---
title: "AWO.B.CATIII.109 CS AWO.B.CATIII.109 Alert height — CS-AWO · Avioverse"
description: "(See AMC AWO.B.CATIII.109) For a fail-operational system with a DH below 15 m (50 ft) or with no DH, an alert height shall be established in accordance…"
url: "https://avioverse.aero/regulations/easa/cs-awo/subpart-b-section-4/awo-b-catiii-109"
---

# AWO.B.CATIII.109 CS AWO.B.CATIII.109 Alert height

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

IR Implementing rule

## AWO.B.CATIII.109 CS AWO.B.CATIII.109 Alert height

(See AMC AWO.B.CATIII.109)

For a fail-operational system with a DH below 15 m (50 ft) or with no DH, an alert height shall be established in accordance with CS AWO.B.CATIII.123(a) and shall be at least 30 m (100 ft).

\[Issue: CS-AWO/2]

IR · AWO.B.CATIII.109 — CS-AWO · CS-AWO Easy Access Rules · EAR revision 14 Aug 2026

AMC Acceptable means of compliance

## AMC AWO.B.CATIII.109 Alert height

(See CS AWO.B.CATIII.109)

It may be operationally useful for the alert height to be somewhat higher than 30 m (100 ft) since this would permit reversion to a higher DH in the event of system failure. A maximum value should be established during certification and it should not normally be above 90 m (300 ft).

\[Issue: CS-AWO/2]

AMC — CS-AWO · 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.