---
title: "CS ADR-DSN.B.205 Radio altimeter operating area — Certification Specifications and Guidance Material for Aerodrome Design (CS-ADR-DSN) — Issue 7, Aerodromes · Avioverse"
description: "A radio altimeter operating area should be established in the pre-threshold area of a precision approach runway Category II and III, and where…"
url: "https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-b-runways/cs-adr-dsn-b-205"
---

# CS ADR-DSN.B.205 Radio altimeter operating area

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

IR Implementing rule

## CS ADR-DSN.B.205 Radio altimeter operating area

(a) A radio altimeter operating area should be established in the pre-[threshold](https://avioverse.aero/glossary/easa/threshold) area of a precision approach [runway](https://avioverse.aero/glossary/easa/runway) Category II and III, and where practicable, in the pre-threshold area of a precision approach runway Category I.

(b) Length of the area:

A radio altimeter operating area should extend before the threshold for a distance of at least 300 m.

(c) Width of the area:

A radio altimeter operating area should extend laterally, on each side of the extended centre line of the runway, to a distance of 60 m, except that, when special circumstances so warrant, the distance may be reduced to no less than 30 m if a safety assessment indicates that such reduction would not affect the safety of operations of [aircraft](https://avioverse.aero/glossary/easa/aircraft).

\[Issue: ADR-DSN/3]

IR · CS ADR-DSN.B.205 — Regulation (EU) No 139/2014 · ED Decision 2016/027/R · Aerodromes Easy Access Rules · EAR revision 13 Mar 2026

[All rules in CHAPTER B — RUNWAYS](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-b-runways)

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.