asterix specification

Asterix category 021 - ADS-B Target Reports

category: 021

edition: 0.23

date: 2003-11-01

Preamble

Surveillance data exchange. ADS-B Target Reports.

Description of standard data items

I021/010 - Data Source Identification

definition: Identification of the ADS-B station providing information.

Group

I021/010/SAC - System Area Code

Element

bit size: 8

Raw Content

I021/010/SIC - System Identification Code

Element

bit size: 8

Raw Content

Note:

I021/020 - Emitter Category

definition: Characteristics of the originating ADS-B unit.

Element

bit size: 8

Values:

1:
Light aircraft <= 7000 kg
2:
Reserved
3:
7000 kg < Medium aircraft < 136000 kg
4:
Reserved
5:
136000 kg <= Heavy aircraft
6:
Highly manoeuvrable (5g acceleration capability) and high speed (>400 knots cruise)
7:
Reserved
8:
Reserved
9:
Reserved
10:
Rotocraft
11:
Glider / sailplane
12:
Lighter-than-air
13:
Unmanned aerial vehicle
14:
Space / transatmospheric vehicle
15:
Ultralight / handglider / paraglider
16:
Parachutist / skydiver
17:
Reserved
18:
Reserved
19:
Reserved
20:
Surface emergency vehicle
21:
Surface service vehicle
22:
Fixed ground or tethered obstruction
23:
Reserved
24:
Reserved

I021/030 - Time of Day

definition: Time of applicability (measurement) of the reported position, in the form of elapsed time since last midnight, expressed as UTC.

Element

bit size: 24

Unsigned quantity

LSB = 1/27 s ≈ 7.8125e − 3 s

unit: "s"

The time of the day value is reset to zero at every midnight.

I021/032 - Time of Day Accuracy

definition: The maximum difference between the actual time of applicability of the reported position and the time reported in the Time of Day item (I021/030).

Element

bit size: 8

Unsigned quantity

LSB = 1/28 s ≈ 3.90625e − 3 s

unit: "s"

I021/040 - Target Report Descriptor

definition: Type and characteristics of the data as transmitted by a system.

Group

I021/040/DCR - Differential Correction

Element

bit size: 1

Values:

0:
No differential correction (ADS-B)
1:
Differential correction (ADS-B)

I021/040/GBS - Ground Bit Setting

Element

bit size: 1

Values:

0:
Ground Bit not set
1:
Ground Bit set

I021/040/SIM - Simulated Target

Element

bit size: 1

Values:

0:
Actual target report
1:
Simulated target report

I021/040/TST - Test Target

Element

bit size: 1

Values:

0:
Default
1:
Test Target

I021/040/RAB - Report Type

Element

bit size: 1

Values:

0:
Report from target transponder
1:
Report from field monitor (fixed transponder)

I021/040/SAA - Selected Altitude Available

Element

bit size: 1

Values:

0:
Equipment capable to provide Selected Altitude
1:
Equipment not capable to provide Selected Altitude

I021/040/SPI - Special Position Identification

Element

bit size: 1

Values:

0:
Absence of SPI
1:
Special Position Identification

Spare bits: 1

I021/040/ATP - Address Type

Element

bit size: 3

Values:

0:
Non unique address
1:
24-Bit ICAO address
2:
Surface vehicle address
3:
Anonymous address
4:
Reserved for future use
5:
Reserved for future use
6:
Reserved for future use
7:
Reserved for future use

I021/040/ARC - Altitude Reporting Capability

Element

bit size: 2

Values:

0:
Unknown
1:
25 ft
2:
100 ft

Spare bits: 3

I021/080 - Target Address

definition: Target address (emitter identifier) assigned uniquely to each target.

Element

bit size: 24

Raw Content

I021/090 - Figure of Merit

definition: ADS figure of merit (FOM) provided by the aircraft avionics.

Group

I021/090/AC - ACAS Capabilities

Element

bit size: 2

Values:

0:
Unknown
1:
ACAS not operational
2:
ACAS operartional
3:
Invalid

I021/090/MN - Multiple Navigation Aids

Element

bit size: 2

Values:

0:
Unknown
1:
Multiple Navigation not operational
2:
Multiple Navigation operartional
3:
Invalid

I021/090/DC - Differencial Correction

Element

bit size: 2

Values:

0:
Unknown
1:
Differencial Correction
2:
NO Differencial Correction
3:
Invalid

Spare bits: 6

I021/090/PA - Position Accuracy

Element

bit size: 4

Signed quantity

LSB = 1 ≈ 1.0

unit: ""

Note:

bits-4/1 (PA) code the “Navigational Uncertainty Categories – Position” as described in the ADS-B MASPS [Ref. 3]

I021/095 - Velocity Accuracy

definition: Velocity uncertainty category of the least accurate velocity

Element

bit size: 8

Raw Content

Note:

bits-8/1 code the “Navigational Uncertainty Categories – Velocity” as described in the ADS-B MASPS [Ref. 3]

I021/110 - Trajectory Intent

definition: Reports indicating the 4D intended trajectory of the aircraft.

Compound

I021/110/TIS - Trajectory Intent Status

Extended

I021/110/TIS/NAV

Element

bit size: 1

Values:

0:
Trajectory Intent Data is available for this aircraft
1:
Trajectory Intent Data is not available for this aircraft

I021/110/TIS/NVB

Element

bit size: 1

Values:

0:
Trajectory Intent Data is valid
1:
Trajectory Intent Data is not valid

Spare bits: 5

(FX) - extension bit

I021/110/TID - Trajectory Intent Data

Repetitive

Regular, 1 byte(s) REP field size.

Group

I021/110/TID/TCA

Element

bit size: 1

Values:

0:
TCP number available
1:
TCP number not available

I021/110/TID/NC

Element

bit size: 1

Values:

0:
TCP compliance
1:
TCP non-compliance

I021/110/TID/TCPN

description: Trajectory Change Point number

Element

bit size: 6

Raw Content

I021/110/TID/ALT - Altitude in Two's Complement Form

Element

bit size: 16

Signed quantity

LSB = 10 ft ≈ 10.0 ft

unit: "ft"

>= −1500.0

<= 150000.0

I021/110/TID/LAT - In WGS.84 in Two's Complement

Element

bit size: 24

Signed quantity

LSB = 180/223 ° ≈ 2.1457672119140625e − 5 °

unit: "°"

>= −90.0

<= 90.0

I021/110/TID/LON - In WGS.84 in Two's Complement

Element

bit size: 24

Signed quantity

LSB = 180/223 ° ≈ 2.1457672119140625e − 5 °

unit: "°"

>= −180.0

< 180.0

I021/110/TID/PT - Point Type

Element

bit size: 4

Values:

0:
Unknown
1:
Fly by waypoint (LT)
2:
Fly over waypoint (LT)
3:
Hold pattern (LT)
4:
Procedure hold (LT)
5:
Procedure turn (LT)
6:
RF leg (LT)
7:
Top of climb (VT)
8:
Top of descent (VT)
9:
Start of level (VT)
10:
Cross-over altitude (VT)
11:
Transition altitude (VT)

I021/110/TID/TD

Element

bit size: 2

Values:

0:
N/A
1:
Turn right
2:
Turn left
3:
No turn

I021/110/TID/TRA

description: Turn Radius Availability

Element

bit size: 1

Values:

0:
TTR not available
1:
TTR available

I021/110/TID/TOA

Element

bit size: 1

Values:

0:
TOV available
1:
TOV not available

I021/110/TID/TOV - Time Over Point

Element

bit size: 24

Unsigned quantity

LSB = 1 s ≈ 1.0 s

unit: "s"

I021/110/TID/TTR - TCP Turn Radius

Element

bit size: 16

Unsigned quantity

LSB = 1/100 NM ≈ 1.0e − 2 NM

unit: "NM"

>= 0.0

<= 655.35

Notes:

  1. NC is set to one when the aircraft will not fly the path described by the TCP data.
  2. TCP numbers start from zero.
  3. LT = Lateral Type
  4. VT = Vertical Type
  5. TOV gives the estimated time before reaching the point. It is defined as the absolute time from midnight.
  6. TOV is meaningful only if TOA is set to 1.

I021/130 - Position in WGS-84 Co-ordinates

definition: Position in WGS-84 Co-ordinates.

Group

I021/130/LAT - Latitude

Element

bit size: 24

Signed quantity

LSB = 180/223 ° ≈ 2.1457672119140625e − 5 °

unit: "°"

>= −90.0

<= 90.0

I021/130/LON - Longitude

Element

bit size: 24

Signed quantity

LSB = 180/223 ° ≈ 2.1457672119140625e − 5 °

unit: "°"

>= −180.0

< 180.0

Note:

Positive longitude indicates East. Positive latitude indicates North.

I021/140 - Geometric Altitude

definition: Minimum height from a plane tangent to the earth’s ellipsoid, defined by WGS-84, in two’s complement form.

Element

bit size: 16

Signed quantity

LSB = 25/22 ft ≈ 6.25 ft

unit: "ft"

>= −1500.0

< 150000.0

Note:
  1. LSB is required to be less than 10 ft by ICAO.

I021/145 - Flight Level

definition: Flight Level from barometric measurements,not QNH corrected, in two’s complement form.

Element

bit size: 16

Signed quantity

LSB = 1/22 FL ≈ 0.25 FL

unit: "FL"

>= −15.0

< 1500.0

I021/146 - Intermediate State Selected Altitude

definition: The short-term vertical intent as described by either the FMS selected altitude, the Altitude Control Panel Selected Altitude, or the current aircraft altitude according to the aircraft's mode of flight.

Group

I021/146/SAS - Source Availability

Element

bit size: 1

Values:

0:
No source information provided
1:
Source Information provided

I021/146/SRC - Source

Element

bit size: 2

Values:

0:
Unknown
1:
Aircraft Altitude (Holding Altitude)
2:
MCP/FCU Selected Altitude
3:
FMS Selected Altitude

I021/146/ALT - Altitude

Element

bit size: 13

Signed quantity

LSB = 25 ft ≈ 25.0 ft

unit: "ft"

>= −1300.0

< 100000.0

I021/148 - Final State Selected Altitude

definition: The vertical intent value that corresponds with the ATC cleared altitude, as derived from the Altitude Control Panel (MCP/FCU).

Group

I021/148/MV - Manage Vertical Mode

Element

bit size: 1

Values:

0:
Not active
1:
Active

I021/148/AH - Altitude Hold Mode

Element

bit size: 1

Values:

0:
Not active
1:
Active

I021/148/AM - Approach Mode

Element

bit size: 1

Values:

0:
Not active
1:
Active

I021/148/ALT - Altitude

Element

bit size: 13

Signed quantity

LSB = 25 ft ≈ 25.0 ft

unit: "ft"

>= −1300.0

< 100000.0

I021/150 - Air Speed

definition: Calculated Air Speed (Element of Air Vector).

Group

I021/150/IM

Element

bit size: 1

Values:

0:
Air Speed = IAS, LSB (Bit-1) = 2 -14 NM/s
1:
Air Speed = Mach, LSB (Bit-1) = 0.001

I021/150/AS - Air Speed (IAS or Mach)

Element

bit size: 15

Depending on: (150/IM)

(0):

Unsigned quantity

LSB = 1/214 NM/s ≈ 6.103515625e − 5 NM/s

unit: "NM/s"

(1):

Unsigned quantity

LSB = 1/1000 Mach ≈ 1.0e − 3 Mach

unit: "Mach"

Default:

Raw Content

I021/151 - True Airspeed

definition: True Air Speed.

Element

bit size: 16

Unsigned quantity

LSB = 1 kt ≈ 1.0 kt

unit: "kt"

I021/152 - Magnetic Heading

definition: Magnetic Heading (Element of Air Vector).

Element

bit size: 16

Unsigned quantity

LSB = 360/216 ° ≈ 5.4931640625e − 3 °

unit: "°"

I021/155 - Barometric Vertical Rate

definition: Barometric Vertical Rate, in two’s complement form.

Element

bit size: 16

Signed quantity

LSB = 25/22 ft/min ≈ 6.25 ft/min

unit: "ft/min"

I021/157 - Geometric Vertical Rate

definition: Geometric Vertical Rate, in two’s complement form, with reference to WGS-84.

Element

bit size: 16

Signed quantity

LSB = 25/22 ft/min ≈ 6.25 ft/min

unit: "ft/min"

I021/160 - Ground Vector

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

Group

I021/160/GS - Ground Speed in Two's Complement Form Referenced to WGS84

Element

bit size: 16

Signed quantity

LSB = 1/214 NM/s ≈ 6.103515625e − 5 NM/s

unit: "NM/s"

>= 0.0

< 2.0

I021/160/TA - Track Angle

Element

bit size: 16

Unsigned quantity

LSB = 360/216 ° ≈ 5.4931640625e − 3 °

unit: "°"

I021/165 - Rate Of Turn

definition: Rate of Turn, in two’s complement form.

Extended

I021/165/TI - Turn Indicator

Element

bit size: 2

Values:

0:
Not available
1:
Left
2:
Right
3:
Straight

Spare bits: 5

(FX) - extension bit

I021/165/ROT - Rate of Turn

Element

bit size: 7

Signed quantity

LSB = 1/22 °/s ≈ 0.25 °/s

unit: "°/s"

<= 15.0

(FX) - extension bit

Notes:
  1. A positive value represents a right turn, whereas a negative value represents a left turn.
  2. Value 15 means 15 °/s or above.

I021/170 - Target Identification

definition: Target (aircraft or vehicle) identification in 8 characters, as reported by the target.

Element

bit size: 48

ICAO string (6-bits per char)

I021/200 - Target Status

definition: Status of the target

Element

bit size: 8

Values:

0:
No emergency / not reported
1:
General emergency
2:
Lifeguard / medical
3:
Minimum fuel
4:
No communications
5:
Unlawful interference

I021/210 - Link Technology Indicator

definition: Indication of which ADS link technology has been used to send the target report.

Group

Spare bits: 3

I021/210/DTI - Cockpit Display of Traffic Information

Element

bit size: 1

Values:

0:
Unknown
1:
Aircraft equiped with CDTI

I021/210/MDS - Mode-S Extended Squitter

Element

bit size: 1

Values:

0:
Not used
1:
Used

I021/210/UAT - UAT

Element

bit size: 1

Values:

0:
Not used
1:
Used

I021/210/VDL - VDL Mode 4

Element

bit size: 1

Values:

0:
Not used
1:
Used

I021/210/OTR - Other Technology

Element

bit size: 1

Values:

0:
Not used
1:
Used

I021/220 - Met Information

definition: Meteorological information.

Compound

I021/220/WS - Wind Speed

Element

bit size: 16

Unsigned quantity

LSB = 1 kt ≈ 1.0 kt

unit: "kt"

>= 0.0

<= 300.0

I021/220/WD - Wind Direction

Element

bit size: 16

Unsigned quantity

LSB = 1 ° ≈ 1.0 °

unit: "°"

>= 1.0

<= 360.0

I021/220/TMP - Temperature

Element

bit size: 16

Signed quantity

LSB = 1/22 °C ≈ 0.25 °C

unit: "°C"

>= −100.0

<= 100.0

I021/220/TRB - Turbulence

Element

bit size: 8

Unsigned integer

>= 0.0

<= 15.0

I021/230 - Roll Angle

definition: The roll angle, in two’s complement form, of an aircraft executing a turn.

Element

bit size: 16

Signed quantity

LSB = 1/100 ° ≈ 1.0e − 2 °

unit: "°"

>= −180.0

<= 180.0

Notes:
  1. Negative Value indicates “Left Wing Down”.
  2. Resolution provided by the technology “1090 MHz Extended Squitter” is 1 degree.

I021/RE - Reserved Expansion Field

definition: Expansion

Explicit (ReservedExpansion)

I021/SP - Special Purpose Field

definition: Special Purpose Field

Explicit (SpecialPurpose)

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