---
title: "CS 25.1397 Colour specifications — CS-25 · Avioverse"
description: "Each position light colour must have the applicable International Commission on Illumination chromaticity co-ordinates as follows:"
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-f/cs-25-1397"
---

# CS 25.1397 Colour specifications

Large Aeroplanes (CS-25) · CS-25 · EAR revision 26 Jan 2023

IR Implementing rule

## CS 25.1397 Colour specifications

Each position light colour must have the applicable International Commission on Illumination chromaticity co-ordinates as follows:

(a) Aviation red –

‘y’ is not greater than 0·335; and ‘z’ is not greater than 0·002.

(b) Aviation green –

‘x’ is not greater than 0·440–0·320y;

‘x’ is not greater than y–0·170; and ‘y’ is not less than 0·390–0·170x.

(c) Aviation white –

‘x’ is not less than 0·300 and not greater than 0·540;

‘y’ is not less than ‘x–0·040’ or ‘yo–0·010’, whichever is the smaller; and ‘y’ is not greater than ‘x+0·020’ nor ‘0·636–0·400x’; Where ‘yo’ is the ‘y’ co-ordinate of the Planckian radiator for the value of ‘x’ considered.

IR · CS 25.1397 — CS-25 · ED Decision 2003/2/RM · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

[All rules in SUBPART F – EQUIPMENT](https://avioverse.aero/regulations/easa/cs-25/subpart-f)

Consolidated from the EASA Easy Access Rules (revision 26 Jan 2023, extracted 13 Oct 2026) for convenience. Not the official publication — verify against the Official Journal of the European Union and the EASA publications before operational use.