---
title: "GM1 ADR-DSN.U.925 General — Certification Specifications and Guidance Material for Aerodrome Design (CS-ADR-DSN) — Issue 7, Aerodromes · Avioverse"
description: "It is not possible to establish specifications for colours such that there is no possibility of confusion."
url: "https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-u-colours-for-aeronautical-ground-lights/gm1-adr-dsn-u-925"
---

# GM1 ADR-DSN.U.925 General

Certification Specifications and Guidance Material for Aerodrome Design (CS-ADR-DSN) — Issue 7 · Regulation (EU) No 139/2014 · EAR revision 13 Mar 2026

GM Guidance material

## GM1 ADR-DSN.U.925 General

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](https://avioverse.aero/glossary/easa/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.

GM · GM1 ADR-DSN.U.925 — Regulation (EU) No 139/2014 · ED Decision 2014/013/R · Aerodromes Easy Access Rules · EAR revision 13 Mar 2026

[All rules in CHAPTER U — COLOURS FOR AERONAUTICAL GROUND LIGHTS, MARKINGS, SIGNS AND PANELS](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-u-colours-for-aeronautical-ground-lights)

Consolidated from the EASA Easy Access Rules (revision 13 Mar 2026, 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.