 is working on the ED 240 Standard. The work is ongoing and the table below can not be reproduce as the document is not released.

Jakobi, Jorn and Hagl, Maria (2022) Which minimum Video Frame Rate is needed in a Remote Tower Optical System. In: Virtual and Remote Tower (2nd edition) – Research, Design, Development, Validation and Implementation Research Topics in Aerospace. Springer Publishers. pp. 405-426. doi: 10.1007/978-3-030-93650-1_17. ISBN 978-3-030-93649-5. ISSN 2194-8240.

Last Update: September 26, 2023  

September 17, 2023   96   Jean-Francois Lepage    2023    

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