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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 />

DE-8 <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 />

D.2.15 CAPABILITY/MODE CODES<br />

This 2-bit (ME bits 52 — 53, Message bits 84 — 85) subfield shall be used to indicate the current operational status of<br />

TCAS/ACAS systems/functions. This subfield shall be encoded as specified in the following table. If an update has not<br />

been received from an on-board data source <strong>for</strong> a Capability/<strong>Mode</strong> Code data element within the past 2 seconds, then<br />

that data element shall be encoded with a value of zero (0).<br />

Coding Meaning<br />

ME bit 52 = 0 TCAS/ACAS operational or unknown<br />

ME bit 52 = 1 TCAS/ACAS not operational<br />

ME bit 53 = 0 No TCAS/ACAS Resolution Advisory active<br />

ME bit 53 = 1 TCAS/ACAS Resolution Advisory active<br />

D.2.16 EMERGENCY/PRIORITY STATUS<br />

This 3-bit (ME bits 54 — 56, message bits 86 — 88) subfield shall be used to provide additional in<strong>for</strong>mation regarding<br />

aircraft status. The Emergency/Priority Status subfield shall be encoded as specified in the following table. If an update<br />

has not been received from an on-board data source <strong>for</strong> the Emergency/Priority Status within the past 5 seconds, then<br />

the emergency/priority status subfield shall be encoded with a value indicating no emergency.<br />

Coding<br />

(Binary) (Decimal) Meaning<br />

000 0 No emergency<br />

001 1 General emergency<br />

Draft<br />

010 2 Lifeguard/medical emergency<br />

011 3 Minimum fuel<br />

100 4 No communications<br />

101 5 Unlawful interference<br />

110 6 Downed aircraft<br />

111 7 Reserved<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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