---
title: "AWO.B.CATIII.121 CS AWO.B.CATIII.121 General — CS-AWO · Avioverse"
description: "(See CS 25.1309 and its AMC, and AMC1 AWO.B.CATIII.121 and AMC2 AWO.B.CATIII.121) - (a) The effects of failures of the flight guidance system including…"
url: "https://avioverse.aero/regulations/easa/cs-awo/subpart-b-section-4/awo-b-catiii-121"
---

# AWO.B.CATIII.121 CS AWO.B.CATIII.121 General

All Weather Operations (CS-AWO) · CS-AWO · EAR revision 14 Aug 2026

IR Implementing rule

## AWO.B.CATIII.121 CS AWO.B.CATIII.121 General

(See CS 25.1309 and its AMC, and AMC1 AWO.B.CATIII.121 and AMC2 AWO.B.CATIII.121)

\- (a) The effects of failures of the flight guidance system including the navigation means (facilities external to the aircraft) shall be considered in accordance with CS 25.1309 and CS 25.1329.

\- (b) The radio altimeter (or other device capable of providing equivalent performance and integrity level), and excess-deviation alerts shall comply with CS AWO.B.CATII.120 and CS AWO.B.CATII.121 respectively.

\[Issue: CS-AWO/2]

IR · AWO.B.CATIII.121 — CS-AWO · ED Decision 2022/007/R · CS-AWO Easy Access Rules · EAR revision 14 Aug 2026

AMC Acceptable means of compliance

## AMC2 AWO.B.CATIII.121 Flight crew and maintenance checks

When exposure times relevant to failure probability calculations are dependent on flight crew and maintenance checks (i.e. preflight, first flight of the day, pre-land, etc.) and/or inspection intervals for dormant (latent) failures, these tasks, time intervals and the recommended component monitoring programme should be specified in the AFM or maintenance manual as appropriate.

\[Issue: CS-AWO/2]

FAILURE CONDITIONS

AMC — CS-AWO · ED Decision 2022/007/R · CS-AWO Easy Access Rules · EAR revision 14 Aug 2026

AMC Acceptable means of compliance

## AMC1 AWO.B.CATIII.121 Flight demonstrations of failure conditions

AMC — CS-AWO · ED Decision 2022/007/R · CS-AWO Easy Access Rules · EAR revision 14 Aug 2026

[All rules in SUBPART B -APPROACH AND LANDING SECTION 4 -AIRWORTHINESS CERTIFICATION OF AEROPLANES FOR OPERATIONS WITH DECISION HEIGHTS (DHs) BELOW 30 M (100 FT) OR NO DECISION HEIGHT (DH) -CATEGORY III (CAT III) OPERATIONS](https://avioverse.aero/regulations/easa/cs-awo/subpart-b-section-4)

Consolidated from the EASA Easy Access Rules (revision 14 Aug 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.