Annex 14 — Aerodromes Volume I

APPENDIX 1. COLOURS FOR AERONAUTICAL GROUND LIGHTS, MARKINGS, SIGNS AND PANELS
1. General
Introductory Note.— The following specifications define the chromaticity limits of colours to be used for aeronautical ground
lights, markings, signs and panels. The specifications are in accord with the 1983 specifications of the International Commission
on Illumination (CIE).
It is not possible to establish specifications for colours such that there is no possibility of confusion. For reasonably certain
recognition, it is important that the eye illumination be well above the threshold of perception, that the colour not be greatly
modified by selective atmospheric attenuations and that the observer’s colour vision be adequate. There is also a risk of
confusion of colour at an extremely high level of eye illumination such as may be obtained from a high-intensity source at very
close range. Experience indicates that satisfactory recognition can be achieved if due attention is given to these factors.
The chromaticities are expressed in terms of the standard observer and coordinate system adopted by the International
Commission on Illumination (CIE) at its Eighth Session at Cambridge, England, in 1931.*
2. Colours for aeronautical ground lights
2.1 Chromaticities
2.1.1 The chromaticities of aeronautical ground lights shall be within the following boundaries:
CIE Equations (see Figure A1-1):
a) Red
Purple boundary y = 0.980 – x
Yellow boundary y = 0.335
b) Yellow)
Red boundary y = 0.382
White boundary y = 0.790 – 0.667x
Green boundary y = x – 0.120
c) Green
Yellow boundary x = 0.360 – 0.080y
White boundary x = 0.650y
Blue boundary y = 0.390 – 0.171x
d) Blue
Green boundary y = 0.805x + 0.065
White boundary y=0.400-x
Purple bondary x=0.600y+0.133
e) White
Yellow boundary x = 0.500
Blue boundary x = 0.285
Green boundary y = 0.440
and y = 0.150 + 0.640x
Purple boundary y = 0.050 + 0.750x
and y = 0.382
f) Variable white
Yellow boundary x = 0.255 + 0.750y
and x = 1.185 – 1.500y
Blue boundary x = 0.285
Green boundary y = 0.440
and y = 0.150 + 0.640x
Purple boundary y = 0.050 + 0.750x
and y = 0.382
Note. — Guidance on chromaticity changes resulting from the effect of temperature on filtering elements is given in the
Aerodrome Design Manual, part 4
2.1.2 Recommendation.— Where dimming is not required, or where observers with defective colour vision must be able to
determine the colour of the light, green signals should be within the following boundaries:
Yellow boundary y = 0.726 – 0.726x
White boundary x = 0.650y
Blue boundary y = 0.390 – 0.171x
2.1.3 Recommendation.— Where increased certainty of recognition is more important than maximum visual range, green
signals should be within the following boundaries:
Yellow boundary y = 0.726 – 0.726x
White boundary x = 0.625y – 0.041
Blue boundary y = 0.390 – 0.171x
* See CIE Publication No. 15, Colorimetry (1971).

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2.2 Discrimination between lights

2.2.1 Recommendation.— If there is a requirement to discriminate yellow and white from each other, they should be
displayed in close proximity of time or space as, for example, by being flashed successively from the same beacon.
2.2.2 Recommendation.— If there is a requirement to discriminate yellow from green and/or white, as for example on exit
taxiway centre line lights, the y coordinates of the yellow light should not exceed a value of 0.40.
Note.— The limits of white have been based on the assumption that they will be used in situations in which the characteristics
(colour temperature) of the light source will be substantially constant.
2.2.3 Recommendation.— The colour variable white is intended to be used only for lights that are to be varied in intensity,
e.g. to avoid dazzling. If this colour is to be discriminated from yellow, the lights should be so designed and operated that:
a) the x coordinate of the yellow is at least 0.050 greater than the x coordinate of the white; and
b) the disposition of the lights will be such that the yellow lights are displayed simultaneously and in close proximity to the
white lights.
2.2.4 The colour of aeronautical ground lights shall be verified as being within the boundaries specified in Figure A1-1 by
measurement at five points within the area limited by the innermost isocandela curve (isocandela diagrams in Appendix 2 refer),
with operation at rated current or voltage. In the case of elliptical or circular isocandela curves, the colour measurements shall be
taken at the centre and at the horizontal and vertical limits. In the case of rectangular isocandela curves, the colour measurements
shall be taken at the centre and the limits of the diagonals (corners). In addition, the colour of the light shall be checked at the
outermost isocandela curve to ensure that there is no colour shift that might cause signal confusion to the pilot.
Note 1.— For the outermost isocandela curve, a measurement of colour coordinates should be made and recorded for review
and judgement of acceptability by the appropriate authority.
Note 2.— Certain light units may have application so that they may be viewed and used by pilots from directions beyond that
of the outermost isocandela curve (e.g. stop bar lights at significantly wide runway-holding positions). In such instances, the
appropriate authority should assess the actual application and if necessary require a check of colour shift at angular ranges
beyond the outermost curve
2.2.5 In the case of visual approach slope indicators and other light units having a colour transition sector, the colour shall be
measured at points in accordance with 2.2.4, except that the colour areas shall be treated separately and no point shall be within
0.5 degrees of the transition sector.
3. Colours for markings, signs and panels
Note 1.— The specifications of surface colours given below apply only to freshly coloured surfaces. Colours used for markings,
signs and panels usually change with time and therefore require renewal.
Note 2.— Guidance on surface colours is contained in the CIE document entitled Recommendations for Surface Colours for
Visual Signalling — Publication No. 39-2 (TC-106) 1983.
Note 3.— The specifications recommended in 3.4 below for transilluminated panels are interim in nature and are based on the
CIE specifications for transilluminated signs. It is intended that these specifications will be reviewed and updated as and when
CIE develops specifications for transilluminated panels.
3.1 The chromaticities and luminance factors of ordinary colours, colours of retro-reflective materials and colours of
transilluminated (internally illuminated) signs and panels shall be determined under the following standard conditions:
a) angle of illumination: 45°;
b) direction of view: perpendicular to surface; and c) illuminant: CIE standard illuminant D65.
3.2 Recommendation.— The chromaticity and luminance factors of ordinary colours for markings and externally illuminated
signs and panels should be within the following boundaries when determined under standard conditions.
CIE Equations (see Figure A1-2):

a) Red
Purple boundary y =0.345– 0.051x
White boundary y =0.910– x
Orange boundary y =0.314+ 0.047x
Luminance factor f3 = 0.07 (mnm)
b) Orange
Red boundary y =0.285+ 0.100x
White boundary y =0.940– x
Yellow boundary y =0.250+ 0.220x
Luminance factor f3 = 0.20 (mnm)

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c) Yellow
Orange boundary Y = 0.108+0.707X
White boundary Y = 0.910-X
Green boundary Y= 1.35X – 0.093
Luminance factor β = 0.45 (mnm)
d) White
Purple boundary y = 0.010+x
Blue boundary y = 0.610-x
Green boundary y = 0.030+x
Yellow boundary y = 0.710-x
Luminance factor β = 0.75 (mnm)
e) Black
Purple boundary y = x-0.030
Blue boundary y = 0.570-x
Green boundary y = 0.050+x
Yellow boundary y = 0.740-x
Luminance factor β = 0.003(max)
f) Yellowish green
Green boundary y = 1.317x + 0.4
White boundary y = 0.910 – x
Yellow boundary y = 0.867x + 0.4
Note.— The small separation between surface red and surface orange is not sufficient to ensure the distinction of these
colours when seen separately.
3.3 Recommendation.— The chromaticity and luminance factors of colours of retro-reflective materials for markings, signs
and panels should be within the following boundaries when determined under standard conditions.
CIE Equations (see Figure A1-3):
a) Red
Purple boundary y = 0.345-0.051x
White boundary y = 0.910-x
Orange boundary y = 0.314+0.047x
Luminance factor β = 0.03(mnm)
b) Orange
Red boundary y = 0.265 +0.205x
White boundary y = 0.910 –x
Yellow boundary y = 0.207+0.390x
Luminance factor β = 0.14 (mnm)
c) Yellow
Orange boundary y = 0.160+0.540x
White boundary y = 0.910-x
Green boundary y = 1.35x-0.093
Luminance factor β = 0.16 (mnm)
d) White
Purple boundary y=x
Blue boundary y = 0.610-x
Green boundary y = 0.040+x
Yellow boundary y 0.710-x

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Luminance factor β = 0.27 (mnm)

e) Blue
Green boundary y = 0.118+0.675x
White boundary y = = 0.370-x
Purple boundary y = 1.65x-0.187
Luminance factor β = 0.01 (mnm)
f) Green
Yellow boundary y = 0.711-1.22x
White boundary y = 0.243+0.670x
Blue boundary y = 0.405-0.243x
Luminance factor β = 0.03 (mnm)
3.4 Recommendation.— The chromaticity and luminance factors of colours for transilluminated (internally illuminated) signs
and panels should be within the following boundaries when determined under standard conditions.
CIE Equations (see Figure A1-4):
a) Red
Purple boundary y = 0.345 – 0.051x
White boundary y = 0.910 – x
Orange boundary y = 0.314 + 0.047x
Luminance factor β = 0.07 (mnm)
(day condition)
Relative luminance 5% (mnm)
to white (night 20% (max)
condition)
b) Yellow
Orange boundary y = 0.108 + 0.707x
White boundary y = 0.910 – x
Green boundary y = 1.35x – 0.093
Luminance factor β = 0.45 (mnm)
(day condition)
Relative luminance 30% (mnm)
to white (night 80% (max)
condition)
c) White
Purple boundary y = 0.010 + x
Blue boundary y = 0.610 – x
Green boundary y = 0.030 + x
Yellow boundary y = 0.710 – x
Luminance factor f3 = 0.75 (mnm)
(day condition)
Relative luminance 100%
to white (night
condition)
d) Black
Purple boundary y = x – 0.030
Blue boundary y = 0.570 – x
Green boundary y = 0.050 + x

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Yellow boundary y = 0.740 – x

Luminance factor β = 0.03 (max)
(day condition)
Relative luminance 0% (mnm)
to white (night 2% (max)
condition)

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Figure A1-1. Colours for aeronautical ground lights

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Figure A1-2. Ordinary colours for markings and externally illuminated signs and panels

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Figure A1-3. Colours of retro-reflective materials for markings, signs and panels

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Figure A1-4. Colours of transilluminated (internally illuminated) signs and panels

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