European Aviation Safety Agency

Safety Information Bulletin - Honeywell Mode S Transponders: Enhanced Surveillance Parameters Not Provided To Mode S Ground Stations
 N SIB 2016-19

Annotation

Description:

Mode S ground stations are unable to receive Mode S Enhanced Surveillance (EHS) parameters from aeroplanes, fitted with a certain Honeywell transponder, as listed above. The issue is related to the report of airborne capability when interrogated by secondary radars using Mode S protocols with a Surveillance Identifier (SI) code. An incorrect Mode S transponder register content is sent in reply to the Mode S ground station request. The result is that the Mode S ground station cannot correctly establish the EHS capability of the aeroplane and therefore it does not request any EHS parameters.

The Mode S EHS parameters are used by controllers and ground based safety nets. Most European States have already mandated the provision of Mode S EHS parameters through National aeronautical information publications (AIP). Aeroplanes operating in the airspace of these States may be subject to ramp checks to determine compliance with the affected State’s AIP.

These parameters are also required for compliance with European Commission Regulation (EU) 1207/2011, amended by Regulation (EU) 1028/2014, which will extend this provision across the rest of Europe. A transponder software upgrade is required to correct this, and other miscellaneous issues.

At this time, the safety concern described in this SIB is not considered to be an unsafe condition that would warrant Airworthiness Directive (AD) action under Regulation (EU) 748/2012, Part 21.A.3B.

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