Aerodrome – Review Provisional Policy on Future ATM Concepts for the Provision of Aerodrome Control Service

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Aerodrome – Review Provisional Policy on Future ATM Concepts for the Provision of Aerodrome Control Service

46TH ANNUAL CONFERENCE, Istanbul, Turkey, 16-20 April 2007

WP No. 87

Aerodrome – Review Provisional Policy on Future ATM Concepts for the Provision of Aerodrome Control Service

Presented by TOC

Summary

Several Member Associations are facing a tremendous change regarding Tower Control. The big change lies in new ATM Concepts for the provision of Aerodrome Control Service. Various of these concepts, e.g. Remote Tower Concept and the Virtual Tower Concept, have been on the agenda for the last two years and in Kaohsiung 2006 Provisional Policy was accepted. After further research and discussion, the Technical and Operations Committee (TOC) concludes that ICAO documentation currently appears to only allow for an Aerodrome Control Service to be provided at the airport and based on visual observation as primary means of maintaining a continuous watch. Other concepts can only be introduced if all relevant ICAO Docs and Annexes are reviewed and SARPs are published that support it. Besides this a number of requirements have been identified that have to be met before IFATCA can support the concept.

Introduction

1.1  Several Member Associations (MAs) have been confronted with new Aerodrome Control Service Concepts. Many of these new concepts are mainly driven by cost reductions, as centralizing multiple Tower Units at one location has many financial benefits.

1.2  New Aerodrome Control Service Concepts have been on the agenda of Committee B for the last two years, as the Virtual Tower and the Remote Tower concept can be considered as new Aerodrome Control Service Concepts.

1.3  Committee B tasked the Technical and Operations Committee (TOC) to continue work on these concepts, as the tremendous change in Tower Control needs to be studied extensively. While discussions progressed, it became clear that the Professional and Legal Committee (PLC) had to be included in this further studying of the subject, as Professional issues need to be considered as well.

1.4  IFATCA Provisional Policy on future ATM Tower Concepts was accepted at the Kaohsiung conference in 2006. This policy is twofold, addressing both Visual Observation and future concepts. The working paper produced by PLC (C.6.12) will address the first part of this policy, while this paper will focus on requirements for future concepts. The Policy on this subject is reviewed and a list of requirements is recommended for inclusion in the IFATCA Manual.

Discussion

2.1 Known new Aerodrome Control Service Concepts

2.1.1  The Swedish Virtual Tower project has developed into two separate projects:

  • The purpose of the first project Remote Operational Tower (ROT) is to evaluate if this concept is workable. The work has started in November 2006, by studying the infrastructure and exploring the possibility of installing cameras, monitors and microphones at the airport that has been selected for the trial.
  • The second project, Advanced Remote Tower (ART), takes the ROT as starting point and will study a more (technological) advanced concept. The Swedish Air Traffic Service Provider (ATSP) has put in a request for subsidy with the 6th EU framework.

2.1.2  The German Remote Tower concept (see WP93 of Melbourne 2005) is basically Tower Control from another Tower by a controller who has responsibility for both the working environment. Surveillance is provided to the controller by position reports, later enhanced by the use of cameras and microphones.

A trial at night time was conducted, and had on average 4 movements per night. A number of issues were identified (e.g. lighting of the airport and surveillance) and some changes made. It has now ended and was rated by the German ATSP as very successful.


2.2  IFATCA Provisional policy is:

“Any future ATM concept for the provision of Aerodrome Control Service, is only acceptable to IFATCA, provided that;

  • When direct visual observation is replaced by alternative means, it must be as good as, or better than direct visual observation; and
  • In addition to standard fall back procedures for Aerodrome control units, appropriate fall back procedures must be implemented in case of failure of any technical device influencing the situational awareness of aerodrome controllers.”

 


2.3  ICAO

2.3.1 ICAO PANS ATM Doc 4444 states in chapter 7 para 7.1.1.2.:

“that 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.”

Any new concept that introduces another form of watch on the aerodrome, e.g. through cameras, cannot be introduced before contingency procedures are developed and introduced. Without these procedures, the controller might not be able to keep a continuous watch on all flight operations, with its possible safety implications.

Chapter 7 para 7.3.1.4:

“In the event the aerodrome controller, after a take-off clearance or a landing clearance has been issued, becomes aware of a runway incursion or the imminent occurrence thereof, or the existence of any obstruction on or in close proximity to the runway likely to impair the safety of an aircraft taking off or landing, appropriate action shall be taken as follows:

a) Cancel the take-off clearance for a departing aircraft.

b) Instruct a landing aircraft to execute a go-around or missed approach.

c) In all cases inform the aircraft of the runway incursion or obstruction and its location in relation to the runway.”

Chapter 7 para 7.3.1.6.1:

“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.“

Chapter 7 para 7.4.4:

“When a not previously condition pertaining to the safe use by aircraft of the manoeuvring area is reported to or observed by the controller, the appropriate aerodrome authority shall be informed and operations on that part of the manoeuvring area terminated until otherwise advised by the appropriate aerodrome authority.”

The observation of an Aerodrome Controller is always important to the safe operations on and in the vicinity of an aerodrome. This observation becomes crucial when it comes to abnormal circumstances, and the time-factor also becomes increasingly important. If Aerodrome Control will be provided from an alternative location, which would imply that current ICAO rules and regulations are not followed, or changed, then the controller is not able to observe these abnormal situations by eyesight through the windows of the Aerodrome Control Tower. This would imply that the delay in getting the information to the controller must be no more than under normal circumstances, in order to ensure a fast response. It is important that the controller is provided with at least the same level of surveillance, in order to live up to his or her responsibilities.

2.3.3. ICAO PANS ATM Doc 4444 Chapter 7 para 7.5.3.2.3.2.:

“When communications by a system of visual signals is deemed to be adequate, or in the case of radio communication failure, the signals given hereunder shall have the meaning indicated therein.

Light signal from aerodrome control Meaning
Green flashes Permission to cross landing area or to move onto taxiway
Steady red Stop
Red flashes Move off the landing area or taxiway and watch out for aircraft
White flashes Vacate manoeuvring area in accordance with local instructions

ICAO PANS ATM Doc 4444 Chapter 7 para 7.5.3.2.3.3.:

“In emergency conditions or if the signals in 7.5.3.2.3.2 are not observed, the signal given hereunder shall be used for runways or taxiways equipped with a lighting system and shall have the meaning indicated therein.

Light signal Meaning
Flashing runway or taxiway lights Vacate the runway and observe the tower for light signal

ICAO Aerodromes Annex 14 para 5.1.3.1.:

“A signalling lamp shall be provided at a controlled aerodrome in the control tower.”

There is a necessity for the controller to have the option to transmit optical signals to aircraft both in the air and on the ground and to personnel and cars on the manoeuvring area. The transference must be stabile and trustable. If Aerodrome Control will be provided from an alternative location, this might mean that the controller is not situated at the airport, or in a position from where these signals cannot be observed by aircraft. This again would imply that ICAO Docs and Annexes should be reviewed and SARPs must be published to support these operations.


2.4 Safety

2.4.1  All states under ICAO Air Traffic Services Annex 11 are required to establish a safety programme in order to achieve an acceptable level of safety in the provision of ATS. What is this acceptable level of safety? How is proven that this change to procedure and systems meets this?

ICAO Air Traffic Services Annex 11, 2.26.3 details the necessary requirements to locally manage safety. This includes the establishment of a safety management system including;

  • identifying safety hazards;
  • providing continuous monitoring and regular assessment of the safety level achieved, and
  • aims to make continuous improvement to the overall level of safety.

2.4.2  It also details the procedure for significant safety related change; ICAO Air Traffic Services Annex 11, 2.26.5:

“Any significant safety-related change to the ATS system, including the implementation of a reduced separation minimum or a new procedure, shall only be effected after a safety assessment has demonstrated that an acceptable level of safety will be met and users have been consulted. When appropriate, the responsible authority shall ensure that adequate provision is made for post-implementation monitoring to verify that the defined level of safety continues to be met.”

Note. — When, due to the nature of the change, the acceptable level of safety cannot be expressed in quantitative terms, the safety assessment may rely on operational judgment.

2.4.3  ICAO PANS ATM Doc 4444 provides further guidance for safety management in ATS. Inter alia, safety management in ATS should include the following: Safety assessments in respect of the planned implementation of airspace reorganization, the introduction of new equipment, systems, or facilities, and new or changed ATS procedures;

2.4.4 If the procedure does not come under the provision of ICAO, then the local regulator has to approve it. In this case the local regulator will use the guidance from ICAO Air Traffic Services Annex 11 and ICAO PANS ATM Doc 4444. They will have to be convinced that the procedure is an improvement of overall safety and that the full safety management system procedures are followed. Such a safety management system shall ensure that actual and potential hazards can be identified, necessary remedial actions implemented and that continued monitoring ensures that an acceptable level of safety is being achieved.


2.5 Professional Aspects

2.5.1  IFATCA Policy on Automation/Human Factors is:

“Automation must improve and enhance the data exchange for controllers. Automated systems must be fail-safe and provide accurate and incorruptible data. These systems must be built with an integrity factor to review and crosscheck the information being received.

The Human Factors aspects of Automation must be fully considered when developing automated systems.

Automation must assist and support ATCOs in the execution of their duties. The controller must remain the key element of the ATC system.

Total workload should not be increased without proof that the combined automated/human systems can operate safely at the levels of workload predicted, and to be able to satisfactorily manage normal and abnormal occurrences.

Automated tools or systems that support the control function must enable the controller to retain complete control of the control task in such a way so as to enable the controller to support timely interventions when situations occur that are outside the normal compass of the system design, or when abnormal situations occur which require non-compliance or variation to normal procedures.”

 

The Policy above clearly indicates the need for the human to be involved in all developments in automation and to remain the key element of the system. It is obvious that the most effective way to achieve this is to involve current operational controllers in all stages of developments.

2.5.2  The aspects of legal liability and responsibility for incidents must be clarified if automation is part of the Aerodrome Control Service Concept. Training must be completed prior the use of any automated system, because human must be able to monitor the automated system in any situation. Any automated system associated with a new Aerodrome Control Service Concept must be designed to be simple to learn and operate by its users.


2.6 Providing the controller with ‘the complete picture’

2.6.1. Aerodrome Controllers perform several duties when providing Aerodrome Control Service. These duties support the controller in maintaining a continuous watch and providing service to the users. By performing these duties, the controller is able to keep ‘the complete picture’ and to maintain situational awareness. Further study is required if there is a need to come up with a list of functional requirements.


2.7 Minimum Requirement List

2.7.1  TOC and PLC agreed, when discussing this subject, that listing the requirements for New Aerodrome Control Service Concepts has added value. This list of requirements is extensive and can change over time as developments progress. At this stage, the following requirements have been identified as some of the most important:

2.7.2  Surveillance provided to the controller

If Aerodrome Control Service is provided from an alternative location and the controller is not able to survey its area of responsibility by looking through the windows of the Aerodrome Control Tower, then the surveillance provided to the controller must be at least at the same level of surveillance as currently provided by visual observation. TOC and PLC, when discussing this subject, identified a number of operational situations (e.g. night time and low visibility) in which the controllers ability to undertake his or her duties are enhanced by the use of electronic means.

2.7.3  Safety

The introduction of new Aerodrome Control Service Concepts must be subjected to a full safety analysis and relevant safety levels must be met.

2.7.4  Contingency Procedures

Any new Aerodrome Control Service Concept must have proper contingency procedures in place. The information that is sent to the controllers working environment must be presented to the controller with a minimum delay. Specific procedures, such as the back up for communication by using a signalling lamp, need to be reviewed and addressed.

2.7.5  Involvement of operational controllers in developments

The concept of Aerodrome Controllers providing ATS from another location than the Control Tower is a major change in ATC. To safeguard that the new working conditions and procedures are acceptable, workable, and functional to the controller, TOC and PLC are of the opinion that involvement of operational controllers in these developments is of the utmost importance.

Conclusions

3.1 Before any Aerodrome Control Service Concept can be endorsed by IFATCA, the following requirements shall be met:

  • The controller shall be provided with at least the same level of surveillance as currently provided by visual observation;
  • The introduction of Aerodrome Control Service Concepts shall be subject to a full safety analysis and relevant safety levels shall be met; and
  • Contingency procedures shall be in place;
  • Controllers shall be involved in the development of Aerodrome Control Service Concepts.

3.2. Currently, ICAO documentation appears to only allow for an Aerodrome Control Service to be provided at the airport and based on visual observation as primary means of maintaining a continuous watch. New Concepts can only be introduced if all relevant ICAO Docs and Annexes are reviewed and SARPs are published that support it.

Recommendations

It is recommended that;

4.1  IFATCA Provisional policy on page 3222 of the IFATCA Manual:

Any future ATM concept for the provision of Aerodrome Control Service, is only acceptable to IFATCA, provided that;

  • When direct visual observation is replaced by alternative means, it must be as good as, or better than direct visual observation; and
  • In addition to standard fall back procedures for Aerodrome control units, appropriate fall back procedures must be implemented in case of failure of any technical device influencing the situational awareness of aerodrome controllers. 

is deleted.

4.2  IFATCA Policy is:

Before any Aerodrome Control Service Concept can be endorsed by IFATCA, the following requirements shall be met:

  • The controller shall be provided with at least the same level of surveillance as currently provided by visual observation;
  • The introduction of Aerodrome Control Service Concepts shall be subject to a full safety analysis and relevant safety levels shall be met; and
  • Contingency procedures shall be in place;
  • Controllers shall be involved in the development of Aerodrome Control Service Concepts. 

and is included on page 3222 of the IFATCA Manual.

Last Update: September 29, 2020  

April 11, 2020   349   Jean-Francois Lepage    2007    

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