---
title: "ETSO-2C104a — CS-ETSO · Avioverse"
description: "Microwave Landing System (MLS) Airborne Receiving Equipment 1 Applicability This ETSO gives the requirements which microwave landing system (MLS)…"
url: "https://avioverse.aero/regulations/easa/cs-etso/subpart-b/etso-2c104a"
---

# ETSO-2C104a

European Technical Standard Orders (CS-ETSO) · CS-ETSO · EAR revision 1 Oct 2026

IR Implementing rule

## ETSO-2C104a

Microwave Landing System (MLS) Airborne Receiving Equipment

1 Applicability

This ETSO gives the requirements which microwave landing system (MLS) airborne receiving equipment that is manufactured on or after the date of this ETSO must meet in order to be identified with the applicable ETSO marking.

2 Procedures

2.1 General

Applicable procedures are detailed in CS-ETSO Subpart A.

2.2 Specific

None.

3 Technical Conditions

3.1 General

3.1.1 Minimum Performance Standard

Standards set forth in EUROCAE document ED-36A dated February 1995 including amendment 1 of July 1997 and amendment 2 of September 1997).

3.1.2 Environmental Standard

See CS-ETSO Subpart A paragraph 2.1

3.1.3 Computer Software

See CS-ETSO Subpart A paragraph 2.2

3.2 Specific

Radio Technical Commission for Aeronautics (RTCA) Document DO-177 (1981), used in US TSO-C104 differs from EUROCAE document ED-36A in signal acquisition warning generation and test procedures.

4 Marking

4.1 General

Marking is detailed in CS-TSO Subpart A paragraph 1.2.

4.2 Specific

None.

5 Availability of Referenced Document

See CS-ETSO Subpart A paragraph 3.

IR · ETSO-2C104a — CS-ETSO · ED Decision 2003/10/RM · CS-ETSO Easy Access Rules · EAR revision 1 Oct 2026

[All rules in SUBPART B – LIST OF ETSOs](https://avioverse.aero/regulations/easa/cs-etso/subpart-b)

Consolidated from the EASA Easy Access Rules (revision 1 Oct 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.