User's Manual

SYSTEM DESCRIPTION AND INSTALLATION MANUAL
T
3
CAS/Part No.9005000
Table 1-27: Downlink Format Fields (cont.)
Designator
Field
Description
UM
Utility Message
Contains the transponder status readouts
VS
Vertical Status
Reports the aircraft airborne or on-ground state
(3) Mode S ELS/EHS and ADS-B OUT
Traditional Secondary Surveillance Radar (SSR) includes Mode 3/A (aircraft
identification or 4096 code) and Mode C (uncorrected barometric altitude
reporting). Then to increase ATC capacity which included implementing TCAS
operation, Mode S was developed which made transponder interrogations
addressable and transponder replies more accurate and reliable. Basic Mode S
requires the aircraft to be;
● equipped with a Mode S capable transponder
● equipped with a means for the operator to enter the ATC assigned 4096
code that then provides standard ARINC 429 label 016 Mode S Control
● equipped with a source of uncorrected barometric altitude with at least 100
feet resolution via one of the following:
- standard ARINC 429 label 203 Uncorrected Barometric Altitude
- standard ARINC 575 label 203 Uncorrected Barometric Altitude
- standard ARINC 407 Coarse and Fine Synchro Uncorrected Barometric
Altitude
- dual Gillham Code uncorrected pressure altitude.
- strapped with the aircraft's unique 24-bit ICAO aircraft address.
Mode S Elementary Surveillance (ELS) was the first step of down linking
additional aircraft derived data. In addition to the Mode S aircraft requirements
listed above, minimally Mode S ELS requires the aircraft to be:
● equipped with a Mode S ELS capable transponder
● equipped with a means for the operator to enter Flight Identification that then
provides standard ARINC 429 labels:
- 233, 301 Characters 1 and 2
- 234, 301 Character 3
- 234, 302 Character 4
- 235. 302 Characters 5 and 6
- 236 Characters 7 and 8.
● equipped with a source of uncorrected barometric altitude source with at
least 25 feet resolution with the exception of dual Gillham code uncorrected
barometric altitude sources with 100 feet resolution via one of the following:
- Standard ARINC 429 label 203 Uncorrected Barometric Altitude
- Standard ARINC 575 label 203 Uncorrected Barometric Altitude
- Standard ARINC 407 Coarse and Fine Synchro Uncorrected Barometric
Altitude
- Dual Gillham Code uncorrected barometric altitude.
Pub. No. 8600200-001, Revision 004
34-45-29
1-119
04 Nov 2014
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