AMC1 ACNS.D.ELS.015 Data transmission

• ED Decision 2022/008/R found in: GM Remote Aerodrome Air Traffic Services (ED 2019/004/R) Issue 2 (Jul 2020)

AMC1 ACNS.D.ELS.015 Data transmission ED Decision 2022/008/R Data transmission verifications (a) Table 1 below provides the parameters that should be verified for Mode S elementary surveillance. Table 1 — List of parameters to be verified on an ELS installation <table border="1" cellpadding="0" cellspacing="0" width="567"><tr><td valign="top" width="41"><p>Item</p></td><td valign="top" width="177"><p>Parameters</p></td><td valign="top" width="170"><p>Message/register</p></td><td valign="top" width="180"><p>Remark</p></td></tr><tr><td valign="top" width="41"><p>1</p></td><td valign="top" width="177"><p>Mode A code and Emergency status</p></td><td valign="top" width="170"><p>DF5 and DF21</p></td><td valign="top" width="180"><p>Note 3</p></td></tr><tr><td valign="top" width="41"><p>2</p></td><td valign="top" width="177"><p>Pressure altitude</p></td><td valign="top" width="170"><p>DF4 and DF20</p></td><td valign="top" width="180"><p>See (b) and (c)</p></td></tr><tr><td valign="top" width="41"><p>3</p></td><td valign="top" width="177"><p>On-the-ground status</p></td><td valign="top" width="170"><p>CA field in DF11 or FS field in DF4/5/20/21</p></td><td valign="top" width="180"></td></tr><tr><td valign="top" width="41"><p>4</p></td><td valign="top" width="177"><p>Aircraft Identification</p></td><td valign="top" width="170"><p>Register 20₁₆</p></td><td valign="top" width="180"><p>See (d)</p></td></tr><tr><td valign="top" width="41"><p>5</p></td><td valign="top" width="177"><p>SPI</p></td><td valign="top" width="170"><p>DF4/5/20/21</p></td><td valign="top" width="180"><p>See (e)</p></td></tr><tr><td valign="top" width="41"><p>6a</p></td><td valign="top" width="177"><p>Capability report </p></td><td valign="top" width="170"><p>CA field in DF11 </p></td><td valign="top" width="180"></td></tr><tr><td valign="top" width="41"><p>6b</p></td><td valign="top" width="177"><p>Data-link capability report and common usage GICB capability report</p></td><td valign="top" width="170"><p>Register 10₁₆ Register 17₁₆</p></td><td valign="top" width="180"><p>(g)</p></td></tr><tr><td valign="top" width="41"><p>7</p></td><td valign="top" width="177"><p>ICAO 24 bit aircraft address</p></td><td valign="top" width="170"><p>DF11</p></td><td valign="top" width="180"></td></tr><tr><td valign="top" width="41"><p>8</p></td><td valign="top" width="177"><p>RA report</p></td><td valign="top" width="170"><p>Register 30₁₆ + announcement in DF4/5/20/21</p></td><td valign="top" width="180"><p>Only for ACAS installation see (f)</p></td></tr></table> Note 1: Information about how Mode S ELS data is used by Mode S ground systems can be found in Subpart D, [*Appendix B*](#_DxCrossRefBm573002698). Note 2: Downlink formats (DFs) are defined in ICAO Annex 10, Volume IV and EUROCAE ED-73E. A summary can also be found in Subpart D, [*Appendix B*](#_DxCrossRefBm573002698). Note 3: It is not recommended to have 2 transponders installed without a common control panel. (b) Pressure Altitude (1) The consistency of the altitude reported in Mode C replies and Mode S replies should be checked. Note: An incorrect installation of altimeters using Gillham encoding may result in altitude transmitted in Mode C replies and no altitude transmitted in Mode S replies. (2) For aircraft transmitting parameters via the Extended Squitter, for which compliance with Subpart D section 4 is not required, the pressure altitude data should be checked in the Extended Squitter register for airborne position (register 0516). (c) Pressure altitude resolution transmission (1) The resolution of the transmitted pressure altitude should be 7.62 m (25 ft) for aircraft equipped with a pressure altitude source having a resolution better than 7.62 m (25 ft) for all altitudes except those above 15 298 m (50 187.5 ft). (2) Aircraft equipped with altimeters that have a resolution greater than 7.62 m (25 ft) (e.g. 30.48 m (100 ft)) should report their altitude in 30.48 m (100 ft) encoding. (3) Verify that the encoding of the altitude is appropriate to the altimeter resolution as defined in paragraphs 1 and 2 above. (4) For aircraft transmitting parameters via the Extended Squitter, for which compliance with Subpart D section 4 is not required, the pressure altitude resolution data should be checked in the Extended Squitter register for airborne position (register 0516). (d) Aircraft Identification (1) For aircraft transmitting parameters via the Extended Squitter, for which compliance with Subpart D section 4 is not required, the Aircraft Identification received via the Extended Squitter should be checked to ensure that it is identical to the information transmitted in register 2016. (e) Special Position Indication (SPI) The FS field should report FS = 4 or 5 for 18 seconds (+/-1 second) in replies DF4, DF5, DF20 or DF21 after the SPI (IDENT) has been manually activated. Note: Flight Status values can be found in ICAO Annex 10, Vol IV, paragraph 3.1.2.6.5.1. (f) ACAS active Resolution Advisory report For aircraft that have ACAS II installed, no undue RA report should be announced (DR field never set to 2, 3, 6 or 7) within (5 minutes). (g) Common usage GICB capability report: BDS 1716 = 0 is an acceptable means of compliance for transponders that are strictly ELS (not transmitting other parameters). (h) Transmission of other parameters When one or more other airborne data items are transmitted, they should be verified as proposed in [AMC1 ACNS.D.EHS.015](#_DxCrossRefBm573002707). Note 1: The minimum data transmission verification of transponder also having ADS-B ES capabilities has been defined above. Transponders that are transmitting parameters other than the minimum tested above, are encouraged to demonstrate compliance with Subpart D section 4. Note 2: The implementation of registers E316, E416, E516 and E616 is recommended. [Issue: CS-ACNS/4]