The EUROCONTROL Surveillance Data Distribution System (SDDS) is a versatile, high-performance communications gateway that provides value-added services for the safe and secure distribution of Surveillance information in (but not limited to) EUROCONTROL’s All purpose structured surveillance Information exchange (ASTERIX) format.

SDDS enables air navigation service providers (ANSPs) to exchange surveillance data, in an efficient manner, contributing to the reliable and efficient operation of the pan-European ATM network.

SDDS is the cornerstone of the Benelux part of the European Surveillance Network (SURNET) comprising:

4 countries

Belgium, Nederland, Luxembourg, Germany

7 partners

SKEYES, Belgian Air Force, LVNL, Royal Nederland Air Force, ANA-LUX, EUROCONTROL MUAC and DFS

SDDS is meant  to protect ATC systems from deficient data from upstream systems that may harm it, SDDS:

  • checks surveillance data for syntactic and semantic errors (andatory Checks at ASTERIX level);
  • provides firewall services;
  • is able to filter out data that may cause processing problems (Duplications of messages, ADS-B server, BDS-Swap, Overload);



Target reports / sec



25 ms

Average delays ( 95% cases)

1.2 mln

Target reports / sec




Core building blocks system


Users interested in use SDDS today will be able to get:

  • Version 06.01 today - this public version was released on 3 May 2021;
  • Version 06.02 soon - this version is expected to be released in Q2 2022.


SDDS enhances safety, security and interoperability by providing the following features:

Open configuration options


Safety-related features include a high availability hardware platform, alternative data path selection, syntax and range checking, static and dynamic filtering.

Open configuration options


Security-related features begin with a top-level architecture that separates payload and management information, as well as separation between the inter-centre and intra-centre communications.

Open configuration options


Gateway functions allow the simultaneous use of a wide variety of communication protocols. These gateway functions are not restricted to surveillance data. The SDDS can be used in 'transparent mode' for practically any type of information. An automatic switchover function ensures data availability in case of loss of a data source by activating the connection to a substitute.

Open configuration options

ASTERIX data format conversion

ASTERIX data format conversion is an interoperability feature makes it possible for technologies (e.g. ADS-B, Multilateration) to be introduced, without having to update end systems at the same time.

Open configuration options


The static filtering capabilities allow data streams to be tailored to user's needs by applying a wide range of filtering options (e.g. geographical filter, primary/secondary, specific SSR code ranges), while dynamic filtering helps prevent uncontrolled loss of data due to overload. The SDDS uses a lean publish/subscribe mechanism to manage the connections to the provided services, thereby facilitating interoperability and reduce configuration effort. This publish/subscribe mechanism also ensures that users can only access data for which they are authorised.

Open configuration options

ADS-B server

SDDS proposes two modes: data driven and periodic modes to process ADS-B reports from multiple sensors.


Efficient exchange of surveillance data

Surveillance products are constantly evolving: they have to demonstrate innovation and adaptability while meeting the safety and quality requirements of operational systems. When we were first discussing replacing the suRveillance Message Conversion and Distribution Equipment (RMCDE), we asked ourselves whether a value-added network node was still necessary, while introducing an IP-based network infrastructure.

Starting point of a platform-based architecture

It is a general misconception that an IP network infrastructure can cover all communication needs. But, just like the Internet, specific systems that handle content are still needed. On the other hand, the common use of Internet Protocols makes for an open invitation to re-use components wherever possible. This is the starting point for a platform-based architecture.

With the platform-based architecture of the Surveillance Data Distribution System (SDDS), it is possible to re-use a significant portion of the implementation used for other types of message-based service networks (such as air-ground datalinks, meteorological data and even the AMHS - ATM Message Handling System). All that is needed is the development of a domain-specific plug-in. Essential characteristics are cost efficiency through platform- based development, compatibility with international programmes through the use of standard protocols and agreed technologies with a strong focus on security aspects.

SDDS applications

Inter-centre distribution

SDDS was primarily developed for inter-centre communications. In each of the centres in a "network", an SDDS - or similar system - collects local surveillance data (from sensors or surveillance data processing systems) and distributes it to neighbouring centres.

Intra-centre distribution

Another application is the distribution of surveillance data within a centre. The filter and protocol conversion capabilities allow data streams to be tailored for different user groups (Area Control, Approach and Tower, but also data processing systems with different needs).

International gateway

A more generic application would be as a general-purpose international gateway. The SDDS allows different protocol types to be connected. Its advanced security features ensure that data crossing borders is subject to high levels of control.

Safety compliance and certification

SDDS complies with Software Assurance Level 3 (SWAL 3) and SIMOS-related activities follow SWAL3 processes. SIMOS processes are compliant with ISO 9001. Since 2020, EUROCONTROL has been issuing an EC Declaration of Suitability for Use for all new SDDS systems:

Support and maintenance

Support and maintenance is managed by the EUROCONTROL SDDS Implementation and Operational Support Team (SIMOS). SIMOS provides direct support to the users, such as SDDS-related incident and problem management, training and the further evolution of the SDDS. In turn, the EUROCONTROL team is supported by an industrial partner which is specifically responsible for documentation and software maintenance and the implementation of new functions.

SIMOS in in charge of:

  • support activities at a European level to the numerous EMSO SDDS systems (both Operational and Pre-Operational);
  • maintenance and preparation of the SDDS Courses held at EUROCONTROL IANS (Luxemburg) to train SDDS Users;
  • verification, avoiding any regression, and the release of bug fixes, updates and new SDDS versions.


  • Provides a Helpdesk service, by answering SDDS Support Requests (SRs) raised by SDDS users, normally for EMSO ANSP representatives.
  • Processes SDDS Trouble Reports (TRs) and SDDS Change Proposals (CPs), including reproducing TRs on SIMOS reference platforms and discussing technical matters with Users, Industrial Partners and Subcontractors.
  • Manages the developments performed by Subcontractors. Produces and publishes SDDS technical documentation (via iSIMOS tool).
  • Participates in factory acceptance testing.
  • Tests and distributes patches and new SDDS versions delivered by Industrial Partners to SDDS Users (via iSIMOS tool).

The SIMOS Team delivers, on average, per year:

  • 40 solutions for SDDS Support Requests (SR);
  • 20 fixes for SDDS Trouble Report (TR);
  • 7 enhancements for SDDS Change Proposal (CP).

The SIMOS service does not include hardware support.


SDDS and SIMOS can be accessed by:

  • evalutaors, upon of signature of the SDDS EVALUATION licence (does not include the SIMOS support);
  • SDDS users within EUROCONTROL Member States organisations (EMSO), including organisations that have signed a Comprehensive Agreements, upon of signature of SDDS Service Level Agreement (includes the SIMOS support);
  • SDDS distributors for non-EUROCONTROL Member States organisations (NEMSO), upon of signature of the SDDS Distributor License Agreement (does not include the SIMOS support).


The SDDS software (in binary form, no source code) and the SIMOS service are currently free of charge to EMSO that have signed the SDDS SLA.

The SDDS software (in binary form, no source code) is also available to SDDS distributors for NEMSO, upon signature of a Distributor License Agreement (DLA) and fees as described in the DLA (no SIMOS service is available in this case).

The SDDS software (in binary form, no source code) is also available for evaluation purposes to interested parties upon signature of an evaluation license, which is limited in time but free of charge (no SIMOS service is available in this case).

Interested in a SDDS licence?

Send us your request via our contact form. 

Communication channels

The main channels of communication with the SIMOS team are done via the tools listed below. SDDS users can find a complete introduction to the working arrangements and the means of communication with the SIMOS team in the 'SIMOS Working Arrangements' document.

Learn more on our dedicated pages


Anomaly reporting tool for surveillance avionics


Surveillance Data Distribution System Dashboard


Surveillance Data Distribution System and Dashboard Library

Training and support materials

We offer SDDS introductory and advanced courses at our Institute for Air Navigation Services in Luxembourg.

The following policy applies to SDDS Courses and their material:

  • SUR-SDDS-INTRO free of charge for EMSO ANSPs;
  • SUR-SDDS-ADVANCED free of charge for EMSO ANSPs;
  • The Course material is available upon signature of a Non-Disclosure Agreement to EMSO ANSPs (free of charge);
  • The Course material is available to SDDS Distributors too.

Interested in a SDDS training?

Send us your request via our contact form. 


All changes in SDDS are done under control of the Change Control Board (CCB) of the SDDS User Group (SDDS-UG).

In the context of SIMOS, EUROCONTROL acts as the SDDS-UG representative and provides guidance to the industrial partners on their behalf.

The activities of maintenance and support are currently performed by EUROCONTROL, whereby our experts in conjunction with industrial partners ensure support to the SDDS community.

SDDS manager is responsible for the overall strategy of SDDS, in terms of the contractual actions, procurement, licencing and SDDS User Group among others.


Surveillance Data Distribution System Dashboard


Surveillance Data Distribution System and Dashboard Library


Anomaly reporting tool for surveillance avionics


SIMOS Working Arrangements