asterix 018 "Mode S Datalink Function Messages" edition 1.8 date 2024-05-14 preamble Surveillance data exchange. items 000 "Message Type" definition Allows identification of the message type. element 8 table 0: Associate_req 1: Associate_resp 2: Release_req 3: Release_resp 4: Abort_req 5: Keep_alive 16: Aircraft_report 17: Aircraft_command 18: II_code_change 32: Uplink_packet 33: Cancel_uplink_packet 34: Uplink_packet_ack 35: Downlink_packet 38: Data_XON 39: Data_XOFF 48: Uplink_broadcast 49: Cancel_uplink_broadcast 50: Uplink_broadcast_ack 52: Downlink_broadcast 64: GICB_extraction 65: Cancel_GICB_extraction 66: GICB_extraction_ack 67: GICB_response 001 "Result" definition Indicates the status of a particular message together with additional information. group CAUSE "Cause" element 4 table 0: Accepted, the request is accepted and is under processing 1: Rejected, the request has not been accepted 2: Cancelled, the request has been cancelled 3: Finished, the request has been accepted and successfully processed 4: Delayed, the request processing is temporarily delayed but the request is still valid 5: In Progress, the request is being successfully processed 6: In Progress, the request is being successfully processed DIAG "Diagnostic" element 4 table 0: No diagnostic available 1: Aircraft Exit 2: Incorrect aircraft address 3: Impossibility to process the message 4: Insufficient or change in data link capability 5: Invalid LV field 6: Duplicate request number 7: Unknown request number 8: Timer T3 expiry 9: Expiry of I/R delivery timer 10: Uplink flow disabled by UC 002 "Time of Day" definition Absolute time stamping expressed as Co-ordinated Universal Time (UTC) time. element 24 unsigned quantity 1/2^7 "s" remark Notes: 1. The time of day value is reset to zero each day at midnight. 2. For time management in radar transmission applications, refer to Part 1, paragraph 5.4. 004 "II Code" definition Indicates the interrogator’s current and previous II Code. group PREVIOUSII "Former II Code" element 4 raw CURRENTII "Current II Code" element 4 raw remark Note: - The Previous II code shall be set to the Current II code value when there is no Previous II code available. 005 "Mode S Address" definition Technical Mode S address used for identification of an aircraft, as defined in ICAO Annex 10. element 24 raw 006 "Mode S Address List" definition List of technical Mode S addresses. repetitive 1 element 24 raw 007 "Aircraft Data Link Command" definition Command for the aircraft data link communications. It allows the GDLP to enable or disable the uplink & downlink data flows for a specified aircraft. group UM "Uplink Mask" element 1 table 0: UC shall be ignored 1: UC shall be taken into account DM "Downlink Mask" element 1 table 0: DC shall be ignored 1: DC shall be taken into account UC "Uplink Command" element 1 table 0: the uplink flow shall be enabled 1: the uplink flow shall be stopped DC "Downlink Command" element 1 table 0: the downlink flow shall be enabled 1: the downlink flow shall be stopped spare 4 remark Note: - This command applies to the interrogator's Current status (UCS/DCS) and does not affect the interrogator’s Default Status (see UDS/DDS in Data Item I018/008). 008 "Aircraft Data Link Status" definition Status for the aircraft data link communications. extended UDS "Uplink Default Status" element 1 table 0: The interrogator is enabled to uplink frames 1: The interrogator is disabled to uplink frames DDS "Downlink Default Status" element 1 table 0: The interrogator is enabled to extract frames 1: The interrogator is disabled to extract frames UCS "Uplink Current Status" element 1 table 0: The interrogator is enabled to uplink frames 1: The interrogator is disabled to uplink frames DCS "Downlink Current Status" element 1 table 0: The interrogator is enabled to extract frames 1: The interrogator is disabled to extract frames spare 2 EI "Exit Indication" element 1 table 0: The aircraft is in the Datalink coverage map of the interrogator 1: The aircraft is not in the Datalink coverage map of the interrogator - IC "Interrogator Control" element 1 table 0: The interrogators current ability to uplink/downlink frames (UCS/DCS) and the content of the Aircraft_report could be changed using D_Data_link_command 1: The interrogators current ability to uplink/downlink frames (UCS/DCS) and the content of the Aircraft_report cannot be changed using D_Data_link_command spare 6 - remark Notes: 1. The current status should never be more restrictive than the default status. 2. IC is usually set 1when the interrogator is a member of a cluster with a decentralised data link responsibility protocol. IC is usually set to 0 when the interrogator is connected to a GDLP. IC settings shall comply with the rules defined in Ref.3. 009 "Aircraft Data Link Report Request" definition Request for an Aircraft_report message. extended SR "" element 1 table 0: The next Aircraft_report may not include D_Data_link_status 1: The next Aircraft_report shall include D_Data_link_status AR "" element 1 table 0: The next Aircraft_report may not include D_COM 1: The next Aircraft_report shall include D_COM ER "" element 1 table 0: The next Aircraft_report may not include D_ECA 1: The next Aircraft_report shall include D_ECA FR "" element 1 table 0: The next Aircraft_report may not include D_CQF 1: The next Aircraft_report shall include D_CQF MR "" element 1 table 0: The next Aircraft_report may not include D_CQF_method 1: The next Aircraft_report shall include D_CQF_method PR "" element 1 table 0: The next Aircraft_report may not include D_Polar_position 1: The next Aircraft_report shall include D_Polar_position CR "" element 1 table 0: The next Aircraft_report may not include D_Cartesian_position 1: The next Aircraft_report shall include D_Cartesian_position - ID "" element 1 table 0: The next Aircraft_report may not include Aircraft_ID 1: The next Aircraft_report shall include Aircraft_ID MA "" element 1 table 0: The next Aircraft_report may not include Mode_A 1: The next Aircraft_report shall include Mode_A SP "" element 1 table 0: The next Aircraft_report may not include Speed 1: The next Aircraft_report shall include Speed HG "" element 1 table 0: The next Aircraft_report may not include Height 1: The next Aircraft_report shall include Height HD "" element 1 table 0: The next Aircraft_report may not include Heading 1: The next Aircraft_report shall include Heading spare 2 - remark Note: - This item indicates to the DLF which items to send in the next Aircraft_report messages (for a specified aircraft) through the use of flags. These flags concern D_Data_link_status, D_COM, D_ECA, D_CQF, D_CQF_method, D_Polar_position, D_Cartesian_position, D_Aircraft_ID, D_Mode_A, D_Speed, D_Height, D_Heading. 010 "Transponder Communications Capability" definition Transponder Communications Capability group spare 5 COM "Communications Capability of the Transponder" element 3 table 0: No communications capability (surveillance only) 1: Comm. A and Comm. B capability 2: Comm. A, Comm. B and Uplink ELM 3: Comm. A, Comm. B and Uplink ELM and Downlink ELM 4: Level 5 Transponder capability 011 "Capability Report" definition Capability report as described in the Mode S subnetwork SARPs element 56 raw 012 "Aircraft Coverage Quality Factor" definition Coverage Quality Factor (CQF) of an aircraft (for a given interrogator). group FS "Flight Status" element 1 table 0: Aircraft is airborne 1: Aircraft is on the ground CQF "Aircraft CQF" element 7 table 0: The CQF calculation method is not supported 1: The CQF is minimum 126: The CQF is maximum 127: The CQF is undefined according to the calculation method 013 "Aircraft CQF Calculation Method" definition Indicates which criteria to take into account when computing the CQF of an aircraft for an interrogator. element 8 raw 014 "Aircraft Position in Polar Co-ordinates" definition Measured position of an aircraft in local polar co-ordinates. group RHO "" element 16 unsigned quantity 1/2^8 "NM" < 256 THETA "" element 16 unsigned quantity 360/2^16 "°" remark Note: - When expressed in 16 bits, signed or unsigned azimuths have the same value. 015 "Aircraft Position in Cartesian Co-ordinates" definition Calculated position of an aircraft in Cartesian co-ordinates. group X "X-Component" element 16 signed quantity 1/2^7 "NM" >= -256 <= 256 Y "Y-Component" element 16 signed quantity 1/2^7 "NM" >= -256 <= 256 remark Note: - Negative values are expressed in 2’s complement form, bit-32 and bit-16 shall be set to 0 for positive values and 1 for negative values. 016 "Packet Number" definition Number used to correlate an uplink packet request and its associated acknowledgement. element 32 unsigned integer 017 "Packet Number List" definition List of numbers used to correlate an uplink packet request and their associated acknowledgements repetitive 1 element 32 unsigned integer 018 "Mode S Packet Properties" definition Properties of an uplink Mode S packet, i.e. its internal priority and its capability to be multiplexed or not, and its type (SVC, MSP or ROUTE). group spare 1 PR "Mode S Packet Internal Priority" element 5 unsigned integer PT "Packet Type" element 2 table 0: SVC packets 1: MSP packets 2: Route packets remark Note: - The PT field is used to identify the ROUTE packets which have a higher priority than SVCs. The PR field is used to describe the priority of SVCs as follows: 0 = low 1 = high For ROUTE and MSP packets the value of PR has no significance. However, for the purpose of standardisation, it is recommended that for ROUTE packets, PR is set to 15 and for MSPs the PR should be set to 31. 019 "Mode S Packet" definition A Mode S packet as defined in the Mode S subnetwork SARPs. explicit 020 "Broadcast Number" definition Number used to correlate an uplink broadcast request and its associated acknowledgement. element 32 unsigned integer 021 "Broadcast Properties" definition Properties of an uplink broadcast request (power, duration, coverage). group PRIORITY "Priority" element 4 unsigned integer POWER "Power" element 4 unsigned integer DURATION "Duration" element 8 unsigned quantity 1 "s" COVERAGE "Coverage" element 32 raw remark Notes: 1. A broadcast with a higher priority will temporarily delay a lower priority broadcast if necessary. The delayed broadcast will be resumed as soon as possible for its remaining time. 2. The sectors are numbered from 1 to 32 clockwise, sector 1 being the first sector after the North. 022 "Broadcast Prefix" definition Contents of the 32 first bits of an uplink broadcast interrogation. group spare 5 PREFIX "Prefix Field" element 27 raw remark Note: - The Mode S uplink broadcast interrogation will be made up of this D_Broadcast_prefix field followed by the D_Broadcast field and then by the Address/Parity field (in this order), as defined in ICAO Annex 10. In the interrogator, the 5 first bits of D_Broadcast_prefix will be replaced by ICAO UF field, as defined in Annex 10. 023 "Uplink or Downlink Broadcast" definition Broadcast message sent (MA field of the Comm-A frame) or received (MB field of the Comm-B frame), conformant with the ICAO Manual on Mode S Specific Services. element 56 raw 025 "GICB Number" definition Number used to correlate subsequent GICB messages (i.e. responses and acknowledgements) with the original GICB request. element 32 unsigned integer 027 "BDS Code" definition BDS code of the GICB to be extracted. element 8 raw 028 "GICB Extraction Periodicity" definition Periodicity of the GICB extractions. element 16 unsigned quantity 1 "s" 029 "GICB Extracted" definition GICB extracted message (MB field of the Comm-B frame). i.e., the contents of a BDS register, conformant with the ICAO Manual on Mode S Specific Services. element 56 bds ? 030 "GICB Properties" definition Properties of the GICB extractions. group PRIORITY "GICB Priority" element 5 unsigned integer spare 3 PC "Periodicity Constraint" element 1 table 0: The periodicity may not be strictly respected 1: The periodicity shall be strictly respected AU "Asynchronous Update" element 1 table 0: GICB extractions should be sent only when required by the periodicity 1: If a GICB extraction is done due to external conditions, an update will also be sent, even if it does not match the expected periodicity NE "Non Extraction" element 1 table 0: The GICB extraction is attempted according to the periodicity 1: There will no GICB attempts RD "Reply Destination" element 2 table 0: The extracted GICB must be sent only on the Data Link line 1: The extracted GICB must be sent only on the Surveillance line 2: The extracted GICB must be sent both on the Data Link and on the Surveillance lines spare 3 remark Note: - The Non Extraction flag (NE) should be used only if the Asynchronous Update flag (AU) is set to true. It is specially reserved to the ACAS' RA extraction (asynchronous update without periodic extraction request). 031 "Aircraft Identity" definition Identity of the aircraft extracted by a BDS 20 as described in ICAO Annex 10. element 48 raw 032 "Aircraft Mode A" definition Mode-3/A code converted into octal representation. group V "" element 1 table 0: Code validated 1: Code not validated G "" element 1 table 0: Default 1: Garbled code L "" element 1 table 0: Mode-3/A code derived from the reply of the transponder 1: Mode-3/A code not extracted during the last scan spare 1 MOD3A "" element 12 string octal remark Note: - Bit 15 has no meaning in the case of a smoothed Mode-3/A code and is set to 0 for a calculated track. For Mode S, it is set to one when an error correction has been attempted. 033 "Aircraft Height" definition Flight Level converted into binary representation. group V "" element 1 table 0: Code validated 1: Code not validated G "" element 1 table 0: Default 1: Garbled code FL "Flight Level" element 14 signed quantity 1/2^2 "FL" remark Notes: 1. The value shall be within the range described by ICAO Annex 10 2. For Mode S, bit 15 (G) is set to one when an error correction has been attempted. 3. If Altitude is not extracted on the last scan, it is an implementation issue as to whether Altitude is output from track file, if at all. 034 "Aircraft Speed" definition Tracker calculated Ground Speed of an aircraft. element 16 unsigned quantity 1/2^14 "NM/s" 035 "Aircraft Heading" definition Tracker calculated heading of an aircraft. . The heading is the heading with respect to the geographical north at the aircraft position. element 16 unsigned quantity 360/2^16 "°" 036 "Data Source Identifier" definition Identification of the source node for the GDLP/LU data group SAC "System Area Code" element 8 raw SIC "System Identification Code" element 8 raw remark Note: - The up-to-date list of SACs is published on the EUROCONTROL Web Site (http://www.eurocontrol.int/asterix). 037 "Data Destination Identifier" definition Identification of the destination node for the GDLP/LU data. group SAC "System Area Code" element 8 raw SIC "System Identification Code" element 8 raw remark Note: - The up-to-date list of SACs is published on the EUROCONTROL Web Site (http://www.eurocontrol.int/asterix). uap 036 037 000 001 005 016 017 018 019 028 030 025 027 029 002 006 007 008 009 010 011 014 015 020 021 022 023 004 031 032 033 034 035 012 013