Airfield Lighting Systems Photometric Measurement
What is Photometric Measurement?
Photometric measurement is a method of assessing light to understand its specific properties like intensity and illuminance. For airfield lighting systems, it means measuring the lights’ colour and intensity to understand if they have appropriate colour and brightness.
Isocandela Diagrams
An isocandela diagram is a graphical representation that shows the distribution of light intensity (measured in candelas) emitted by a light source in various directions.
In the context of airfield lighting, isocandela diagrams are essential for understanding that lights emit in the correct pattern and intensity to guide pilots safely. Airport operators can verify that the lights are aligned and performing properly by comparing these diagrams to the related standards.
Isocandela diagram for ALSF-2, SSALR and SSALS approach centreline lights and crossbars (white light)
Source: ADB Safegate
How to Measure Lights’ Photometric Properties
Photometric Measurement with Laboratory Equipment
Photometric measurement can be done using laboratory equipment by bringing the light fixtures to where the equipment is. This means the light fixtures must be removed from the site, which limits their use for regular lighting measurement.
However, lab photometric measurement equipment is handy to test individual fixtures to ensure they are ready to be installed. This enables airports to refurbish/repair their fixtures by ensuring compliance with standards instead of purchasing complete sets from the manufacturers. Annual airfield light repair/refurbishment savings can reach C$1.1 million (€750k or US$800k) for an airport.
Photometric Measurement with Mobile Equipment
Over time, photometric measurement equipment has improved and become suitable for mobile use. Modern equipment can be mounted on a vehicle, and measurements can be taken by passing over or near the lighting fixtures. This makes regular photometric measurements possible as it requires less runway closure time and resources.
(Left: Laboratory, Right: Mobile)
Source: Argos Ingegneria
Why is Photometric Measurement Required for Airfield Lights?
Manufacturers perform photometric measurements on airfield lights during production to ensure they meet design specifications and regulatory standards. However, the following factors make the photometric measurements a requirement after installation.
Installation Issues
Improper installation is an essential reason for photometric testing after installing airfield lights. Even if the lights are manufactured correctly, errors during installation, like incorrect alignment, can affect their performance.
Figure 4 shows the photometric measurement results of a properly installed light and an improperly installed threshold light. It can be seen that improperly installed ligth fixtures’ center of the light beam has shifted to the right, and it does not illuminate at the correct angle.
Wear and Tear
Over time, lights degrade due to weather, dirt accumulation, or aging, leading to reduced brightness or performance. Periodic testing ensures they still meet the standards.
Standards and Regulations
Various aviation authorities like ICAO, FAA, EASA and Transport Canada Civil Aviation (TCCA) have standards and regulations for regular photometric measurement of airfield lights to ensure they comply with their standards.
(Left: Proper Installation, Right: Improper Installation)
Source: ADB Safegate
River Island and Photometric Testing
At River Island, we specialize in airfield lighting and photometric testing, offering unparalleled expertise to ensure compliance, safety, and efficiency for airports. Our partnerships with industry leaders, such as Argos Ingegneria, and our team’s experience in the world’s largest and most advanced airfield lighting systems position us as a trusted resource for all your photometric needs.
Whether addressing regulatory requirements, planning system upgrades, or optimizing your maintenance processes, we are here to provide tailored solutions backed by experience and innovation.
References
Argos Ingegneria: http://www.argosingegneria.com/
ADB Safegate: Understanding Iso-candela Diagrams (Vimeo) https://vimeo.com/420603816
Relevant Articles
ICAO Standards and Photometric Testing
Canadian Regulations and Photometric Testing
FAA Standards and Photometric Testing
