***The version of this document available here is being updated and is expected to be released in 2012 as EASA AMC (Acceptable Means of Compliance) 20-18***

This guidance material has been prepared for the installation and certification of Mode S SSR for Elementary Surveillance. It does not constitute a regulation but does establish an acceptable means that can be used to obtain airworthiness approval of Mode S systems. Revision 1 of this guidance material takes account of Amendment 77 to ICAO Annex 10 Volumes III and IV, July 2002.

This guidance material from EASA (European Aviation Safety Agency) has been prepared for the installation, certification and maintenance of Mode S SSR transponder systems for Enhanced Surveillance. It does not constitute a regulation but it does provide a method by which equipment installers and aircraft operators can satisfy an authority that the transponder capability required by airspace regulations has been addressed.

Note:
1. This advisory material supersedes and replaces JAA TGL N°. 18 and NPA 20-12a.
2. It is practice for EASA to group AMCs together; AMC 20-13 begins on Page 30 of this 45 page PDF.

The purpose of the Guidance Document for MEL Policy is to give operators the guidance necessary to develop the MEL provisions for equipment, and conditions for its unserviceability, in order that JAR-OPS 1 and 3 and JAR-MMEL/MEL are properly complied with. Application of this TGL should ensure a harmonisation of MELs among JAA operators and assist Authorities in the MEL evaluation and approval. However, TGL 26 is guidance material only, and should not be used to overwrite the MMEL unless specifically agreed with the operator's Authority.

This is an "open letter" outlining the EASA position regarding the modification and certification of aircraft required to meet the European airspace mandate for Mode S Elementary Surveillance (ELS) and Mode S Enhanced Surveillance (EHS). It addresses questions such as;

- Which aircraft are required to have Mode S EHS?
- Who can modify my aircraft?
- What are the Certification Requirements for Mode S ELS and EHS?

and also deals with some of the most common certification problems.

Volume III of Annex 10 contains Standards and Recommended Practices and guidance material for various air-ground and ground-ground voice and data communication systems. Volume IV contains Standards and Recommended Practices and guidance material for secondary surveillance radar (SSR) and airborne collision avoidance systems (ACAS), including SARPs for SSR Mode A, Mode C and Mode S; and the technical characteristics of ACAS.

Volume IV of Annex 10 contains Standards and Recommended Practices and guidance material for secondary surveillance radar (SSR) and airborne collision avoidance systems (ACAS), including SARPs for SSR Mode A, Mode C and Mode S; and the technical characteristics of ACAS.

This document describes applications of the SSR Mode S system defined in Annex 10, Volume IV, which are known as Mode S specific services. The document defines data formats for application using Mode S specific services that can be accessed by a separate dedicated interface to the Mode S air-ground data link (subnetwork).

This standard describes an Air Traffic Control Radar Beacon System/Mode Select (ATCRBS) airborne transponder. The ATCRBS is made up of airborne transponders and ground interrogator-receivers, processing equipment and antenna systems.

Mark 4 Air Traffic Control Transponder (ATCRBS/MODE S) describes an Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) airborne transponder with Extended Interface Functions (EIF). The ATC surveillance system is made up of airborne transponders and ground interrogator-receivers, processing equipment, and antenna systems.

This document updates DO-181B by incorporating appropriate material to recognize changes made by ICAO to the Mode S System SARPs and the Mode S Subnetwork SARPs.

This document updates DO-218A by incorporating appropriate material to recognize changes made by ICAO to the Mode S System SARPs and the Mode S Subnetwork SARPs.

This document specifies the minimum operational performance requirements for Secondary Surveillance Radar Mode S Transponders.

Mode S Specific Applications provide data exchange between the ground and aircraft systems. ED-101 relates to the Dataflash application. Dataflash relies on the aircraft system and announces when parameters have changed. Therefore, regular interrogations are not needed to check these parameters.

This document specifies the minimum performance requirements of the Multilateration (MLAT) System which is one of the co-operative sensors for use in an A-SMGCS. It uses a number of receivers and/or receiver/interrogators in precisely surveyed locations in or around an airport, according to the airport layout, coverage area and the positional accuracy required. The system uses Mode S “squitter” and does not require any additional aircraft equipment to be installed.