Asterix expansion 021 - ADS-B Target Reports Expansion

category: 021

edition: 1.4

date: 2018-03-08

FSPEC byte size: 1

Items

BPS - Barometric Pressure Setting

definition: Barometric Pressure Setting

Group

Spare bits: 4

BPS/BPS - Barometric Pressure Setting

Element

bit size: 12

Unsigned quantity

LSB = 1/10 hPa ≈ 0.1 hPa

unit: "hPa"

>= 0.0

<= 409.5

Notes:

• BPS is the barometric pressure setting of the aircraft minus 800 hPa
• A value of "0" indicates that in the aircraft a value of 800 hPa or less has been selected.
• A value of "409.5" indicates that in the aircraft a value of 1209.5 hPa or more has been selected.

SH - Selected Heading

definition: Selected Heading

Group

Spare bits: 4

SH/HDR - Horizontal Reference Direction

Element

bit size: 1

Values:

0:

True North

1:

Magnetic North

SH/STAT - Selected Heading Status

Element

bit size: 1

Values:

0:

Data is either unavailable or invalid

1:

Data is available and valid

SH/SH - Selected Heading

Element

bit size: 10

Unsigned quantity

LSB = 45/2⁶ ° ≈ 0.703125 °

unit: "°"

On many aircraft, the ADS-B Transmitting Subsystem receives Selected Heading from a Mode Control Panel / Flight Control Unit (MCP / FCU). Users of this data are cautioned that the Selected Heading value transmitted by the ADS-B Transmitting Subsystem does not necessarily reflect the true intention of the airplane during certain flight modes (e.g., during LNAV mode).

NAV - Navigation Mode

definition: Navigation Mode Settings

Group

NAV/AP - Autopilot

Element

bit size: 1

Values:

0:

Autopilot not engaged

1:

Autopilot engaged

NAV/VN - Vertical Navigation

Element

bit size: 1

Values:

0:

Vertical Navigation not active

1:

Vertical Navigation active

NAV/AH - Altitude Hold

Element

bit size: 1

Values:

0:

Altitude Hold not engaged

1:

Altitude Hold engaged

NAV/AM - Approach Mode

Element

bit size: 1

Values:

0:

Approach Mode not active

1:

Approach Mode active

Spare bits: 4

This data-item should only be transmitted if an ADS-B indication has been received that the mode bits have been "actively populated".by the avionics (1090 ES version 2 (as defined in I021/210) BDS 6,2, subtype 1, bit 47: "Status of MCP / FCU Mode Bits")

GAO - GPS Antenna Offset

definition: GPS Antenna Offset

Element

bit size: 8

Raw Content

The value of this field is copied from the respective bits 33-40 of version 2 (as defined in I021/210) of 1090 ES BDS register 6,5 (Aircraft Operational Status)

SGV - Surface Ground Vector

definition: Ground Speed and Track Angle elements of the Surface Ground Vector.

Extended

SGV/STP

Element

bit size: 1

Values:

0:

Aircraft has not stopped

1:

Aircraft has stopped

SGV/HTS

Element

bit size: 1

Values:

0:

Heading/Ground Track data is not valid

1:

Heading/Ground Track data is valid

SGV/HTT

Element

bit size: 1

Values:

0:

Heading data provided

1:

Ground Track provided

SGV/HRD

Element

bit size: 1

Values:

0:

True North

1:

Magnetic North

SGV/GSS - Ground Speed

Element

bit size: 11

Unsigned quantity

LSB = 1/2³ kt ≈ 0.125 kt

unit: "kt"

(FX) - extension bit

SGV/HGT - Heading/Ground Track Information

Element

bit size: 7

Unsigned quantity

LSB = 45/2⁴ ° ≈ 2.8125 °

unit: "°"

(FX) - extension bit

STA - Aircraft Status

definition: This item contains flags to convey information on the status of a target.

Extended

STA/ES

Element

bit size: 1

Values:

0:

Target is not 1090 ES IN capable

1:

Target is 1090 ES IN capable

STA/UAT

Element

bit size: 1

Values:

0:

Target is not UAT IN capable

1:

Target is UAT IN capable

Spare bits: 5

(FX) - extension bit

TNH - True North Heading

definition: True North Heading (Element of Air Vector).

Element

bit size: 16

Unsigned quantity

LSB = 360/2¹⁶ ° ≈ 5.4931640625e − 3 °

unit: "°"

Magnetic Heading is defined in I021/152.

MES - Military Extended Squitter

definition: Contents of Extended Squitters transmitted by Military Aircraft

Compound

MES/SUM - Mode 5 Summary

Group

MES/SUM/M5

Element

bit size: 1

Values:

0:

No Mode 5 interrogation

1:

Mode 5 interrogation

MES/SUM/ID

Element

bit size: 1

Values:

0:

No authenticated Mode 5 ID reply/report

1:

Authenticated Mode 5 ID reply/report

MES/SUM/DA

Element

bit size: 1

Values:

0:

No authenticated Mode 5 Data reply or Report

1:

Authenticated Mode 5 Data reply or Report (i.e any valid Mode 5 reply type other than ID)

MES/SUM/M1

Element

bit size: 1

Values:

0:

Mode 1 code not present or not from Mode 5 reply/report

1:

Mode 1 code from Mode 5 reply/report

MES/SUM/M2

Element

bit size: 1

Values:

0:

Mode 2 code not present or not from Mode 5 reply/report

1:

Mode 2 code from Mode 5 reply/report

MES/SUM/M3

Element

bit size: 1

Values:

0:

Mode 3 code not present or not from Mode 5 reply/report

1:

Mode 3 code from Mode 5 reply/report

MES/SUM/MC

Element

bit size: 1

Values:

0:

Flightlevel not present or not from Mode 5 reply/report

1:

Flightlevel from Mode 5 reply/report

MES/SUM/PO

Element

bit size: 1

Values:

0:

Position not from Mode 5 report (ADS-B report)

1:

Position from Mode 5 report

Notes:

1. The flag M2 refers to the contents of Subfield #6 below, M3, MC refer to the contents of data items I021/070 and I021/145 respectively. The flag M1 refers to the contents of Subfield #3 below (Extended Mode 1 Code in Octal Representation).
2. If a Mode 5 reply/report is received with the Emergency bit set, then the Military Emergency bit (ME) in Data Item I021/200, Target Status, shall be set.
3. If a Mode 5 reply/report is received with the Identification of Position bit set, then the Special Position Identification bit (SPI) in Data Item I021/200, Target Status, shall be set.
4. If a Mode 5 report (ID or Data) is received and fullfill the autentication criteria the corresponding authentication bit shall be set.

MES/PNO - Mode 5 PIN / National Origin

Group

Spare bits: 2

MES/PNO/PIN - PIN Code

Element

bit size: 14

Raw Content

Spare bits: 5

MES/PNO/NO - National Origin Code

Element

bit size: 11

Raw Content

MES/EM1 - Extended Mode 1 Code in Octal Representation

Group

MES/EM1/V

Element

bit size: 1

Values:

0:

Code validated

1:

Code not validated

Spare bits: 1

MES/EM1/L

Element

bit size: 1

Values:

0:

Mode 1 code as derived from the report of the transponder

1:

Smoothed Mode 1 code as provided by a local tracker

Spare bits: 1

MES/EM1/EM1 - Extended Mode 1 Code in Octal Representation

Element

bit size: 12

Octal string (3-bits per char)

Notes:

• Subfield #1 is present, the M1 bit in Subfield #1 indicates whether the Extended Mode 1 Code is from a Mode 5 reply or a Mode 1 reply. If Subfield #1 is not present, the Extended Mode 1 Code is from a Mode 1 reply.
• If Subfield #3 is not present the Mode 1 Code was not reported or all Code Bits were equal to 0.
• The valid bit is set if the Code was only reported once for that target.

MES/XP - X Pulse Presence

Group

Spare bits: 2

MES/XP/XP - X-pulse from Mode 5 PIN Reply/report

Element

bit size: 1

Values:

0:

X-Pulse not present

1:

X-pulse present

MES/XP/X5 - X-pulse from Mode 5 Data Reply or Report

Element

bit size: 1

Values:

0:

X-pulse set to zero or no authenticated Data reply or Report received

1:

X-pulse set to one (present)

MES/XP/XC - X-pulse from Mode C Reply

Element

bit size: 1

Values:

0:

X-pulse set to zero or no Mode C reply

1:

X-pulse set to one (present)

MES/XP/X3 - X-pulse from Mode 3/A Reply

Element

bit size: 1

Values:

0:

X-pulse set to zero or no Mode 3/A reply

1:

X-pulse set to one (present)

MES/XP/X2 - X-pulse from Mode 2 Reply

Element

bit size: 1

Values:

0:

0 X-pulse set to zero or no Mode 2 reply

1:

X-pulse set to one (present)

MES/XP/X1 - X-pulse from Mode 1 Reply

Element

bit size: 1

Values:

0:

X-pulse set to zero or no Mode 1 reply

1:

X-pulse set to one (present)

Within Mode 5 reports, the X-Pulse can be set for the following cases:

1. In a combined Mode 1 and Mode 2 report: in this case the X5 bit and the X2 bit shall be set;

2. In a combined Mode 3 and Mode C report: in this case the X5 bit and the X3 bit shall be set;

3. In a Mode 5 PIN data report: in this case the X5 bit and the XP bit shall be set. The X1 bit and the XC bit are meaningless as in Mode 1 and Mode C replies/reports the X Pulse is not defined. They are kept for compatibility reasons.

MES/FOM - Figure of Merit

Group

Spare bits: 3

MES/FOM/FOM - Figure of Merit

Element

bit size: 5

Raw Content

MES/M2 - Mode 2 Code in Octal Representation

Group

MES/M2/V

Element

bit size: 1

Values:

0:

Code validated

1:

Code not validated

Spare bits: 1

MES/M2/L

Element

bit size: 1

Values:

0:

Mode-2 code as derived from the reply of the transponder

1:

Smoothed Mode-2 code as provided by a local tracker

Spare bits: 1

MES/M2/MODE2 - Mode 2 Code in Octal Representation

Element

bit size: 12

Octal string (3-bits per char)

If Subfield 6 is not present the Mode 2 Code was no reported or all Code Bits were equal to 0.

Notes:

• The Reserved Expansion Field is optional. When used to transmit MES, it shall be sent when the targets are represented by Mode 5 Level 2 reports.
• The information contained in this data item is specific to 1090MHz Extended Squitter messages transmitted by military aircraft (Mode 5 Level 2 squitter).