55TH ANNUAL CONFERENCE, Las Vegas, USA, 14-18 March 2016
WP No. 312
The Use of ATS Surveillance Data in the Provision of Non-Surveillance Services
Presented by PLC
This working paper studies the situation where a controller is provided with surveillance data but is not authorised to provide a surveillance service. The paper compares ICAO SARPs to practical applications and recommends policy requiring publication of defined rules on the use of surveillance data.
1.1. Surveillance data is provided to controller work positions for several reasons. Most commonly for the provision of air traffic control (ATC) services provided by a suitably qualified surveillance controller.
1.2. Surveillance data is also used as an assistance tool in the provision of services such as Aerodrome Control, Procedural Control and Flight Information. In applications such as these, it is quite likely that the controller or operator providing the service is not qualified to provide surveillance based control services.
1.3. At the previous IFATCA Conference in Sofia, a working paper (54th IFATCA Conference Agenda Item C6.6 “The Provision of Surveillance Approach and Aerodrome Control Services as a Combined Function” (Presented by PLC)) was presented relating to controllers performing approach and aerodrome control in a combined function. Following on from that, the request for this paper was made in response to the situation where a controller is provided with surveillance data to assist with provisions of non-surveillance services. In the absence of a clearly defined rule set, confusion exists for some controllers as to the extent at which the information can be used for and their responsibility to act on the information displayed.
1.4. Guidance from ICAO is available on the use of surveillance data and will be presented along with practical examples of how different Air Navigation Service Providers (ANSPs) are applying the ICAO requirements and how they are defining it for their controllers.
1.5. The paper will also look at liability and safety concerns that arise from the lack of clear understanding of service provision as well as potential distraction and workload issues arising from additional information that may not enhance the service being provided.
2.1. ICAO Documentation
2.1.1. ICAO has established Standards and Recommended Practices (SARPS) for licensing of Air Traffic Controllers.
Annex 1 – Personnel licensing defines the following Air Traffic Controller ratings:
|4.5 Air traffic controller ratings
Air traffic controller ratings shall comprise the following categories:
a) aerodrome control rating;
b) approach control procedural rating;
c) approach control surveillance rating;
d) approach precision radar control rating;
e) area control procedural rating; and
f) area control surveillance rating.
Additionally, ICAO recommends specific training for surveillance ratings; approach control surveillance, approach precision radar control and area control surveillance. As part of the rating, the controller must demonstrate a level of knowledge appropriate to the privileges granted in at least the following additional subjects:
1) Principles, use and limitations of applicable ATS surveillance systems and associated equipment; and
2) Procedures for the provision of ATS surveillance service, as appropriate
2.1.2 ICAO has also published guidelines, which deal with all the technical and operational aspects of Air Traffic Management. Chapter 8 of PANS-ATM (Doc 4444) – ATS Surveillance Services contains provisions on the role of surveillance in the different Air Traffic Services:
USE OF ATS SURVEILLANCE SYSTEMS IN THE AERODROME CONTROL SERVICE
22.214.171.124 When authorised by and subject to conditions prescribed by the appropriate ATS authority, ATS Surveillance systems may be used in the provision of aerodrome control service to perform the following functions:
a) flight path monitoring of aircraft on final approach;
b) flight path monitoring of other aircraft in the vicinity of the aerodrome;
c) establishing separation specified in 8.7.3 between succeeding departing aircraft; and
d) providing navigation assistance to VFR flights.
While these functions allow surveillance to be used to complement aerodrome control, ICAO also recognises that aerodrome control is, for the most part, based on visual observation of the manoeuvring area and aerodrome vicinity and qualifies the use of surveillance data with the statement:
“the appropriate ATS authority shall ensure that the availability and use of an ATS surveillance system will not be detrimental to visual observation of aerodrome traffic.”
2.1.4 Guidance for the functions of surveillance data in a procedural control service are also given in 8.7.1 (h). It specifies that surveillance can be used to maintain a watch on the progress of air traffic, in order to provide a procedural controller with:
|i) improved position information regarding aircraft under control;
ii) supplementary information regarding other traffic; and
iii) information regarding any significant deviations by aircraft from the terms of their respective air traffic control clearances, including their cleared routes as well as levels, when appropriate.
USE OF ATS SURVEILLANCE SYSTEMS IN THE FLIGHT INFORMATION SERVICE
The information presented on a situation display may be used to provide identified aircraft with:
a) information regarding any aircraft observed to be on a conflicting path with the identified aircraft and suggestions or advice regarding avoiding action;
b) information on the position of significant weather and, as practicable, advice to the aircraft on how best to circumnavigate any such areas of adverse weather (see 126.96.36.199, Note);
c) information to assist the aircraft in its navigation.
2.1.6 As shown above, ICAO provides clear guidelines on the role of surveillance data within Aerodrome Control, Procedural Control and Flight Information services. The functions are deliberately quite limited in accordance with the desire to minimise interference with the prime role. This gives clear direction to States who can then choose to adopt or develop their own procedures.
2.1.7 What is not quite so clear is any requirement for aircraft identification prior to providing the service. PANS-ATM prescribes that before providing an ATS surveillance service an aircraft must be identified via one of the listed identification methods. PANS-ATM also lists identification methods that an Aerodrome Controller may use to identify aircraft, although it makes no specific requirement that an aircraft must be identified prior to using the surveillance data.
For the Flight Information Service, however, aircraft must be identified prior to being provided with information from a situation display. PANS-ATM is not clear whether a Flight Information Service Officer (FISO) can make that identification themselves or whether they have to rely on a transfer of identification from a suitably qualified controller.
2.1.8 PANS-ATM also provides some specifications as to the capabilities of the ATS Surveillance System. While technical capabilities are beyond the scope of this paper it is worthwhile noting that the ICAO requirements pertain to systems used in the provision of Air Traffic Services in general. Therefore, Flight Information Services should be afforded surveillance data of the same quality as air traffic control services.
8.1.1 ATS surveillance systems used in the provision of air traffic services shall have a very high level of reliability, availability and integrity. The possibility of system failures or significant system degradations which may cause complete or partial interruptions of service shall be very remote. Backup facilities shall be provided.
2.2.1 Various regulators and ANSPs around the world have adopted these procedures or modified them to suit their local operation. While this paper will focus on the global approach of ICAO, it is worth noting that some states have filed differences from ICAO SARPs. The European Aviation Safety Agency (EASA) has established the Aerodrome Control Instrument (ADI) rating with the possibility of an Aerodrome Radar Control (RAD) endorsement. While this rating and endorsement vary from ICAO the actual application does not (Commission Regulation (EU) No. 805/201).
|The aerodrome Radar (RAD) endorsement recognizes that radar is playing an increasing role in the provision of Aerodrome Control. The additional skills required are limited to those required to provide the RAD service described in ICAO Procedures for Air Navigation Services (European Manual of Personnel Licensing – Air Traffic Controllers).|
2.2.2 In Australia while the regulator, Civil Aviation Safety Authority (CASA) aligns with ICAO in terms of ratings, aerodrome controllers in certain towers are allowed to use surveillance data to separate aircraft. The authority for this comes with the specific local endorsement and Air Services Australia provides suitable training that fulfils the ICAO requirements.
2.2.3 Eurocontrol follows the ICAO SARPs quite rigidly in their Aerodrome Flight Information Service (AFIS) manual, however, it leaves the onus on the regulator of each jurisdiction to authorise and prescribe conditions on its use.
2.2.4 In the provision of AFIS, the use of surveillance data is limited to performing the following functions:
|a) flight path monitoring of aircraft on final approach;
b) flight path monitoring of other aircraft in the vicinity of the aerodrome;
c) Providing navigation assistance to VFR flights.
2.2.5 A further subsection details that an aircraft must be identified prior to providing a surveillance service and it details several identification methods. A disclaimer is then included that the use of an ATS surveillance system in the provision of flight information service does not relieve the pilot-in-command of an aircraft of any responsibilities.
2.2.6 Airways New Zealand (Airways), the state ANSP, has developed procedures that generally meet the ICAO PANS-ATM requirements. The New Zealand regulator, Civil Aviation Authority of New Zealand (CAA), allows surveillance data to be used to assist in the provision of Aerodrome and Approach Procedural Control. CAA documentation (Aviation Information Publication New Zealand – Vol.1 ENR 1.6-15) also contains a very clear brief of what service is being provided.
|ATC surveillance service is NOT provided by non-radar ATC units. Therefore at a control tower where an aerodrome control service, or aerodrome/approach procedural control service is provided, aircraft are not continuously monitored on surveillance displays.|
2.2.7 Airways have expanded and clarified the usage in their Manual of Air Traffic Services (Airways New Zealand Manual of Air Traffic Services) with procedures that sit within the ICAO SARPs and provisions. Surveillance data is provided in towers for the purpose of improving controller situational awareness, reducing routine RT and performing certain functions within the ATM platform. Tasks usually associated with surveillance control service including flight path monitoring are precluded. Some of these tasks are allowable under the ICAO Annexes and PANS, however, Airways have chosen to further limit the use. They then clearly define the limitations, which makes the responsibilities and requirements clear for controllers. For these controllers, Airways provide surveillance equipment training as part of aerodrome and procedural approach control rating/validation training.
2.2.8 The use of surveillance data in the provision of Flight Information Services is not allowed by Airways and they provide no specialised training related to surveillance systems to FISO’s. This is another example where Airways have placed additional restrictions (in this case chosen not to adopt) and have clearly defined that.
2.2.9 However, FISO’s are provided with the same situation display as an aerodrome controller and are required to interact with it as part of their duties. This poses a dilemma, as it is likely that more up to date and accurate information is available via surveillance than that which they source by other means. Even the basic surveillance data that is displayed at the CWP is unable to be used to assist in their primary role, the provision of traffic information.
2.2.10 While local uses vary, one element is consistent with the ICAO SARPS. That the use of ATS surveillance data should not distract from the core functions of the service being provided.
2.3.1 As stated in the introduction, this paper originated from concern at situations where a controller is provided with surveillance data but no directive or training as to its use or even rules that prohibit the use of available information. In some cases this has created an expectation that the information will be used and the controller is therefore left unsure as to their own liability if they chose to act on or not act on the information displayed.
2.3.2 Where no clear rule set is defined, the controller has no clear directive of what service he/she can or cannot provide nor does the pilot have certainty on the level of service to expect. Provision of services beyond that which is required can, over time, create an expectation of service and given that the level of service provided may well vary depending on the controller on duty it is possible that pilots could be expecting a level of service that they are not receiving which generates a serious safety concern.
2.3.3 The lack of universal regulation on the liability of air traffic controllers means that any issue of liability will be left to national laws to determine. Judicial systems and legislation vary in different countries and it is therefore difficult to predict how liability issues may be treated. Duty of care is only relevant in some jurisdictions, however, it is an often used term. In order to determine if there has been a breach of the duty of care, first the standard of care must be established. One of the measures of standard of care is that of the reasonably competent ATCO. Where the rule set is not defined, and reasonably competent ATCOs are providing varying levels of service, it is difficult to assess the standard of care expected. If the issue is not clearly described it will fall to the judiciary to determine, on the evidence before it at the time, the appropriate standard of care applicable.
2.3.4 The clearer the rule set prescribed by the regulator or provider, the clearer the expectation of service for both controller and pilot. ICAO PANS-ATM already provides much of the material required to establish such a rule set. Establishing and complying with prescriptive rules on the use of surveillance data is the best chance of avoiding prosecution given the indeterminate nature of controller liability.
2.3.5 Situations where the surveillance data serves no purpose (e.g. Flight Information in New Zealand) are another example of the potential safety issues of providing superfluous information. The surveillance data has no function in the service and instead has the potential to cause distraction.
2.3.6 The question remains that if surveillance data provides no enhancement to the service, is there a legitimate need for the information? Or, where there are rules preventing use of the information, should a reasonable ANSP be providing the surveillance data at all?
3.1 ICAO has defined air traffic controller ratings that identify what service(s) the holder is authorised to perform. ICAO also defines some additional training required for surveillance ratings.
3.2 ICAO also provides guidance as to the role of surveillance data in relation to specific Air Traffic Services.
3.3 ICAO provides no guidance as to the liability of air traffic controllers and national laws will likely determine liability. Clarity can be provided, although, not with absolute certainty if the role of surveillance data in the controller’s duties is clearly defined.
3.4 The lack of a clearly defined rule set can also raise safety concerns when there are differences in the expected level of service between pilot and controller.
4.1. It is recommended that IFATCA policy is:
Where ATS Surveillance Data is provided to assist in the provision of an Air Traffic Service, rules on the use, restrictions and limitations of the surveillance data shall be published, so that legal responsibilities are clear and unambiguous.
And is included in the IFATCA Technical and Professional Manual.
4.2. It is recommended that IFATCA policy is:
Controllers who are required to use surveillance data shall be provided with suitable training in ATS Surveillance Systems.
And is included in the IFATCA Technical and Professional Manual.
UKCAA CAP774 – UK Flight Information Services
IFATCA WP No. 158 The Provision of Surveillance Approach and Aerodrome Control Services as Combined Function Sofia, Bulgaria 2015
The Legal Liability of Air Traffic Controllers, Chrystel Erotokritou
The Civil Liabilities of Air Traffic Control Personnel in New Zealand, Rick Bigwood
Head Down Time in Aerodrome Operations: A Scope Study April, 2004 Brian Hilburn, Ph.D.
Last Update: October 1, 2020