FINAL REPORT - Stakeholders - Ofcom

separation minima to be achieved due to the high relative accuracy, integrity and
availability.
Therefore, a mandate for SSR equipage exists throughout European airspace. Indeed, for
safety and redundancy reasons, dual coverage of SSR is required throughout the core
en-route area of Europe. In TMAs, SSR and PSR coverage is required.
Mode S Elementary Surveillance has replaced MSSR in 6 core European States (not
including the UK) since 2002. Mode S Enhanced Surveillance is proposed to be
implemented in France, UK and Germany from 2005 (mandatory equipage of the
commercial fleet), with all aircraft equipped by 2008. The following quote from
EUROCONTROL’s Mode S Programme states the uncertain situation that Mode S
Enhanced Surveillance is in:
“Mode S Elementary Surveillance will be introduced in many ECAC States; its selective
interrogation capability will overcome the limitations on the current SSR systems, allowing
capacity to continue to increase in a safe and efficient manner. The Provisional Council
has approved the implementation of Mode S Elementary Surveillance. Some users are
not convinced about the relevance of Mode S Enhanced Surveillance and therefore have
held up Provisional Council (PC) approval so far.”
The CAA has initiated separate Regulatory Impact Assessments (RIAs) 2 for both the
proposed implementation of Mode S Enhanced Surveillance for IFR GAT flights in
designated TMA and En Route airspace from 31 March 2005 and for the implementation
of Mode S elementary surveillance for flights elsewhere from 31 March 2008. These RIAs
are now at the second stage of consultation.
ACAS also uses SSR signals to track and avoid collision with other transponder equipped
aircraft.
Future systems have also been designed (and are currently being tested in preoperational
trials) to follow-on from Mode S (using the same transponders). 1090
Extended Squitter (a broadcast datalink) will broadcast over the same frequency
(1090MHz), and decisions have been taken in the US and Europe to use this datalink to
introduce airborne surveillance (via ADS-B). As such, Airbus and Boeing are intending to
equip their aircraft to support the broadcast of 1090ES by 2005.
Users (particularly ANSPs) will be required to make decisions on whether to target Mode
S Enhanced Surveillance or 1090ES (or both) in the medium term. Both technologies
deliver aircraft derived data for use in ground tools, and both therefore bring significant
benefits over current systems. However, these benefits will only mature in synch with the
development and implementation of ground tools that will use them. At present, the lack
of tools to use the additional data beneficially is one of the major barriers to any decision
being made by the users. It is understood that NATS is considering an initial
implementation of controller tools which will use Mode S derived data and provide some
airspace capacity benefits.
2 An RIA is a policy tool that assesses the impact, in terms of costs, benefits and risks of
any proposed regulation. It is intended to improve the quality of advice to Ministers and
encourages informed debate. Part of the RIA process is to conduct full public
consultation.
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