Summary

Remote and Virtual Towers are being implemented in greater numbers worldwide. This paper reviews IFATCA policy in order to keep it updated to the current developments. Work will continue on this topic for some time.

Introduction

1.1 This paper is intended to review IFATCA policy ADME 2.14 regarding Remote and Virtual Tower. This policy was last updated at conference in 2017 and development of Remote and Virtual Tower Systems, as well as implementation of said systems has continued globally.

1.2 Remote and Virtual Tower Systems have been implemented in different forms and configurations. There are now multiple locations that have consolidated providing ATS for multiple aerodromes. Other configurations exist where the digital tower is located near, or even on, the original aerodrome. Providing a supplement, or in some cases, completely replacing the conventional tower. There have been signals from several sources however, that the consolidating approach is the more cost effective one. TOC therefore expects an industry push for more of these centers.

Discussion

Current Events and Concerns

2.1 The multitude of different configurations and service levels makes the subject matter complex, as it becomes impractical to formulate a “one-size-fits-all” policy or standpoint which applies across the board. A more in-depth analysis of these issues can be found in paragraph 2.8 and onwards, in the section “Policy Analysis”.

2.2 Alongside this policy review, IFATCA’s Remote Tower Task Force is making continuous efforts to monitor the situation and developments and is in the process of updating guidance material on the IFATCA website. In addition to this, an interactive map will be created for those interested. The map allows people to learn about the locations and service level of Remote and Virtual Towers. Lastly, the task force is creating a reference document with guidelines, requirements, and best practices to help with the implementation of Remote and Virtual Tower Systems. Educating our members on the concepts, benefits and hazards of these systems is
essential in the near future, as IFATCA expects systems like these to be rolled out in more and more locations.

2.3 ICAO’s ATM Ops Panel (ATMOPSP) has recommended changes to various Annexes to bring them in line with the requirements for aerodromes where Remote systems are active (Digital Air Traffic Services for Aerodromes (DATS) proposals for amendments: Draft DATS PfAs, ICAO ATMOPSP November 2022).

2.4 An amendment is proposed as well to redefine the requirement to maintain a “continuous watch” as a “continuous situational awareness” of all traffic in the vicinity of an aerodrome.

2.5 Furthermore, a new term will be introduced to refer to Remote and Virtual Towers. “Digital Air Traffic Services for Aerodromes” or DATS. IFATCA policy will be amended to reflect this change and to maintain alignment with ICAO documentation. The author notes that the acronym omits the final A. It must remain clear that the term specifically refers to services at aerodromes and does not cover other forms of Digital Air Traffic Services (i.e., CPDLC, D-ATIS, etc.)

2.6 It is expected that the modifications to the Annexes, as well as the new terminology DATS will not be adopted until an effective date of November 2026. Despite that long wait, this paper will propose to modify the current IFATCA policies to anticipate this change.

Policy Analysis

2.7 In the following paragraphs, we will look at current IFATCA policy and see what changes need to be made to keep them current with the latest developments.

2.8 The first paragraph of IFATCA policy ADME 2.14 is:

It is proposed to amend this policy to reflect the upcoming changes to ICAO
documentation. The new text would read:

ATCOs shall not be required to provide Digital Air Traffic Service (DATS) to more than one aerodrome simultaneously.

IFATCA’s opposition to the simultaneous provision of ATS in more than one
operational environment remains unchanged.

From this point on, when discussing Remote and Virtual Towers in this paper, we will refer to the term DATS.

2.9 The second paragraph of IFATCA policy ADME 2.14 is:

The fourth paragraph reads:

Here we run into the complexity of the subject matter, as we are in a phase in which many different configurations of DATS are being developed and implemented. We can discern several different scenarios for the implementation of DATS:

1. The replacement of a conventional tower by DATS – In this case, controllers would like to be able to provide the same level of service as they are accustomed. It is currently unclear which requirements are necessary to achieve this goal. ICAO does not provide guidelines regarding the necessary system capabilities to provide DATS. It was noted by IFATCA in 2014, that these types of guidelines are crucial to the safe implementation of DATS.
   This scenario is currently covered in spirit by the IFATCA policy under review in this paper, but the wording can use some clarification.
2. The implementation of DATS to provide ATS where it previously was not available – This can be either ATC or AFIS, or both, depending on traffic mix, volume, system capability and budget. In this scenario, the new configuration is almost certainly an improvement on safety and service. There is therefore no need to develop specific policy regarding this scenario.
3. The consolidation of DATS services to multiple aerodromes in a single “Multiple Remote Tower” centre is of some worry to IFATCA. It may become attractive for ANSPs to have ATCOs that are rated to operate on more than one of the aerodromes serviced. In fact, as mentioned above, this is the most cost-effective way of operating these centres and DATS in general. In Sweden and Norway, AFIS is already provided in this manner. The consolidation of services to multiple aerodromes simultaneously would especially constitute a
   large cost-cutting measure. There are strong indications in literature (Wickens, C. D. (2002). Multiple resources and performance prediction. Theoretical Issues in Ergonomics Science, 3(2), 159–177) that such configurations carry large inherent safety risks. An example of the hazards of operating with multiple screens and voice communication systems is the incident at Überlingen (Investigation report of the accident at Überlingen, German Federal Bureau of Aircraft Accidents Investigation, May 2004, https://reports.aviation-safety.net/2002/20020701-1_B752_A9C-DHL_T154_RA-85816.pdf).
   Other issues which are of concern in Multiple Remote Tower Centres are contingency procedures and sequential provision of ATS to different aerodromes during a shift. IFATCA’s working paper “Study Remote Towers Concept” (Study Remote Towers Concept, IFATCA TOC, Gran Canaria 2014 – https://ifatca.wiki/kb/wp-2014-92/) provides more details on these issues.
   This scenario is currently covered by the IFATCA policy under review in this paper.
4. The construction of a DATS contingency tower, to replace a conventional tower in case of a failure – A contingency service where previously none existed can of course only be welcomed. However, careful consideration must be given to the capabilities and limitations of the contingency service. For example, ATCOs have to be refreshed and trained periodically in the operation and procedures of the contingency tower. ANSPs must protect ATCOs by formulating a concept of operations which takes that and other factors, into account. The limitations of the contingency tower may dictate different use of separation standards and procedures than the conventional tower.
   This scenario is not specifically covered by IFATCA policy.

2.10 It is difficult to formulate policy statements that apply universally to all these different scenarios. Aside from the different scenarios for implementation of DATS, there are also multiple concepts of operation. A fixed 360-view of an entire aerodrome and its surrounding airspace is one, but there are also systems which only display (part of) the runway and some of the taxiways and aprons. These differences can and will result in different service levels. This reality conflicts with current IFATCA policy. While many serious concerns remain about these partial configurations, TOC considers that they are being proposed and planned. In order for IFATCA and its MAs to remain a partner in these conversations, a more positive statement is proposed in this working paper.

2.11 It is proposed to strengthen the wording of the two paragraphs listed in 2.9, while at the same time acknowledging that there is no “one-size-fits-all” solution to questions of suitability of DATS systems. Too much depends on system capabilities, limitations and the local conditions pertaining to the service level provided. It is for this reason, that IFATCA has decided to expand its practical guidance material.

2.12 The third paragraph of ADME 2.14 currently reads as follows:

Most of this statement is a repeat of the second paragraph. It is therefore suggested that this paragraph is deleted, with the caveat that the word “guidance” will be added to the draft for the second paragraph.

Further, it is suggested to delete the word “separation” from the policy. The
rationale behind this change is that separation standards already exist for the tower environment. The way that ATCOs apply those separation standards may change, depending on the capability of the system which is being implemented.

Lastly, the policy is reordered slightly for readability.

The new proposed text would read as follows:

Second paragraph ADME 2.14:

When implementing DATS, standards, procedures, guidance and clear requirements shall be developed. Requirements at a minimum should include, but are not limited to:

• Surveillance equipment capable of providing the desired service level
• A robust contingency plan in case of system failure

Fourth paragraph ADME 2.14:

When replacing a conventional tower, DATS should be capable of providing the same level of service as the aerodrome control tower.

2.14 The fifth and final paragraph of ADME 2.14 reads:

We again find a slight repetition in the policy statements. For clarity and an
increased readability of the TPM, it is proposed that this statement should be split up in its parts, deleting the repetition and clarifying the remaining clauses.

The requirement for separation standards is deleted, as per the rationale mentioned above.

It is proposed to expand the statement on training programmes to specify that not only people that work directly with DATS systems require training, but also those that work in adjacent units, as their operations will be affected by the new mode of operations at the relevant aerodromes.

Standardised training requirements must be developed for all ATCOs that work directly or indirectly with DATS.

The statement on endorsements is altered to reflect the new terminology DATS. We maintain the requirement for a specific endorsement, as we consider DATS systems in general to be a type of surveillance. Aside from the system being a mode of surveillance, the mode of operation might also mean that controllers will have to adapt what form of separation to apply when handling traffic. This also means that handling traffic using DATS systems is fundamentally different to handling traffic from a conventional tower, underlining the need for the below statement.

A specific endorsement is required to operate at an aerodrome that provides DATS.

2.15 The full new revised, policy would read:

ATCOs shall not be required to provide Digital Air Traffic Services (DATS) to more than one aerodrome simultaneously.

When implementing DATS, standards, procedures, guidance and clear requirements shall be developed. Requirements at a minimum should include, but are not limited to:

• Surveillance equipment capable of providing the desired service level
• A robust contingency plan in case of system failure

DATS shall provide an equivalent or greater level of safety, compared to the previous configuration.

When replacing a conventional tower, DATS should be capable of providing an equivalent or greater level of service as the aerodrome control tower.

Standardised training requirements shall be developed for all ATCOs that work directly or indirectly with DATS.

A specific endorsement is required to operate at an aerodrome where DATS are provided.

Conclusions

3.1 IFATCA’s work on DATS is far from done. In a continually changing environment where a multitude of different systems with different capabilities are active, being implemented and being developed, it can be hard to pin down a position that is and will remain relevant.

3.2 In order to stay on top of the latest developments, IFATCA’s Remote Tower Task Force continually monitors the developments in the area of DATS. The members of this task force are also hard at work for our member associations to provide the most up-to-date information and guidance materials to educate our community.

3.3 IFATCA’s representatives at ICAO level continue to express the concerns that our members have when it comes to DATS. There are many questions that are still unanswered and we can expect that member associations will continue to be confronted with ANSPs that want to implement DATS systems that ATCOs are not comfortable working.

3.4 A continuous re-examination of IFATCA’s policies regarding DATS will have to be ongoing until best practices and standards become apparent. It is suggested to delegate this task mostly to the Remote Tower Task Force, with a TOC liaison dedicated to monitor the subject matter.

Recommendations

4.1 It is recommended that IFATCA policy ADME 2.14:

Is amended to read:

ATCOs shall not be required to provide Digital Air Traffic Services (DATS) to more than one aerodrome simultaneously.

When implementing DATS, standards, procedures, guidance and clear requirements shall be developed. Requirements at a minimum should include, but are not limited to:

• Surveillance equipment capable of providing the desired service level
• A robust contingency plan in case of system failure

DATS shall provide an equivalent or greater level of safety, compared to the previous configuration.

When replacing a conventional tower, DATS should be capable of providing an equivalent or greater level of service as the aerodrome control tower.

Standardised training requirements shall be developed for all ATCOs that work directly or indirectly with DATS.

A specific endorsement is required to operate at an aerodrome where DATS are provided.

4.2 It is recommended that DATS remain a point of attention for IFATCA, until such time as best practices and standards become apparent.

References

Digital Air Traffic Services for Aerodromes (DATS) proposals for amendments: Draft DATS PfAs, ICAO ATMOPSP November 2022.

Wickens, C. D. (2002). Multiple resources and performance prediction. Theoretical Issues in Ergonomics Science, 3(2), 159–177.

Investigation report of the accident at Überlingen, German Federal Bureau of Aircraft Accidents Investigation, May 2004, https://reports.aviation-safety.net/2002/20020701-1_B752_A9C-DHL_T154_RA-85816.pdf

Study Remote Towers Concept, IFATCA TOC, Gran Canaria 2014 –
https://ifatca.wiki/kb/wp-2014-92/