GUILDANCE MATERIAL ON GENERATION, PROCESSING

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• 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
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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
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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
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Evolution of ASTERIX Cat 21

• Asterix standard has been developed over many
  years
• Undergone continuous revisions to incorporate the
  latest ADS-B link technology

November 2003
August 2008
May 2011
August 2005
16th APANPIRG adopted Version 0.23 as baselined
version for APAC
Version 2.1 (incorporated DO260B standard)
Version 1.0 (incorporated DO260A standard)
Version 0.23 (Incorporated DO260 standard)
Civil Aviation Department Hong Kong, China
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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
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Choice of ASTERIX Version Number

• Most of the special DO260A and DO260B data items
  cannot be reconstructed from a V0.23 data stream

X
(V2.1 as representation of ASTERIX CAT 21 Version
after V0.23)

• Nearly all V0.23 data items can be reconstructed
  from a received V2.1 data stream

Civil Aviation Department Hong Kong, China
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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
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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
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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
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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
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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
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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
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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 Items Description V0.23 V2.1 Remarks
I021/010 Data Source Identification X X Identifies source of data. Important if validity checks are performed as an anti spoofing capability
I021/030 Time of Day X Data 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 Data received with a Time of Day too far in the past should be discarded
Civil Aviation Department Hong Kong, China
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Generation of ASTERIX at an ADS-B Ground Station
Group 1 (Mandatory)
Data Items Description V0.23 V2.1 Remarks
I021/040 Target Report Descriptor X X Indicates 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.
I021/080 Target Address X X Included in all 1090ES downlink messages, so always available. Used for report/report linkage in ATC tracking.
I021/090 Figure of Merit/Quality Indicators X X Position cannot be used without quality indicator
I021/130 Position in WGS-84 co-ordinates X X Report cannot be used without position
Civil Aviation Department Hong Kong, China
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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 Items Description V0.23 V2.1 Remarks
I021/008 Aircraft operational Status X TCAS capability, Target state reporting capability, CDTI capability, Single/dual aircraft antenna
I021/020 Emitter Category X X Aircraft or vehicle type
I021/140 Geometric Altitude/Height X X Useful for RVSM monitoring
I021/145 Flight Level X X Flight level is an important information to ATC
Civil Aviation Department Hong Kong, China
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Generation of ASTERIX at an ADS-B Ground Station
Group 2 (Operationally Desirable)
Data Items Description V0.23 V2.1 Remarks
I021/155 Barometric Vertical Rate X X Used for predictive tools and safety nets.
I021/157 Geometric Vertical Rate X X Used for predictive tools and safety nets.
I021/160 Ground Vector X X Provides excellent vector to support extrapolation of positional data to time of display
I021/170 Target Identification X X This is the callsign/Flight ID is extremely useful for ATC and matching to the flight plan (if any)
I021/200 Target Status X X This is the emergency type and is highly desirable
Civil Aviation Department Hong Kong, China
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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
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Processing of ASTERIX ADS-B Data at ATC System

• 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

Civil Aviation Department Hong Kong, China
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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
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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
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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
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ATM Automation System Asterix CAT 21 Version YA
ADS-B Ground Station Asterix CAT 21 Version XA
ANSP A
Ver XA
Ver YA

• ADS-B Format Conversion Filter System
• Asterix Format Converter Domestic Ver XA /
  Ver YA Foreign Ver XA / Ver YB
• Pass only data that meet sharing criteria
• Security features

Agreed sharing format
Ver YA
Ver YB

• ADS-B Format Conversion Filter System
• Asterix Format converter Domestic Ver XB /
  Ver YB Foreign Ver XB / Ver YA
• Pass only data that meet sharing criteria
• Security features

Ver YB
Ver XB
ATM Automation System Asterix CAT 21 Version YB
ADS-B Ground Station Asterix CAT 21 Version XB
ANSP B
Domestic Data
Foreign Data
Civil Aviation Department Hong Kong, China
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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 FCF) 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
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• Thank you

Civil Aviation Department Hong Kong, China