eATM Portal

ATC21 — Composite surveillance (ADS-B/WAM)

This implementation objective is addressing a surveillance system that exploits the similarities between the two surveillance techniques (ADS-B and WAM) and combines them into a single system. The term composite is used to signify that various system components and data items are shared whilst ensuring that the required degree of channel autonomy/independence is retained. ADS-B information received by WAM system is evaluated and if matching with WAM information extracted by others methods, then it´s used in the WAM output. Information is then periodically re-evaluated.

The exploitation of synergies between the two surveillance techniques into a “composite surveillance system” supports a number of benefits and performance enhancements, compared with the use of 2 separated systems, WAM and ADS-B. These include:

• cost savings, achieved through the co-mounting of system components into a single unit and the associated savings in terms of site costs, communications and efficient utilization of certain common components
• Use of ADS-B message information to support passive acquisition of an aircraft, reducing the 1030/1090 MHz footprint of a WAM surveillance system, especially a reduction in the number of 1030 MHz interrogations.
• cost effective security mitigation techniques, based on the use of additional ‘raw’ RF and timing data (not available in other components of a surveillance infrastructure), which can be used to derive additional indicators, such as Ground based ‘confidence/credibility’ measure enabling e.g. the early identification of anomalous avionic behaviour, or spoofed ‘ADS-B transmissions’.
• Means for performance monitoring and alerting of faults in the system, by supplementing the WAM channels BITE with the comparison between the ADS-B position and WAM channel data as a way to detect failure conditions.
• Improvement of the performance of the ADS-B channel, e.g. by enabling the allowance of temporary reductions in ADS-B quality indicator values, by resolving ADS-B data-to-track association issues related to non-unique 24-bit addresses, by reducing the effects on the resulting along-track horizontal position error.

NOTE 1: The aircraft systems are assumed compliant with the EU Regulation 1207/2011 (Surveillance Performance and Interoperability Implementing Rule - SPI IR) as amended..

NOTE 2: This objective should be seen as a possible mean of compliance with the applicable Regulations. It is without prejudice to the choice of the ANSPs to deploy the most appropriate surveillance solution taking into account the local conditions.

NOTE FOR MILITARY AUTHORITIES: It is the responsibility of each military authority to review this Objective IN ITS ENTIRETY and address each of the SLoAs that the military authority considers RELEVANT for itself. This has to be done on top and above of the review of "MIL" SLoAs which identify actions EXCLUSIVE to military authorities.

Regulator / Air Navigation Service Provider


Applicability Area(s) and Timescales

Applicability Area:
All ECAC+ States
(Subject to local needs)
Timescales From By Applicable to
IOC used for Analytics functioning only - not for implementation planning 15-09-2020 Applicability Area
FOC used for Analytics functioning only - not for implementation planning 31-12-2030 Applicability Area

Links to SESAR Solutions

Links to PCP ATM Sub-Functionalities

ICAO Block Modules: No associated data


Applicable legislation
Regulation (EU) No 2020/587 amending Regulation (EU) No 1207/2011 (SPI)
Applicable ICAO Annexes and other references
Deployment Programme 2022
Operating Environments

Expected Performance Benefits

Operational efficiency
Cost efficiency
System provides two surveillance layers sharing HW components, with the associated cost reduction.
Increases security of ADS-B surveillance layer by verification of received information.
  Code Title From By Related Enablers
REG01 Mandate the airborne carriage and operation of suitable equipment (ADS-B transponders)
  • 15-09-2020
  • 01-01-2030
ASP01 Deploy composite surveillance ADS-B/WAM systems
  • 15-09-2020
  • 01-01-2030
ASP02 Develop a local safety assessment
  • 15-09-2020
  • 01-01-2030
Code Dates
1999 99
2000 00
2001 01
2002 02
2003 03
2004 04
2005 05
2006 06
2007 07
2008 08
2009 09
2010 10
2011 11
2012 12
2013 13
2014 14
2015 15
2016 16
2017 17
2018 18
2019 19
2020 20
2021 21
2022 22
2023 23
2024 24
2025 25

Supporting Material

Title Related SLoAs

EASA - CS ACNS - Certification Specifications for Airborne Communications Navigation and Surveillance - Issue 3 / 05/2021


EC - COMMISSION IMPLEMENTING REGULATION (EU) 2017/373 - (OJ L 62, 8.03.2017, p. 1) - COMMISSION IMPLEMENTING REGULATION (EU) 2017/373 of 1 March 2017 laying down common requirements for providers of air traffic management/air navigation services and other air traffic management network functions and their oversight, repealing Regulation (EC) No 482/2008, Implementing Regulations (EU) No 1034/2011, (EU) No 1035/2011 and (EU) 2016/1377 and amending Regulation (EU) No 677/2011 10/2011


EUROCAE - ED-129B - EUROCAE Technical Specifications for ADS-B Ground system (ED-129B)


EUROCAE - ED-142A - EUROCAE Technical Specification for Wide Area Multilateration (WAM) systems (ED142A)



EUROCONTROL - Air Navigation Systems Safety Assessment Methodology (SAM) - Version 2.1 / 11/2006


ICAO - Doc 9871 - Technical Provisions for Mode S Services and Extended Squitter - Advanced Edition / 04/2012


SJU - SESAR Solution 114: Data Pack for Composite surveillance (ADS-B/WAM) Data Pack

ASP01, ASP02

Consultation & Approval

Working Arrangement in charge
Outline description approved in
Latest objective review at expert level
Commitment Decision Body
Provisional Council (PC)
Objective approved/endorsed in
Latest change to objective approved/endorsed in