1. GUILDANCE MATERIAL ON GENERATION, PROCESSING & SHARING OF ASTERIX CATEGORY 21 ADS-B MESSAGES Jointly Presented by Australia and Hong Kong, China ADS-B SITF/11 April 2012 Civil Aviation Department Hong Kong, China

2. Introduction “All Purpose Structured Eurocontrol Surveillance Information Exchange” (ASTERIX) Category 21 –A data format standard globally accepted by the Air Traffic Management (ATM) system manufacturing industry for sharing of ADS-B data with ATM automation systems –Used to convey ADS-B data from ADS-B ground stations to ATC processing and display system Civil Aviation Department Hong Kong, China

3. ASTERIX Cat 21 in Asia Pacific (APAC) Regions During the 16th APANPIRG Meeting held in August 2005 –ASTERIX Category 21 version 0.23 which has incorporated DO260 standard was adopted as the baselined ADS-B data format for deployment of ADS-B ground stations sharing of ADS-B data in the APAC Regions –DO260A and DO260B standards have yet been fully defined during that period Civil Aviation Department Hong Kong, China

4. Evolution of ASTERIX Cat 21 Civil Aviation Department Hong Kong, China November 2003 August 2008 May 2011 Version 0.23 (Incorporated DO260 standard) Version 1.0 (incorporated DO260A standard) Version 2.1 (incorporated DO260B standard) August 2005 16th APANPIRG adopted Version 0.23 as baselined version for APAC Asterix standard has been developed over many years Undergone continuous revisions to incorporate the latest ADS-B link technology

5. Choice of ASTERIX Version Number Asia Pacific decided to use V0.23 as the version for sharing ADS-B data between States in 2005 V0.23 –Provides adequate information for ATC operational services –Can be used with DO260, DO260A and DO260B ADS-B avionics/ground stations to provide ATC operational services –Cannot fully support all enhanced capabilities offered by DO260A and DO260B Civil Aviation Department Hong Kong, China

6. Choice of ASTERIX Version Number Civil Aviation Department Hong Kong, China V2.1V0.23 Nearly all V0.23 data items can be reconstructed from a received V2.1 data stream Most of the special DO260A and DO260B data items cannot be reconstructed from a V0.23 data stream (V2.1 as representation of ASTERIX CAT 21 Version after V0.23)

7. Support of DO260A/B using ASTERIX Cat 21 V0.23 V0.23 does not directly support DO260A/B Ground station software can generate useful V0.23 Asterix data from DO260A/B reports using some techniques (e.g. generation of NUC value based on pre- defined table on combination of SIL, NIC and NAC) A more recent version of Cat 21 is needed if there is a particular need for the ATC system to access to NIC/NAC or SIL or other data items that exist in DO260A/B States are encouraged to review and determine additional DO260A/B fields beneficial to warrant adoption of newer versions of Asterix Cat 21 Civil Aviation Department Hong Kong, China

8. Specification of ASTERIX Message Processing ASTERIX Cat 21 specification: –Defines characteristics of data on the interface including items as optional and mandatory on the interface –It does NOT specify the behaviour of the transmitting ground station nor behaviour of the receiving ATM automation system Civil Aviation Department Hong Kong, China

9. Specification of ASTERIX Message Processing ADS-B ground station specification: –Defines the Asterix standard to be adopted for outputting data and which optional Asterix data items are required to be delivered on the Asterix interface –indicates how the ground station processes and outputs every received DO260, DO260A and DO260B data element into an Asterix data element/field –indicates which and how each Asterix data element and field presented at the output are populated Civil Aviation Department Hong Kong, China

10. Specification of ASTERIX Message Processing ATM automation system specification: –Defines which received Asterix data element and fields are processed and how they are processed –Defines which Asterix optional data fields are required by the ATM automation system Civil Aviation Department Hong Kong, China

11. Specification of ASTERIX Message Processing ANSPs that specify ADS-B ground stations and ATM automation systems to consider carefully what they need to achieve Specification which simply require compliance with a particular ASTERIX standard will be inadequate in most circumstances Civil Aviation Department Hong Kong, China

12. Specification of ASTERIX Message Processing ANSPs together with suppliers should: –Specify the Asterix standard version to be used Defines the message formats that are placed on the link between ADS-B ground station and ATM automation systems –Specify the ADS-B ground station behaviour When data is received from the aircraft, the ground station is required to fill appropriate optional Asterix data fields –Specify the ATM automation system behaviour and syntax checks applied to the Asterix data, including any triggers for the system to discard data Civil Aviation Department Hong Kong, China

13. Generation of ASTERIX at an ADS-B Ground Station Group 1 (Mandatory) – an Asterix Cat 21 message should not be transmitted unless the mandatory data items defined below are all present: Data ItemsDescriptionV0.23V2.1Remarks I021/010Data Source Identification XXIdentifies source of data. Important if validity checks are performed as an anti spoofing capability I021/030Time of DayXData received with a Time of Day too far in the past should be discarded I021/071 or I021/073 Time of applicability of Position or Time of Message reception for position X Civil Aviation Department Hong Kong, China

14. Generation of ASTERIX at an ADS-B Ground Station Data ItemsDescriptionV0.23V2.1Remarks I021/040Target Report DescriptorXXIndicates if report is a duplicate, on the ground, is a simulated target, is a test target. This needs to be checked by ATC system prior to processing. I021/080Target AddressXXIncluded in all 1090ES downlink messages, so always available. Used for report/report linkage in ATC tracking. I021/090Figure of Merit/Quality Indicators XXPosition cannot be used without quality indicator I021/130Position in WGS-84 co- ordinates XXReport cannot be used without position Civil Aviation Department Hong Kong, China Group 1 (Mandatory)

15. Generation of ASTERIX at an ADS-B Ground Station Group 2 (Operationally Desirable) - should always be transmitted whenever data are received by the ground station from aircraft (if allowed by relevant Asterix standard chosen): Data ItemsDescriptionV0.23V2.1Remarks I021/008Aircraft operational Status XTCAS capability, Target state reporting capability, CDTI capability, Single/dual aircraft antenna I021/020Emitter CategoryXXAircraft or vehicle type I021/140Geometric Altitude/Height XXUseful for RVSM monitoring I021/145Flight LevelXXFlight level is an important information to ATC Civil Aviation Department Hong Kong, China

16. Generation of ASTERIX at an ADS-B Ground Station Data ItemsDescriptionV0.23V2.1Remarks I021/155Barometric Vertical Rate XXUsed for predictive tools and safety nets. I021/157Geometric Vertical Rate XX I021/160Ground VectorXXProvides excellent vector to support extrapolation of positional data to time of display I021/170Target IdentificationXXThis is the callsign/Flight ID is extremely useful for ATC and matching to the flight plan (if any) I021/200Target StatusXXThis is the emergency type and is highly desirable Civil Aviation Department Hong Kong, China Group 2 (Operationally Desirable)

17. Generation of ASTERIX at an ADS-B Ground Station Group 3 (Optional) – remaining data items belong to this Group which may need to be transmitted depending on availability of such data from aircraft and/or other specific operational needs Specification for ADS-B ground station should take into account: –Transmission of all Group 1 (Mandatory) and Group 2 (Operationally Desirable) data items –Whether Group 3 (Optional) data items will be transmitted should be configurable on item-by-item basis depending on specific operational needs and link bandwidth availability Civil Aviation Department Hong Kong, China

18. Processing of ASTERIX ADS-B Data at ATC System Civil Aviation Department Hong Kong, China An Asterix Cat 21 message should not be accepted by the ATC System for processing unless it includes at least all Group 1 data items The ATC system should process all received Asterix Cat 21 message data items that bring operational benefits. The ATC System should appropriately process those Group 2 data items depending on operational need Whether the ATC system will process Group 3 optional data items will depend on specific operational needs

19. Data Sharing of ASTERIX ADS-B Data Data items that should be included in data sharing: –Group 1 (Mandatory) –Group 2 (Operationally Desirable) when such data are received from aircraft Subject to mutual agreement between the two data sharing parties concerned, Group 3 (Optional) data items needs to be shared Civil Aviation Department Hong Kong, China

20. ADS-B Format Conversion and Filter System Evolution of 1090ES ADS-B link technology and avionics standards will continue Asterix standards will continue to evolve ATC systems need to be adaptable and be able to cope with new functionality requirements and new message standards Civil Aviation Department Hong Kong, China

21. ADS-B Format Conversion and Filter System Provides ADS-B format conversion between domestic and foreign ADS-B systems Allows data meeting agreed sharing criteria to be passed through Cost-effective way to provide the necessary protection and flexibility to adapt to new message standards Civil Aviation Department Hong Kong, China

22. ADS-B Ground Station Asterix CAT 21 Version “X A ” ADS-B Format Conversion & Filter System - Asterix Format Converter : Domestic: Ver X A / Ver Y A ; Foreign: Ver X A / Ver Y B - Pass only data that meet sharing criteria - Security features Agreed sharing format ATM Automation System Asterix CAT 21 Version “Y A ” ANSP “A” ADS-B Ground Station Asterix CAT 21 Version “X B ” ATM Automation System Asterix CAT 21 Version “Y B ” Ver “X A ”Ver “Y A ” Ver “Y B ”Ver “X B ” Ver “Y B ” ADS-B Format Conversion & Filter System - Asterix Format converter : Domestic: Ver X B / Ver Y B ; Foreign: Ver X B / Ver Y A - Pass only data that meet sharing criteria - Security features ANSP “B” Domestic Data Foreign Data

23. Conclusion To recognize differences between DO-260, DO260A, DO260B for ADS-B ground stations and Asterix Cat 21 To agree on proposed mandatory, desirable and optional ADS-B data fields for sharing of ADS-B data in Asterix Cat 21 format to ensure system interoperability and harmonize ADS-B implementation in APAC Regions To take note of possibility of deploying ADS-B format conversion & filter (ADS-B FC&F) system in overall design and integration of ATM automation systems and ADS-B ground stations To adopt this “Guidance Material on Generation, Processing and Sharing of Asterix Category 21 ADS-B Messages” for use by APAC States/Administrations Civil Aviation Department Hong Kong, China

24. Thank you Civil Aviation Department Hong Kong, China