CIE Colour Orientation Tool
Plot a chromaticity coordinate (x, y) to get an oriented sense of which general aviation signal-colour family it sits nearest to — a learning aid for colour concepts, not a certification tool.
Chromaticity Coordinates
Frequently Asked Questions
Quick answers about the CIE Colour Orientation Tool and aviation signal-colour chromaticity.
Q1What does the CIE Colour Orientation Tool do?
It plots a CIE 1931 chromaticity coordinate (x, y) on the chromaticity diagram and shows which general aviation signal-colour family it sits nearest to: red, yellow, green, blue or white. It is an educational learning aid for AGL colour concepts.
Q2Can I use this tool for compliance or certification?
No. It is an orientation tool. The colour zones are an illustrative approximation and do not reproduce the current ICAO Annex 14 Attachment 1 or FAA AC 150/5345-53 chromaticity tables, which are periodically revised. Compliance testing needs calibrated photometric equipment and the exact boundary tables in the current applicable standard.
Q3What is the CIE 1931 chromaticity diagram?
It is a two-dimensional map of colour using x and y coordinates. The outer curve is the spectral locus, plotted here from the CIE 1931 2° standard observer chromaticity coordinates, and colours are located inside it.
Q4How do I plot a point?
Enter x and y coordinates and select Plot Point, choose a quick preset for a typical red, yellow, green, blue or white, or click or tap directly on the diagram. Reset clears the point.
Q5What are the colour zones based on?
They are positioned using published reference boundary equations in the style of FAR §25.1397 and SAE J578 signal-colour definitions. This is a closer approximation than a simple grid, but it is still not the current ICAO or FAA table.
Q6What does the nearest colour family result mean?
It tells you which illustrative zone your coordinate falls in, with a short description of where that colour is used in airfield lighting. It gives a sense of orientation, not a pass or fail result.
Q7Why does chromaticity matter for airfield lighting?
Colour is an important part of airport visual communication, and different systems use specified colours for different operational purposes. Evaluating colour covers chromaticity coordinates, colour boundaries, luminous intensity and colour consistency.
Q8Can chromaticity change over time?
Yes. Lens ageing and contamination can shift a fixture's chromaticity over time, which is why colour is checked as part of photometric testing and maintenance.
Q9Where can I find the exact colour boundaries?
In the current applicable standard, such as ICAO Annex 14 or FAA AC 150/5345-53. Use the exact tables in the latest edition for any compliance work.
Don't Just Check the Chromaticity. Understand the Colour Science.
This tool plots a coordinate against the signal-colour chromaticity zones.
Build the technical knowledge behind it — how the CIE 1931 colour space works, why red, white, yellow and blue boundaries are defined the way they are, how lens ageing and contamination shift chromaticity over time, and how colour compliance fits into the wider photometric system.
Check the coordinate. Understand the science. Apply it with confidence.
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Important Notice, Disclaimer & Limitation of Liability
Please read before relying on any content on this page or any result produced by it.
- Purpose and intended users. This page is an independent educational and informational reference for competent, suitably trained and authorised airfield ground lighting (AGL) and aerodrome electrical personnel, and for people learning the subject. It is not professional engineering, legal or regulatory advice, and using it does not create any professional or client relationship.
- Safety. Work on series circuits, constant current regulators (CCRs), isolating transformers, cables and connectors can be fatal. Always apply the aerodrome’s permit-to-work and isolation/LOTO procedures, prove dead, use correctly rated instruments and PPE, and follow the manufacturer’s instructions. Nothing here authorises work on live equipment or the bypassing of any safety device or interlock.
- Aviation operations. Nothing on this page authorises installation, energisation, return to service, a change of operating category, a NOTAM or any aerodrome certification decision. These rest with the aerodrome operator, the air navigation service provider and the competent regulator.
- Standards and regulations. References to ICAO Annex 14, FAA AC 150/5345-53, FAR §25.1397, SAE documents and the CIE 1931 colour space are for orientation only. They are summarised, may be incomplete or superseded, and are not official text. Consult the current official editions. Using this tool does not demonstrate compliance with any law, standard or regulatory approval, and official documents and the competent regulator always prevail.
- Illustrative content; no warranty. The diagram, zones, presets (“typical” values) and descriptions are illustrative and may contain errors or simplifications. Content and the tool are provided “as is” and “as available”, without warranty of any kind, express or implied, including accuracy, completeness, currency or fitness for a particular purpose.
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- Tool inputs. Coordinates you type, pick or click are processed in your browser. They are not sent to us or stored, and reset when you press Reset or reload the page. Please do not rely on a reading you have not checked against measured data.
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