Ground lighting for the skies

Take off and land in safety

By Morand Fachot

Air traffic safety is a complex and multi-dimensional issue. As one of its main elements, AGL (airfield ground lighting) is essential for the movement of aircraft both in the air and on the ground. IEC TC (Technical Committee) 97: Electrical installations for lighting and beaconing of aerodromes, is central to the preparation of International Standards for AGL.

Hella LED runway inset (Photo: Hella KGaA) Hella LED runway inset (Photo: Hella KGaA)

More growth in sight

Air traffic is constantly expanding and has returned to the annual growth rate it achieved before the 2008 financial crisis, as demand keeps increasing for additional passenger and freight capacity. According to data from the ACI (Airports Council International), the global trade body that represents 1 650 airports in 179 countries and territories, in 2010 its members reported handling over 5 billion passengers (up 6,6 % on 2009), 91 million metric tonnes of freight (up 15,3 %) and 74 million aircraft movements. The number of passengers is expected to double in the next 15 to 20 years.

International standards essential for safety

Air traffic safety is guided at the international level by the 1944 Chicago Convention which established the ICAO (International Civil Aviation Organization), a UN (United Nations) agency that organizes and regulates air transport. The convention (now in its ninth edition) contains annexes supported by SARPs (standards and recommended practices). SARPs are specifications that are recognized as necessary or desirable in the interests of the safety, regularity or efficiency of international air navigation. Operational requirements for AGL are specified in Annex 14 to the Chicago Convention, which applies to the design and operation of aerodromes.

AGL systems are characterized by several light units that are spread out over a relatively large area. They include all approach lights, which guide aircraft in flight during the landing phase; runway lights, which direct aircraft after they land or as they take off; taxiway lights, giving indications to crews as they manoeuvre to / from parking positions from / to runways; apron lights used in areas set aside for aircraft parking, servicing and loading; and signage that provides direction and information to taxiing aircraft and airport vehicles.

The most cost-effective AGL system design is achieved by the use of current controlled circuits (series system) instead of voltage controlled circuits. TC 97 is a pioneer in terms of preparing International Standards for series circuit systems.

Strong demand

Some of the technologies used in AGL systems are unique and all International Standards being prepared by TC 97 are genuinely new standards, for which no competing international equivalent has been identified. As a result, there is strong market demand for the Standards from engineers involved in the systems design, procurement and construction of AGL equipment.

TC 97 expects that International Standards on the installation and maintenance of the constant current series circuits will be used by regulatory bodies as reference material. TC 97 is a supplier of standards to ICAO and ACI; however, it notes "a lack of familiarity with IEC Standards in aviation circles".

Technology driving standards work

As more efficient AGL solutions based, for instance, on LEDs (light-emitting diodes) are being introduced, as well as new and more demanding operational constraints, increasingly advanced and sophisticated control and monitoring systems will be needed. TC 97 already has a PT (Project Team) working on technical requirements for AGL control and monitoring systems.

The introduction of A-SMGCS (Advanced Surface Movement Guidance and Control System) will be needed to maintain the aerodrome movement rate under all weather conditions within a specified minimum visibility limit whilst upholding the required level of safety. An advanced visual aid system is a fundamental element of an A-SMGCS and it is expected that new products will evolve from the development of such visual aid systems.

All these new systems will use existing or require new International Standards.

Present and future work

TC 97 published the second edition of its IEC 61821 International Standard, which deals with the Maintenance of AGL constant current series circuits, in September 2011.

The TC has also earmarked as a priority completing work on the IEC 61820 International Standard, setting out System design and installation requirements for the same circuits.

As air traffic increases and new technologies are being incorporated in AGL systems, TC 97 has set itself the task of updating published standards according to these new technologies as it takes "into account the continuous increase of the safety and environmental protection levels".

It also wants to seek more expert participation from countries outside Europe and to "make really effective the cooperation with International Civil Aviation organizations to promote the use of TC 97 standards".

TC 97 works closely with other IEC TCs and external organizations. It is a customer of standards from TC 20: Electric cables; TC 23: Electrical accessories; TC 34: lamps and related equipment, and its subcommittees; TC 96: Transformers, reactors, power supply units and similar products for low voltage; TC 99: Rules for system engineering and erection of electrical power installations; and CIE (International Commission on Illumination).

As air traffic for both passengers and freight soars in years to come and as new technologies are being introduced to AGL systems, demand for TC 97 work and its cooperation with other TCs and organizations is set to increase.

Runway holding position sign at Pittsburgh International Airport Hong Kong airport approach (Photo: Safegate Group)
Hella LED runway inset (Photo: Hella KGaA) Hella LED runway inset (Photo: Hella KGaA)
Safer landing with LED lights (Photo: OSRAM) Safer landing with LED lights (Photo: OSRAM)