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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 />

Appendix C C-7<br />

C.2.3.1.1 Airborne Position Message TYPE Code<br />

C.2.3.1.1.1 Airborne Position Message TYPE Code if Containment Radius is Available<br />

Note.— If the position in<strong>for</strong>mation comes from a GNSS receiver that con<strong>for</strong>ms to the ARINC 743A<br />

characteristic, a suitable source of in<strong>for</strong>mation <strong>for</strong> the containment radius (RC), is ARINC 429 label 130 from<br />

that GNSS receiver.<br />

If RC (containment radius) in<strong>for</strong>mation is available from the navigation data source, then the transmitting<br />

ADS-B subsystem shall determine the TYPE Code (the value of the TYPE subfield) of Airborne Position<br />

Messages as follows.<br />

a. If current valid horizontal position in<strong>for</strong>mation is not available to the ADS-B Transmitting<br />

Subsystem, then the TYPE Code subfield of Airborne Position Messages shall be set to ZERO (0).<br />

b. If valid horizontal position <strong>and</strong> barometric pressure altitude in<strong>for</strong>mation are both available to the<br />

ADS-B Transmitting Subsystem, then the ADS-B Transmitting Subsystem shall set the TYPE Code<br />

subfield of Airborne Position Messages to a value in the range from 9 to 18 in accordance with<br />

Table C-2.<br />

c. If valid horizontal position in<strong>for</strong>mation is available to the ADS-B Transmitting Subsystem, but valid<br />

barometric pressure altitude in<strong>for</strong>mation is not available, <strong>and</strong> valid geometric altitude in<strong>for</strong>mation is<br />

available, the ADS-B Transmitting Subsystem shall set the TYPE Code subfield of Airborne<br />

Position Messages to a value in the range from 20 to 22 depending on the radius of containment<br />

(RC ) in accordance with Table C-2.<br />

d. If valid horizontal position in<strong>for</strong>mation is available to the ADS-B Transmitting Subsystem, but neither<br />

valid barometric altitude in<strong>for</strong>mation nor valid geometric altitude in<strong>for</strong>mation is available, the ADS-B<br />

Transmitting Subsystem shall set the TYPE Code subfield in Airborne Position Messages to a value<br />

in the range from 9 to 18 depending on the radius of containment RC in accordance with Table C-2.<br />

(In that case, the ALTITUDE subfield of the Airborne Position Messages shall be set to all ZEROs<br />

in order to indicate that valid altitude in<strong>for</strong>mation is not available.)<br />

C.2.3.1.1.2 Airborne Position Message TYPE Code if Containment Radius is Not<br />

Available<br />

Draft<br />

If RC (radius of containment) in<strong>for</strong>mation is NOT available from the navigation data source, then the ADS-B<br />

Transmitting Subsystem shall indicate NIC=0 by selecting a TYPE Code of 0, 18, or 22 in the Airborne<br />

Position Messages, as follows:<br />

a. The ADS-B Transmitting Subsystem shall set the TYPE Code subfield to ZERO (0) if valid<br />

horizontal position in<strong>for</strong>mation is not available.<br />

b. The ADS-B Transmitting Subsystem shall set the TYPE Code subfield to 18 if valid pressure<br />

altitude in<strong>for</strong>mation is available, or if neither valid pressure altitude nor valid geometric altitude<br />

in<strong>for</strong>mation is available.<br />

If valid pressure altitude is not available, but valid geometric altitude in<strong>for</strong>mation is available, the ADS-B<br />

Transmitting Subsystem shall set the TYPE Code subfield to 22.<br />

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

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