---
title: "GM1 ADR-DSN.Q.840 Objects to be marked and/or lighted within the lateral boundaries of the obstacle limitation surfaces — Certification Specifications and Guidance Material for Aerodrome Design (CS-ADR-DSN) — Issue 7, Aerodromes · Avioverse"
description: "The marking and/or lighting of obstacles is intended to reduce hazards to aircraft by indicating the presence of the obstacles."
url: "https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-q-visual-aids-for-denoting-obstacles/gm1-adr-dsn-q-840"
---

# GM1 ADR-DSN.Q.840 Objects to be marked and/or lighted within the lateral boundaries of the obstacle limitation surfaces

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.Q.840 Objects to be marked and/or lighted within the lateral boundaries of the obstacle limitation surfaces

(a) The [marking](https://avioverse.aero/glossary/easa/marking) and/or lighting of obstacles is intended to reduce hazards to [aircraft](https://avioverse.aero/glossary/easa/aircraft) by indicating the presence of the obstacles. It does not necessarily reduce operating limitations which may be imposed by an [obstacle](https://avioverse.aero/glossary/easa/obstacle).

(b) Other objects inside the obstacle limitation surfaces should be marked and/or lighted if a safety assessment indicates that the object could constitute a hazard to aircraft (this includes objects adjacent to visual routes e.g. waterway or highway).

(c) Overhead wires, cables, etc., crossing a river, waterway, valley or highway should be marked and their supporting towers marked and lighted if a safety assessment indicates that the wires or cables could constitute a hazard to aircraft.

(d) An autonomous aircraft detection system may be installed on or near an obstacle (or group of obstacles such as wind farms) within or outside the lateral boundaries of the obstacle limitation surfaces. This system is designed to operate the lighting only when it detects an aircraft approaching the obstacle, to reduce light exposure to local residents. Additional guidance on the design and installation of an autonomous aircraft detection system is available in the ICAO Doc 9157, [Aerodrome](https://avioverse.aero/glossary/easa/aerodrome) Design Manual, Part 4, [Visual Aids](https://avioverse.aero/glossary/easa/visual-aids).

The inclusion of this guidance is not intended to imply that such a system has to be provided.

\[Issue: ADR-DSN/3]

\[Issue: ADR-DSN/6]

GM · GM1 ADR-DSN.Q.840 — Regulation (EU) No 139/2014 · ED Decision 2022/006/R · Aerodromes Easy Access Rules · EAR revision 13 Mar 2026

[All rules in CHAPTER Q — VISUAL AIDS FOR DENOTING OBSTACLES](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-q-visual-aids-for-denoting-obstacles)

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.