Working with Unserviceable or Inadequate Equipment

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Working with Unserviceable or Inadequate Equipment

39TH ANNUAL CONFERENCE, Marrakech, Morocco, 6-10 March 2000

WP No. 161

Working with Unserviceable or Inadequate Equipment


At the IFATCA 1999 (Santiago) Conference, Committee C accepted Working Paper 160 and placed its subject on the SC4 work programme. SC4 decided that because the paper had been accepted without any opposition to the points raised, policy could be derived directly from the working paper without further discussion. However, as the Santiago WP 160 would not be fresh in delegates’ minds in Marrakech the Introduction and Discussion segments of that paper have been reproduced as the DISCUSSION section of this paper. A new set of conclusions has been included in this paper addressing only those issues relevant to SC4. Comments on the legal aspects were left for SC7 to review.


Note: Reproduced from Parts 1 & 2 From Santiago WP160.

Several MAs have raised the question about the types, quality and serviceability of the equipment they are expected to use when undertaking their role as controllers. This matter is especially valid for many African and South American MAs, but also affects controllers globally.

Regardless of any particular Region or MA, all controllers are expected to make use of a variety of equipment that ranges from basic radio sets to sophisticated computer processed radar systems and data acquisition systems. Indeed, the continued and use of enhanced technology to undertake even the most simple tasks of a controller require us to consider the use of that equipment, especially when maintenance is infrequent and the equipment is unreliable and subject to failure.

Although there is existing IFATCA policy on the use of automated aids and systems, there is a need to consider the use of existing systems as well as the introduction of ‘new’ systems.

The legal responsibility of the controller also needs to be examined when the controller is required to work with equipment that is poorly maintained or is subject to irregular functioning.

The safety aspects of the provision of Air Traffic Services needs to be considered, especially when poorly maintained or inadequate equipment hinders the controller in the execution of his task, or causes increased workload and stress.

There are many problems facing controllers, today, and not all of them are related to aircraft and traffic growth. Relationships with management, concerns over remuneration, career and training prospects, all feature in controllers’ daily lives. Management is continually seeking to achieve better cost controls and more efficiency as providers of Air Traffic Services. Traffic growth continues and with limited resources available, many Providers have been pressed to assume that technology and automation will provide the answers they seek.

There may be valid reasons for introducing modern technology into the ATC working environment. Such equipment can assist controllers in the execution of their tasks, enhance safety and provide genuine increases in the ability of controllers to handle more traffic. The equipment may enable the controller to provide a more flexible and efficient service that meets the demands of the airlines. However, there is also the basic need of the controller to be provided with ‘tools’ to enable them to undertake their everyday tasks safely and efficiently. A need to be provided with equipment that enhances the way they deal with existing demands, regardless of predicated increases in traffic levels. In many areas, the lack of suitable equipment is limiting the ability of controllers to provide the service required and is giving the airlines and pilots the impression that the ATC Service is just ‘not up to the job’. In many ATC units, the equipment provided is out of date, unreliable and in no way reflects the investment that airlines have made in procuring and installing the most modern technology in their respective airline fleets.

We are already aware of the situation in many parts of the world, where inadequate equipment limits the ability of controllers to undertake even the basic tasks of communication and co- ordination with other ATC Units and ACCs. Where communication between aircraft and ATC units is difficult because of poor radio coverage. Where lack of radar systems over large areas and in busy traffic environments, have changed the purpose for the carriage of airborne conflict alert systems, such as TCAS, from a last stop safety net into a mandatory airborne traffic alert system that pilots rely on because they lack confidence in the ATC Service. It could be said that the move by Airlines to promote and introduce the “Free Flight Concept” is as much directed as the lack of adequate ATC Service as it is to meet the demands and flexibility of the airlines want for increased efficiency in any given airspace.

What is surprising, is that Airlines continue to pay the enroute charges, even though the ATC Service provided to them is inadequate or, in some places, non-existent. The adoption of TIBA for use by aircraft in parts of Africa serves the purpose of identifying the priorities of airlines and pilots. Rather than demand improvements in the ATC Service, or boycott the routes they use, the airlines and aircrew have adopted TIBA and TCAS in order for them to continue flying through airspace which has a poor or very limited Air Traffic Service.

Therefore, there should be a mandatory requirement that ensures that controllers will be provided with essential and appropriate equipment in order for them to undertake their role with confidence and precision, and to enhance safety, flexibility and the efficient use of airspace. Even though this equipment may be most basic in nature, such as a simple radio set, it has to be acknowledged that the provision of appropriate equipment is an essential tool for that controller to achieve the safety and efficiency that is expected of the modern ATC Service.

Having provided the equipment, it must also be accepted that the reliability of that equipment requires maintenance and support. Regrettably, even in the most up to date ATC systems, the failure of any part of ATC related equipment can cause significant disruption to the ATC Service and can lead to increased workload and stress, and may even impinge on the safety of flights. This matter becomes ever more important when more sophisticated equipment, such as automated systems using computerised processing, is introduced into the working environment.

Although some systems and equipment may support or back up a controller, in some cases the use of that equipment may be the essential tool to maintain a safe and reliable ATC Service. It may be essential for communication (radio), or for identification (SSR), or for assuring a safe and expeditious service to flights (radar, conflict alert systems, automatic flight progress strip printers, VDUs, computer systems, etc).

Whenever equipment is used, there is often a task requirement or, indeed, a natural reaction to place reliance on that equipment. If the equipment is a necessary and mandatory aid to the provision of that ATC Service, then that reliance becomes dependence. Once controllers become dependent on a piece of equipment, or a particular system of operation, important task orientated and safety aspects rely on the serviceability of that equipment or system.

It is becoming increasingly important to recognise the Human Factors aspects of the controller’s tasks. Not just for stress and workload, but also to examine how a controller interacts with any equipment provided. Further, evaluation of a controller’s performance should take into account what benefits might be achieved if equipment was updated or new equipment brought into use. The use of a Human Factors audit would be useful in examining the task of a controller and assessing how various types of equipment can assist and enhance the controllers’ workload, efficiency and overall safety.

When controllers are faced with unreliable equipment it is natural for them to expect it to be fixed or replaced. It is also natural to expect that a maintenance section will be established to keep equipment operational and regularly checked for accuracy. However, it is often the case that new equipment will be installed without any resources provided to keep that equipment up and running. It is unreasonable to expect an ATC unit to continue to function with long lasting unserviceabilities, especially when that equipment is essential to the ‘normal’ operation of that unit.

Unreliable and irregular functioning of equipment can distract controllers. Such equipment should be taken out of service immediately, but it is natural for controllers to try and continue using that equipment, especially if is essential to assist the normal ATC operations. This is a very ‘grey’ area and one that can lead to serious incidents occurring. Controllers should be very circumspect about using such equipment and should focus on the safety aspects associated with its continued use. Indeed, such equipment should be removed from use, even if that directly affects the Air Traffic operations.

When equipment is withdrawn from use, controllers should ensure that due notification is effected to warn aircraft, especially if the equipment directly relates to normal flight operations. Pilots must be made aware of essential unserviceabilities to landing and approach aids and also be informed if limitations on the provision of Air Traffic Services occur because of equipment unserviceability.

When controllers continue to use irregular functioning equipment, or continue to provide a ‘normal’ type of Air Traffic Services when equipment failure occurs, they must take note of how the unserviceability of ATC equipment affect their tasks and their legal responsibilities. Controllers need to be aware that they are the ones being exposed to liability if they continue to use unreliable equipment, or continue to work when equipment fails, unless they have clearly identified the limitations of their service and have it acknowledged by aircrew.

When unserviceable equipment is not repaired, controllers should ensure that any limitations of their Air Traffic Services is brought to the attention of their management and national authority. If the equipment failure seriously impedes or limits the safe provision of an Air Traffic Service, and if local management and national regulatory authorities continue to ignore the concerns of controllers, then it would be prudent for MAs to raise the matter directly with ICAO, IATA and IFALPA through IFATCA.

Controllers should be able to rely on International organisations to support the establishment and maintenance of efficient and safe ATC systems. Although controllers can highlight problems in any particular country or area, they are not always able to apply pressures to the appropriate national authority in the same way that International organisations are able to do. Controllers should also expect IATA and IFALPA to recognise any problems and rather than circumvent them, apply pressure on the national authorities to remedy the situation.

Although ICAO has recently introduced a safety audit to Member States, it does not presently review the provision of Air Traffic Services and only applies to those States who invite ICAO to undertake the audit. Regardless of which, it still remains the responsibility of the national authority to take note of any audit and to act upon it. It is not a mandatory requirement.

Existing IFATCA Policy states (IFATCA Manual page and para reference indicated):

On the general provision of equipment for the ATC task:

Air traffic controllers should be provided with ATC equipment commensurate with their operational requirements so as to promote an optimum level of safety. (Page 4122 para 2.4.2)

States be encouraged to make the maximum use of both primary radar and SSR, not only to assist pilots with RTF Failure, but also to minimise the penalties which may otherwise be imposed on other traffic. (page 3244 para 4.4)

IFATCA is concerned that TIBA procedures may be used to circumvent industrial disputes, or as a substitute for proper Air Traffic Services, rather than to overcome short- term technical problems. IFATCA provisional policy, therefore, is “State Authorities should be required to give adequate notification of the introduction of Traffic Information Broadcasts (TIBA) procedures, i.e. at least 3 months in advance, except where catastrophic events preclude this notification. TIBA procedures should only be introduced where there are significant technical and/or practical deficiencies in the ATS infrastructure, subject to the Authorities providing adequate procedures, and for a limited duration only not exceeding 6 months.” (page 324 11 para 4.8)


On the provision of automated systems:

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. (page 4123 para 2.5.1)

Automation must assist and support ATCOs in the execution of their duties, to improve performance and reduce workload, to remove non-essential tasks, to increase efficiency, to enhance not only the job satisfaction of the controller, but also the safety element of the controller’s task. (page 4123 para 2.5.2)


On the subject of legal responsibility:

The legal aspects of a controller’s responsibilities must be clearly identified when working with automated systems. (page 4123 para 2.5.5)

A Controller shall not be held liable for incidents that may occur due to the use of inaccurate data if he is unable to check the integrity of the information received.
(page 4123 para 2.5.6)

In the event of corruption or non delivery of any ATC clearance or flight safety critical transmission due to interference of RTF from any source which results in an incident or accident, the controllers concerned shall not be held liable providing that proper procedures have been followed and that all reasonable measures to overcome the problem, if known to exist, have been taken. (page 4413 para 1.2.9)

Member Associations shall bring to the attention of their national administration details of any persistent disruptive RTF interference in order that a full investigation may be conducted, and appropriate action taken. (page 4413 para 1.2.10)

Member Associations shall urge their national administration to devise contingency plans for the continued safe operation of ATC within their own or delegated airspace when a frequency or frequencies are unavailable due to interference. (page 4413 para 1.2.11)


On Occupational Stress, as far as it is affected by the limitations of equipment:

Occupational stress is the product of complex interaction of the task, the operational environment and the personality characteristics of the individual. Thus it is difficult to generalise to all controllers groups. (page 4221 para 2.3.2)

Nevertheless, some of the most common stressors have been identified as:

a) Demand

number of aircraft under control – peak traffic hours – extraneous traffic – unforeseeable events – proficiency checks/examinations;

b) Operating procedures

time pressure – having to bend the rules – feeling of loss of control – fear of consequences of errors; and

c) Working tools

limitations and reliability of equipment – VDT, RTF and telephone quality – equipment layout. (page 4222 para 2.3.3)


As can be seen from that above, existing IFATCA Policy is somewhat limited to the general provision of “serviceable” equipment. Consideration is needed to consider Policy for the continuation to provide an ATC Service with inadequate, irregular functioning or unserviceable equipment. Consideration may also be required for Policy to ensure that any equipment provided is adequately maintained and that standby equipment is provided to ensure the maintenance of Air Traffic Services and the safety of flights.

Although reference is made to automation and automated systems, the legal liabilities of continuing to provide a ‘normal’ Air Traffic Services with inadequate, irregular functioning or unserviceable equipment are not clearly stated in IFATCA Policy.

Although existing IFATCA Policy states the need for controllers to be provided with appropriate equipment to undertake their task, it might be useful to establish new Policy to endorse the responsibility of management, or national authorities, to ensure equipment provided to their controllers is supported by a maintenance organisation and is well maintained.


As can be read above, Santiago WP 160 contained a great deal of detail and argument. The term “degraded mode” has been introduced into this paper as it also covers the more subtle forms of unserviceability to which modern computerised systems are prone.

From the Professional point of view, Santiago WP 160 has been summarised as follows:

  1. Air Traffic Controllers should be provided with equipment appropriate to the task they are required to carry out.
  2. Equipment provided should have an instantaneous back-up facility;
  3. Controllers should receive adequate initial and recurrent training in degraded mode operations;
  4. Equipment provided must be regularly maintained to ensure availability and reliability;
  5. ATS providers must provide adequate and efficient fault reporting procedures and publish required repair times;
  6. Controllers should not use equipment that is known to be unserviceable, unreliable or inaccurate for the provision of services to air traffic.

Bullet point 1 Is adequately covered on Page 4 1 2 2 of the IFATCA Manual Para. 2.4.2:

“Air traffic controllers should be provided with ATC equipment commensurate with their operational requirements so as to promote an optimum level of safety.”



In the IFATCA Manual insert new policy at Page 4122, new paragraph 2.4.3, 2.4.4, 2.4.5, 2.4.6, and 2.4.7. Re-number current paragraph 2.4.3. as 2.4.8.

New Para. 2.4.3.:

“ATC equipment provided should include back-up secondary equipment on hot stand-by for use if the primary equipment becomes degraded.”

New Para. 2.4.4.:

“Controllers should be given initial and recurrent training in the degraded mode operations of their equipment.”

New Para. 2.4.5.:

“ATS management must ensure that ATS equipment is regularly maintained, by properly trained and qualified technical staff, to ensure its availability and reliability.

New Para. 2.4.6.:

“ATS management must design adequate fault reporting procedures and publish required rectification times.”

New Para. 2.4.7.:

“Air Traffic Controllers should not use equipment that is known to be unserviceable, unreliable or inaccurate for the provision of services to air traffic.”


IFATCA Manual.

Santiago Working Paper 160.

Last Update: September 28, 2020  

March 11, 2020   836   Jean-Francois Lepage    2000    

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