Aeronautical Ground Lighting

Ferran Balcells offers a guide to Aeronautical Ground Lighting and an insight into the role that ICAO has played in its development.

Aeronautical Ground Lighting (AGL) is the collective denomination for the whole set of ground installed luminaires and related ancillaries meant to be used as visual aids by aircraft pilots and eventually, other users of aerodrome facilities.

Specifically, AGL is formed by a number of aeronautical ground lights, arranged in accordance with precise patterns. An aeronautical ground light is any light specially provided as an aid to air navigation, other than a light displayed on an aircraft.

International standards applicable to AGL were first established by the International Civil Aviation Organisation (ICAO). Nowadays, both the European Committee for Electrotechnical Standardisation (Comité Européen de Normalisation Electrotechnique, CENELEC) and the International Electrotechnical Commission (IEC) have dedicated Technical Committees that have published a number of International and European standards regarding AGL.

The AGL system and its components

The whole AGL system encompasses the lighting of runways, including their approaches, and associated taxiways and aprons.

The lighting subsystems related to the runway include approach; visual approach path indicators; runway threshold, edge, end, and as required by operations minima, touchdown zone and centre line.

With regard to surface movement, other subsystems could be necessary, such as taxiway edge or centre line lights, stop bars, runway guard lights and all the plethora of signs, either informative or mandatory.

Luminaires and associated electrical devices

AGL is composed of luminaires plus their supporting structures, related civil engineering works, such as foundations, as well as power supplies. Since the light sources used by the luminaires are usually electric lamps (normally halogen incandescent bulbs), power supplies provide the proper electrical power to lamps.

The lamps are connected to and powered by an electrical circuit. The luminous output of a series of incandescent lamps of a given rated power is dependent on the current flowing through their filaments. Hence constant current in the circuit means constant luminous intensity. That is why the AGL circuits are traditionally configured as constant current series circuits.

The constant current is provided by a specific power supply, the constant current regulator (CCR), which powers the series circuit. This circuit is composed of:

• the proper cable, normally high voltage cable,
• the isolating series transformers, usually one per each luminaire, that isolates the low voltage or luminaire side from the high voltage primary circuit fed by the CCR. Isolating transformers also provide continuity to the series circuit in case a lamp is burned out.

The role of ICAO

ICAO was formed by the Convention on International Civil Aviation. The Convention was signed at Chicago on 7 December 1944 and came into effect upon ratification by the first 26 Member States on 4 April 1947. By the end of 1996 the Convention had been ratified by 185 States.

The Convention established a framework where international civil aviation could be developed in a safe and orderly manner.

The objective allocated to ICAO was to develop the principles and techniques of international air navigation and to foster the planning and development of international air transport so as to:

• ensure the safe and orderly growth of international civil aviation throughout the world,
• encourage the arts of aircraft design and operation for peaceful purposes,
• encourage the development of airways, airports and air navigation facilities for international civil aviation,
• meet the needs of the peoples of the world for safe, regular, efficient and economical air transport,
• prevent economic waste caused by unreasonable competition,
• ensure that the rights of contracting States are fully respected and that every contracting State has a fair opportunity to operate international airlines,
• avoid discrimination between contracting States,
• promote the safety of flight in international air navigation,
• promote generally the development of all aspects of international civil aeronautics

ICAO strategic action plan

The current ICAO strategic action plan was first adopted by ICAO’s Council on 7 February 1997 and updated on 12 June 2000.

It includes eight strategic objectives, the second of which requires the Organisation to develop and adopt new or amended Standards, Recommended Practices (SARPs) and associated documents in a timely manner to meet changing needs. One of the key activities intended to achieve this strategic objective is to maintain the currency of eighteen existing Annexes to the Convention and develop new Annexes as required. To that end, one of the issues to be addressed is “restructuring of Annexes to ensure that Annex material is restricted to essential requirements and formulated in broad terms”.

ICAO requirements

Operational requirements are essential requirements. They are the highest level. They establish what is strictly necessary so that the components of AGL provide the service they are supposed to. As an example we could mention the essential or operational requirements for stop bar lights: they have to be unidirectional, visible only within the angle and in the direction towards the runway they are protecting, and radiating red light of the intensity required by the prevailing visibility conditions.

Operational requirements have to refer to all the issues that are important for the AGL to interface with aircraft pilots.

Operational requirements are essential for the design (configuration, colour and diagram of radiation described in terms of isocandela diagrams), installation (tolerances applicable to configuration and the resulting actual diagram of radiation, surface temperature of inset lights and frangibility of elevated lights), operation (maximum surface temperature) and maintenance (field photometric measurement) of AGL. All of them are the sole competence of ICAO and are covered by its SARPs, Standards and Recommended Practices that are obligatory for every Contracting State.

The SARPs on AGL are prepared by Visual Aids groups that work under the authority of the Air Navigation Commission (ANC), currently the Visual Aids Working Group (VAWG) and formerly the Visual Aids Panel (VAP). According to the VAWG work programme, new developments expected in the field of electrical systems are new technologies in light sources (such as LED), approach lighting configurations, helicopter operations, obstacle marking and lighting and especially Advanced Surface Movement Guidance and Control Systems.

ICAO also publishes guidance material, additional to SARPs, aimed at explaining the rationale behind the requirements and how to implement them. The guidance material is contained in manuals that merely present explanations and good engineering practices and are not intended to be considered mandatory requirements.

With regard to AGL, the key manuals are three parts of the Aerodrome Design Manual (ADM), i.e., Part 4 Visual Aids, Part 5 Electrical Systems, and Part 6 Frangibility. Part 4 has been updated recently. Part 5 is undergoing review. Part 6 is expected to be published shortly.

Technical requirements of AGL

These are the requirements that translate to the real engineering world the operational requirements by means of a technical specification, encompassing suitable tests along with the corresponding approval or rejection criteria.

Technical requirements are the object of the Standardisation Organisations that follow.
Some of the Contracting States developed a number of standards or regulations on AGL, encompassing technical requirements.

The best, comprehensive example that could be mentioned is the impressive collection of specifications issued by the Federal Aviation Administration (FAA) of the United States of America. They cover equipment, operation, maintenance, etc.

Except for the FAA, national regulations were in most cases minimal and intended for public procurement purposes. This was also applicable to European States.

The short history of a European initiative

Given the lack of European standards on AGL, The European Committee for Electrotechnical Standardisation (Comité Européen de Normalisation Electrotechnique CENELEC or CLC), conducted a survey in the early 1990s to determine the scope of existing National Standards or Rules on AGL within every State, if any, and the need for them that was felt by member States.

The absence of real National Standards gave birth to CENELEC Task Force BTTF 72-3, responsible for the development of European Standards in the field of AGL. The background for the establishment of BTTF 72-3 was both the need expressed by the member States and the difficulties experienced in applying existing standards, written for low voltage installations, to the constant current series circuit.

BTTF 72-3 developed five ENV (European pre – standards) before the ongoing work was transferred in 1995 to the recently created IEC TC 97 as a result of agreements between both International Electrotechnical Standardisation Organisations.

CENELEC BTTF 72-3 has become Technical Committee number 97 (CLC TC 97) and is about to publish two new European Standards: one on Selective switching and individual monitoring of lights and the other on Advanced visual guidance docking systems.

European Standards (EN) are in principle, voluntary. They could become obligatory for certain organisations if they are given that status by a European Directive. This is the case for EN’s on AGL: as a result of Directives 93/38/CEE and 92/13/CEE, they are obligatory for public procurement purposes.

Worldwide international standards: history and role of IEC

On 15 September 1904, delegates to the International Electrical Congress, being held in St. Luis, USA, adopted a report that included the following words: ”… steps should be taken to secure the co-operation of the technical societies of the world, by the appointment of a representative Commission to consider the question of the standardisation of the nomenclature and ratings of electrical apparatus and machinery”. As a result, the International Electrotechnical Commission (IEC) was officially founded in 1906, in London, UK, where its central office was set up. The first President of the IEC was British scientist Lord Kelvin.

In 1948, the IEC Central Office moved from London to Geneva, Switzerland, where its field of action expanded to cover electronic equipment.

International standards within the IEC are prepared by specific Technical Committees (TC), which are assigned precise terms of reference and where individuals appointed by their respective National Electrotechnical Committees work in co-operation.

IEC Standards are in principle, voluntary.

Technical Committee number 97 (TC 97), Electrical installations for lighting and beaconing of aerodromes, was established in 1994, evolving from standardisation work in CENELEC Task Force BTTF 72-3. According to its Strategic Policy Statement, IEC TC 97:

• is tasked with the preparation of international standards for the design, installation, operation and maintenance of aeronautical ground lighting of aerodromes, with the caveat that operational requirements for aeronautical ground lights are specified in Annex 14 to the Convention on International Civil Aviation (Volume I, Aerodrome Design and Operations),
• will not cover electrical installations already standardised by IEC TC 64, luminaires not used as aeronautical ground lights standardised by IEC TC 34 and special cables for the constant current series circuit standardised by IEC TC 20; and
• covers requirements which apply to the whole system, from the incoming power to the aerodrome up to and including the luminaires used in aeronautical ground lighting.

It is worth noting that many of the experts have been engaged at the same time in work for both TC 97 and ICAO’s groups dealing with visual aids.

IEC publications prepared by TC 97 and published so far are listed below:

Equipment specifications

• IEC 61822, Electrical installations for lighting and beaconing of aerodromes – Constant Current Regulators. (International Standard)
• IEC 61823, Electrical installations for lighting and beaconing of aerodromes – AGL Series Transformers. (International Standard)
• IEC/TS 61827, Electrical installations for lighting and beaconing of aerodromes – Characteristics of inset and elevated luminaires used on aerodromes and heliports (Technical Specification).

Operation and maintenance

• IEC 61821, Electrical installations for lighting and beaconing of aerodromes – Maintenance of aeronautical ground lighting constant current series circuits. (International Standard). This international standard applies to the maintenance of AGL constant current series circuits and concentrates on providing the appropriate safety procedures. It is mainly concerned with safety of persons.
• IEC/TS 62143, Electrical installations for lighting and beaconing of aerodromes – Aeronautical ground lighting systems. Guidelines for the development of a safety life – cycle methodology.

This technical specification is based on the safety life – cycle methodology described in IEC 61508.

According to the parallel voting procedure between IEC and CLC, International Standards IEC 61822 and IEC 61823 have been adopted as EN in the European Union. Hence they are to be considered mandatory for public procurement purposes (see end of 5.2 above).

Conclusion

The highest level of International Standards of AGL is the competence of ICAO.

IEC develops International Standards on AGL, containing technical requirements. So does CENELEC within Europe.

International Standards are expected to be developed for the future, concerning both operational and technical requirements, in the field of electrical systems, new technologies in light sources (such as LED) and, especially, Advanced Surface Movement Guidance and Control Systems.

Ferran Balcells Serra

Ferran Balcells Serra Aeronautical Engineer (Faculty of Aeronautical Engineering, Polytechnic University, Madrid, 1974) Head of the Standardisation and Maintenance Division, Directorate of Infrastructures Aena (Spanish Airports and Air Navigation.

Member of the ICAO Visual Aids Working Group (VAWG). Chairman of IEC TC 97.

Head of the Airport Visual Aids Laboratory and other similar positions.

Involved in international standardisation as ICAO Visual Aids Panel (VAP) member of the Airport Operations Group (AOPG) of ICAO Europe and North Atlantic Region, member of CENELEC BTTF 72-3 and IEC TC 97 from their early stages.

Ministry of Transport

Head of the Airport Visual Aids Laboratory. Responsible for Studies, Projects and Standardisation (until the creation of Aena, in 1991)

Participating in international standardisation with regard to visual aids in the Visual Aids Panel (VAP) of the International Civil Aviation Organisation (ICAO). Adviser to the VAP member nominated by Spain since 1987.

Motor Ibérica S.A. (private automotive company)

Mechanical design engineer. Responsible for the design of moving train and balancing units of reciprocating internal combustion engines (until 1978).