scope:

Purpose of this Characteristic

This characteristic describes a standard Mark 4 Air Traffic Control Transponder (ATCRBS/Mode S) with Extended Interface Functions (EIF). The document defines equipment capable of supporting Traffic Alert and Collision Avoidance System (TCAS) functions, and advanced surveillance capabilities defined by the International Civil Aviation Organization (ICAO) as CNS/ATM, Automatic Dependent Surveillance-Broadcast (ADS-B), Extended (112-bit) Squitter, and the enhanced Surveillance capabilities provided by the ICAO definitions in the Manual on Mode S Specific Services are supported. This unit is specifically designed for installation in commercial transport type aircraft.

This characteristic also provides design guidance for the development and installation of a Mark 4 transponder with Extended Interface Functions (EIF) intended primarily for airline use. It describes the desired operational capabilities and defines standards which are necessary to achieve interchangeability.

This characteristic provides standards for:

Form factor

Control features

Connector pin allocation

Interwiring

Interfaces

These provisions will promote interchangeability of equipment from different manufacturers. The minimum operational and performance capabilities of this unit are further described in the related RTCA and EUROCAE Minimum Operational Performance Standards (MOPS) documents for the Mode S transponder and the Airborne Data Link Processor (refer to Section 3.1 for additional document references).

COMMENTARY

This characteristic, as a minimum, describes an ICAO level 2 transponder. This is the minimum ICAO transponder level needed to comply with European requirements for Mode S Elementary Surveillance. Provisions for Mode S Enhanced Surveillance are provided as an option. Provisions for ADS-B have also been included to the extent that RTCA standards for ADS-B were available at the time of publication of this document.