---
title: "GM1 ADR-DSN.M.655 Obstacle protection surface for PAPI and APAPI — Certification Specifications and Guidance Material for Aerodrome Design (CS-ADR-DSN) — Issue 7, Aerodromes · Avioverse"
description: "The displacement of the system upwind of the threshold reduces the operational landing distance."
url: "https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-m-visual-aids-for-navigation-lights/gm1-adr-dsn-m-655"
---

# GM1 ADR-DSN.M.655 Obstacle protection surface for PAPI and APAPI

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.M.655 Obstacle protection surface for PAPI and APAPI

(a) The displacement of the system upwind of the [threshold](https://avioverse.aero/glossary/easa/threshold) reduces the operational landing distance.

(b) Additional guidance on the calculation for siting PAPI/ APAPI on a [runway](https://avioverse.aero/glossary/easa/runway) with ILS/MLS is given in ICAO Doc 9157, [Aerodrome](https://avioverse.aero/glossary/easa/aerodrome) Design Manual, Part 4, [Visual Aids](https://avioverse.aero/glossary/easa/visual-aids).

\[Issue: ADR-DSN/4]

GM · GM1 ADR-DSN.M.655 — Regulation (EU) No 139/2014 · ED Decision 2017/021/R · Aerodromes Easy Access Rules · EAR revision 13 Mar 2026

[All rules in CHAPTER M — VISUAL AIDS FOR NAVIGATION (LIGHTS)](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-m-visual-aids-for-navigation-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.