45TH ANNUAL CONFERENCE, Kaohsiung, Taiwan, 27-31 March 2006
WP No. 165
Remote Control Towers
Presented by PLC
1.1 The subject of Remote Control Towers was introduced at the Hong Kong 2004 Conference by the German Member Association and subsequently added to the TOC work programme for the year 2004-2005.
1.2 Committee B decided in Melbourne to set the topic on the PLC work programme.
1.3 This WP investigates the Remote Control Tower concept from a professional viewpoint. It is related to Agenda items B.5.6 Definition of Remote Control Tower and B.5.7 Study the Virtual Tower Concept.
1.4 Conclusion 3.1 from the TOC working paper presented at Melbourne 2005 Conference states:
“In Europe and North America there is currently no use of remote aerodrome control. According to international regulations as well as national laws this is considered to be illegal”.
1.5 In Germany, the ANSP (Air Navigation Service Provider) has started Remote Tower operations last November.
2.1 Relevant ICAO documents
2.1.1 The ICAO relevant sources for Aerodrome Control and Control Towers are the following:
- Annex 11 – Air Traffic Services – § 3.2.b,
- Doc 4444 PANS-ATM – § 4.1.3; Chapter 7 and Chapter 8 § 8.10,
- Doc 9184 – Airport Planning Manual – Part I, § 8.6.2,
- Doc 9426 – ATS Planning Manual – Part III, Section 2, Chap. 2
2.1.2 None of these sources provides a definition for “Remote Control Tower” or “visual observation”.
2.1.3 Annex 11 defines in Chapter 1 “Aerodrome Control Tower” as follows:
“A unit established to provide air traffic control service to aerodrome traffic”.
Note that ICAO refers to the entity providing Aerodrome Control Service rather than to the location from where that entity is providing the service. To establish the optimum location from where that service can be provided it is necessary to examine the service to be provided.
2.1.4 Aerodrome traffic is defined as:
” All traffic on the manoeuvring area of an aerodrome and all aircraft flying in the vicinity of an aerodrome”.
2.1.5 ICAO Doc 4444 ATM describes following:
220.127.116.11 In chapter 4: General Provisions for Air Traffic Services, sub-chapter 4.1 Responsibility for the Provision of Air Traffic Control Service, paragraph 4.1.3 Aerodrome control service:
“Aerodrome control service shall be provided by an aerodrome control tower.”
and in Chapter 7. Procedures for Aerodrome Control Service, paragraph 18.104.22.168:
“Aerodrome controllers shall maintain a continuous watch on all flight operations on and in the vicinity of an aerodrome as well as vehicles and personnel on the manoeuvring area. Watch shall be maintained by visual observation, augmented in low visibility conditions by radar when available. Traffic shall be controlled in accordance with the procedures set forth herein and all applicable traffic rules specified by the appropriate ATS authority. If there are other aerodromes within a control zone, traffic at all aerodromes within such a zone shall be coordinated so that traffic circuits do not conflict.”
2.1.6 The first sentence excludes APP units and ACC units to provided aerodrome control service. The second stipulates that the aerodrome control unit must be located at such a place from where all flight operations on and in the vicinity of an aerodrome as well as vehicles and personnel on the manoeuvring area can be watched by visual observation when the weather permits.
2.2 Defining “Remote Control Tower”
2.2.1 Although ICAO doesn’t define the term “visual observation” IFATCA only accepts this as being: “observation through direct eyesight not supported by means other than optical aids (glasses/lenses) that correct vision”.
2.2.2 Consequently, a “Remote Control Tower” can be defined as:
“An aerodrome control tower from where, in visual meteorological conditions (VMC), a continuous watch on all flight operations on and in the vicinity of an aerodrome as well as vehicles and personnel on the manoeuvring area cannot be established nor maintained through visual observation.”
2.3 Existing IFATCA Policy
2.3.1 An IFATCA policy related to the need for direct visual observation already exist. IFATCA Manual, page 3 2 2 5, § 2.5, states:
|“A control tower must afford an aerodrome controller with direct visual observation of the manoeuvring area. The use of CCTV equipment (CCTV = closed-circuit television) is not acceptable as a substitute for direct visual observation”.|
2.3.2 Although this policy was not created for “remote” operational rooms, and technology evolved, offering new equipment for observation/surveillance different than CCTV, it remains relevant.
2.3.3 WP 129/96, from which the above policy has been derived, states:
“The overall task of the aerodrome controller is based upon an awareness of the movement of aircraft and vehicles by direct visual observation. The task of the aerodrome controller to control aircraft movements is a defined safety function and one that requires unobstructed visual observation from the control tower. The use of televisions and other aids to overcome deficiencies or obstructions is a short term measure to alleviate difficulties in directly visually observing aircraft movements. But, in themselves, [these] can provide an additional distraction to the controller from actually visually observing other movements of aircraft and vehicles on other parts of the manoeuvring area”.
2.3.4 This Policy together with other arguments was used to successfully argue the case for a Satellite Tower at EHAM in 2001.
2.3.5 IFATCA has also obtained that the following recommendation (# 4.5.11) was inserted in the European Action Plan for the Prevention of Runway Incursion:
“Avoid infringing sight lines from the tower and assess any existing visibility restrictions from the tower, which have a potential impact on the ability to see the runway, and disseminate this information as appropriate. Recommend improvement when possible and develop appropriate procedures”.
2.4 Safety aspects
2.4.1 As the application of the Remote Control Tower concept is too recent, there are no data to be analysed with the purpose of assessing safety.
2.4.2 A functional hazard assessment of the concept outlines the lack of visual observation by the Tower Controller, in every case where this is found to be a relevant part of the safety nets by ICAO.
2.4.3 Adopting the Reason’s Model, this can be identified as a “latent failure” at “Decision Makers” level.
2.4.4 By analysing ICAO publication, this aspect appears to be fundamental, and can only be superseded in those situations where weather affects visibility and Low Visibility Procedures (LVP) become necessary. Thence, intentionally cutting down this safety net appears to be unacceptable.
2.4.5 Moreover, statements from industry and other stakeholders, that electronic observation/surveillance is more effective than visual observation have no scientific grounds and are as such unacceptable.
2.4.6 From a Human Factors point of view, direct observation provides better situational awareness by allowing perspective vision, immediate perception of the position (azimuth and distance) and speed. The same information, provided via a label on a target, although more accurate, needs to be interpreted by the ATCO and may lead to increased human error rate in aerodrome control.
2.4.7 In addition to the control functions, aerodrome controllers have specific information providing functions that cannot be accomplished without direct visual reference to the occurrences.
2.4.8 ICAO Doc 4444 Chapter 7 Procedures for Aerodrome Control Service, sub- chapter 7.3 Information To Aircraft by Aerodrome Control Towers, paragraph 22.214.171.124 Abnormal Aircraft Configuration and Condition states that:
“Whenever an abnormal configuration or condition of an aircraft, including conditions such as landing gear not extended or only partly extended, or unusual smoke emissions from any part of the aircraft, is observed by or reported to the aerodrome controller, the aircraft concerned shall be advised without delay.”
Furthermore under subchapter 7.4 Essential Information on Aerodrome Conditions paragraph 7.4.2 states that:
”Essential information on aerodrome conditions shall include information relating to the following:
a) construction or maintenance work on, or immediately adjacent to the movement area;
b) rough or broken surfaces on a runway, a taxiway or an apron, whether marked or not;
c) snow, slush or ice on a runway, a taxiway or an apron;
d) water on a runway, a taxiway or an apron;
e) snow banks or drifts adjacent to a runway, a taxiway or an apron;
f) other temporary hazards, including parked aircraft and birds on the ground or in the air;
g) failure or irregular operation of part or all of the aerodrome lighting system;
h) any other pertinent information.
2.4.9 Because of the above IFATCA finds the concept of Remote Control Tower unacceptable.
2.4.10 Electronic observation/surveillance can assist the controller in performing his duties but only as a complement to direct visual observation.
2.4.11 Electronic derived data must be selected, redundancy avoided, information elaborated and made easily available and understandable by the ATCO. IFATCA considers that displaying high mass of data on computer or radar screens is not compliant with the operational and HF needs.
2.5 Legal Aspects
2.5.1 Annex 11 contains Standards, mandatory for Contracting States of ICAO, unless a difference have been filed and published in the annex supplement.
2.5.2 Docs 4444 only contain procedures, recommended to States for application; Doc 9184 and 9426 only provide guidance material. Therefore, their application is not mandatory for Contracting States of ICAO.
2.5.3 Legislatory and regulatory functions still remain entitled to States or to those supranational authorities to which the States have delegated it (i.e. ECAC in Europe). These can endorse or refuse the SARPs, recommended procedures and guidelines contained in ICAO documents.
2.5.4 Consequently, from a legal point of view, at the moment, the application of the concept of Remote Control Towers by Contracting States, although not sharable by IFATCA, cannot be considered illegal. The only provision to be respected is the publication of the related information in accordance to Annex 15.
3.1 The concept of “Remote Control Tower”, as defined in § 2.2.2, cannot be supported by IFATCA. “Direct visual observation”, as defined in § 2.2.1 is of vital importance to perform the control and information functions as described in Annex 11.
3.2 From a legal point of view, the application of this concept appears to not be against any international regulation, although not in accordance to recommended procedures and guidance material published by ICAO. Consequently, to give more strength to IFATCA vision on the issue, actions should be initiated to address the point to ICAO and obtain the publication of related Standards on Annex 11 and 14.
3.3 IFATCA is not against electronic means complementing direct visual observation. These means must produce elaborated information, from selected data, easily available and understandable by the Tower Controller. IFATCA considers that displaying high mass of data on computer or radar screens is not compliant with this operational and HF needs in the field of aerodrome control.
4.1 It is recommended that the EB brings the need for an aerodrome control tower to be located within visual range of the aerodrome, in order to permit direct visual observation of the area and airspace under control, to the attention of ICAO.
4.2 It is recommended that “electronic means complementing visual observation in Tower Control” be inserted in the TOC and PLC work program for the year 2006-2007.
4.3 It is recommended that the following amendment be made to the IFATCA Manual, page 4 4 1 3:
1.2.11 “Direct visual observation” is defined as “observation through direct eyesight not supported by means other than optical aids (glasses/lenses) that correct vision”.
1.2.12 An aerodrome controller cannot be held liable for any accident or incident that might occur on that portion of the aerodrome and its vicinity over which he exercise control, unless direct visual observation of the area concerned is practicable or, exclusively in relation to surface movements under Low Visibility Procedures, a surface movement surveillance system is in use.
1.2.13 A “Remote Control Tower” is defined as “An aerodrome control tower from where, in visual meteorological conditions (VMC), a continuous watch on all flight operations on and in the vicinity of an aerodrome as well as vehicles and personnel on the manoeuvring area cannot be established nor maintained through visual observation.”
1.2.14 Although the Remote Control Tower concept appears to not be against any international regulation, it is not in accordance to recommended procedures and guidance material published by ICAO. As a consequence, IFATCA opposes the Remote Control Tower Concept.
And the following paragraphs be renumbered accordingly.
Annex 11 – Air Traffic Services – § 3.2.b.
Doc 4444 PANS-ATM – § 4.1.3; Chap. 7; § 8.10.
Doc 9184 – Airport Planning Manual – Part I, § 8.6.2.
Doc 9426 – ATS Planning Manual – Part III, Section 2, Chap. 2.
European Action Plan for the Prevention of Runway Incursion – V1.1, R IFATCA Manual.
Last Update: September 29, 2020