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Technical Provisions for Mode S Services and Extended Squitter

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DRAFT - Working Paper ASP TSGWP11-01 <strong>for</strong> review by the TSG during the meeting in June 2011 in Paris<br />

C-92 <strong>Technical</strong> <strong>Provisions</strong> <strong>for</strong> <strong>Mode</strong> S <strong>Services</strong> <strong>and</strong> <strong>Extended</strong> <strong>Squitter</strong><br />

Version 0<br />

Airborne<br />

Velocity<br />

Message<br />

SUBTYPE<br />

Table C-45. Track/Heading <strong>and</strong> HRD Subfield<br />

Airborne<br />

Velocity<br />

Message<br />

“Magnetic<br />

Heading Status<br />

Bit”<br />

Surface<br />

Position<br />

Message<br />

“Ground<br />

Track Status<br />

Bit”<br />

N/A N/A 0<br />

1 or 2 N/A 1<br />

3 or 4 0 N/A<br />

3 or 4 1 N/A<br />

Meaning<br />

No Valid Track/<br />

Heading or<br />

Heading Direction<br />

Reference<br />

in<strong>for</strong>mation<br />

available<br />

Ground Track<br />

being reported<br />

Heading relative<br />

to true north being<br />

reported<br />

Heading relative<br />

to magnetic north<br />

being reported<br />

ADS-B<br />

Report<br />

True/Magnetic<br />

Heading subfield<br />

encoding<br />

Notes.—<br />

1. When no valid data is available the “Track/Heading <strong>and</strong> HRD” parameter may be reported as ALL<br />

ZEROs.<br />

2. When receiving ADS-B Version Two (2) Messages, the Track/Heading <strong>and</strong> HRD in<strong>for</strong>mation are<br />

conveyed within the Operation Status Message. However, when receiving ADS-B Version Zero (0)<br />

Messages the equivalent in<strong>for</strong>mation can be determined <strong>for</strong> airborne aircraft from the value of the “Subtype”<br />

subfield <strong>and</strong> <strong>for</strong> Subtype=3 or 4 messages the value of the “Magnetic Heading Status Bit” of the Airborne<br />

Velocity Message (Table A-2-9b). When a target aircraft/vehicle is on the surface, a value of 01 should be<br />

reported when a Surface Position Message (Table A-2-6) is received with the “Heading/Ground Track Status<br />

Bit” set to a value of ONE (1) indicating that the valid ground track data is provided.<br />

3. ADS-B Version Zero (0) Airborne Velocity Messages, Subtypes 3 <strong>and</strong> 4 always report Heading<br />

relative to Magnetic North, never relative to True North.<br />

C.5.2.3 AIR REFERENCED VELOCITY REPORTS<br />

Draft<br />

The requirements <strong>for</strong> Air Referenced Velocity (ARV) Reports shall apply to the ARV Report Assembly<br />

requirements when the target aircraft is broadcasting either ADS-B Version Zero (0) or Version Two (2)<br />

Message <strong>for</strong>mats (Table A-2-9b).<br />

C.5.2.4 TARGET STATUS REPORTS<br />

Appendix A defines a message <strong>for</strong>mat using message TYPE Code 29 to convey Aircraft Trajectory Intent<br />

in<strong>for</strong>mation in the <strong>for</strong>m of Trajectory Change Point (TCP) in<strong>for</strong>mation. A 1090 MHz ADS-B Receiving<br />

Subsystem con<strong>for</strong>ming to this Manual does shall not use any message with a TYPE Code of 29 that is<br />

received from a ADS-B Version Zero (0) Transmitting Subsystem <strong>for</strong> the purpose of report generation.<br />

Note.— Prior to generation of a Target Status Report, the 1090 MHz ADS-B Receiving Subsystem must<br />

positively confirm that any received message with a TYPE Code of 29 has originated from a target aircraft<br />

with an ADS-B Version Number other than Zero (0). The ADS-B Version Number can be determined from<br />

the contents of the ADS-B Version Number subfield (see §C.2.3.10.5) of the Aircraft Operational Status<br />

Message.<br />

DRAFT - Working Paper ASP TSGWP11-01 <strong>for</strong> review by the TSG during the meeting in June 2011 in Paris<br />

00<br />

01<br />

00<br />

11

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