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.

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.

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.

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.

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:

Recording

General

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 6.1.1.31 & 6.1.1.42 ), aeronautical fixed service (ground-ground communications) (Chapters 6.2.2.3.33 , 6.2.2.3.74 & 6.2.2.3.85 ), surface movement control service (Chapters 6.3.1.26 and 6.3.1.37 ) and aeronautical radio navigation service (Chapter 6.4.18 ). Furthermore, ‘Note 1.’ to ICAO Doc 4444 [14] Chapter 7.1.1.2.1 (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, 7.1.1.2.1) required to be recorded and retained to support an effective accident and incident investigation.

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.

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.

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.

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.

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)

Licensing

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.

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.

Current IFATCA policy ADME 2.14 is:

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 – https://ifatca.wiki/kb/wp-2014-92/) is still valid for most of the statements. For the ease of the reader the pertinent paragraphs are listed below:

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.

Regulatory

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).

Action:

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.

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.