Publication: Magyar Közlöny
Issue: MK-2007-70 (Year: 2007, Number: 70)
Era: 2004-2010
Section: Melléklet a 2007. évi XLVI. törvényhez
Paragraph Index: 4707

c) the range of the detected aircraft is greater than 5.6 km (3 NM) and the calculated time to closest approach exceeds 60 seconds, assuming that both the detected and own aircraft proceed from their current positions with unaccelerated motion and that the range at closest approach equals 5.6 km (3 NM). 4.3.7.1.2.2.1 Range acquisition interrogations. ACAS shall use the short air-air surveillance format (UF = 0) for range acquisition. ACAS shall set AQ = 1 (Chapter 3, 3.1.2.8.1.1) and RL = 0 (Chapter 3, 3.1.2.8.1.2) in an acquisition interrogation. Note 1.— Setting AQ = 1 results in a reply with bit 14 of the RI field equal to 1 and serves as an aid in distinguishing the reply to own interrogation from replies elicited from other ACAS units (4.3.7.1.2.2.2). Note 2.— In the acquisition interrogation RL is set to 0 to command a short acquisition reply (DF = 0). 4.3.7.1.2.2.2 Tracking interrogations. ACAS shall use the short air-air surveillance format (UF = 0) with RL = 0 and AQ = 0 for tracking interrogations. 4.3.7.1.2.3 Surveillance replies. These protocols are described in 4.3.11.3.1. 4.3.7.1.2.4 ACAS broadcast. An ACAS broadcast shall be made nominally every 8 to 10 s at full power from the top antenna. Installations using directional antennas shall operate such that complete circular coverage is provided nominally every 8 to 10 s. Note.— A broadcast causes other Mode S transponders to accept the interrogation without replying and to present the interrogation content containing the MU field at the transponder output data interface. The UDS1 = 3, UDS2 = 2 combination identifies the data as an ACAS broadcast containing the 24-bit address of the interrogating ACAS aircraft. This provides each ACAS with a means of determining the number of other ACAS within its detection range for limiting interference. The format of the MU field is described in 4.3.8.4.2.3. 4.3.7.2 AIR-AIR COORDINATION PROTOCOLS 4.3.7.2.1 Coordination interrogations. ACAS shall transmit UF = 16 interrogations (Chapter 3, 3.1.2.3.2, Figure 3-7) with AQ = 0 and RL = 1 when another aircraft reporting RI = 3 or 4 is declared a threat (4.3.4). The MU field shall contain the resolution message in the subfields specified in 4.3.8.4.2.3.2. Note 1.— A UF = 16 interrogation with AQ = 0 and RL = 1 is intended to cause a DF = 16 reply from the other aircraft. Note 2.— An aircraft reporting RI = 3 or RI = 4 is an aircraft equipped with an operating ACAS which has vertical only or vertical and horizontal resolution capability, respectively. 4.3.7.2.2 Coordination reply. These protocols are described in 4.3.11.3.2. 2007/70/II. szám Chapter 4 Annex 10 — Aeronautical Telecommunications 4-15 28/11/02 4.3.7.3 PROTOCOLS FOR ACAS COMMUNICATION WITH GROUND STATIONS 4.3.7.3.1 RA reports to Mode S ground stations. These protocols are described in 4.3.11.4.1. 4.3.7.3.2 RA broadcasts. RA broadcasts shall be transmitted at full power from the bottom antenna at jittered, nominally 8 s intervals for the period that the RA is indicated. The RA broadcast shall include the MU field as specified in 4.3.8.4.2.3.4. The RA broadcast shall describe the most recent RA that existed during the preceding 8 s period. Installations using directional antennas shall operate such that complete circular coverage is provided nominally every 8 s and the same RA sense and strength is broadcast in each direction. 4.3.7.3.3 Data link capability report. These protocols are described in 4.3.11.4.2. 4.3.7.3.4 ACAS sensitivity level control. ACAS shall act upon an SLC command if and only if TMS (Chapter 3, 3.1.2.6.1.4.1) has the value 0 and DI is either 1 or 7 in the same interrogation. 4.3.8 Signal formats 4.3.8.1 The RF characteristics of all ACAS signals shall conform to the Standards of Chapter 3, 3.1.1.1 through 3.1.1.6, 3.1.2.1 through 3.1.2.3, 3.1.2.5 and 3.1.2.8. 4.3.8.2 RELATIONSHIP BETWEEN ACAS AND MODE S SIGNAL FORMATS Note.— ACAS uses Mode S transmissions for surveillance and communications. ACAS air-air communication functions permit RA decisions to be coordinated with ACAS-equipped threats. ACAS air-ground communication functions permit the reporting of RAs to ground stations and the uplinking of commands to ACAS-equipped aircraft to control parameters of the collision avoidance algorithms. 4.3.8.3 Signal format conventions. The data encoding of all ACAS signals shall conform to the Standards of Chapter 3, 3.1.2.3. Note.— In air-air transmissions used by ACAS, interrogations transmitted at 1 030 MHz are designated as uplink transmissions and contain uplink format (UF) codes. Replies received at 1 090 MHz are designated as downlink transmissions and contain downlink format (DF) codes. 4.3.8.4 FIELD DESCRIPTION Note 1.— The air-air surveillance and communication formats which are used by ACAS but not fully described in Chapter 3, 3.1.2 are given in Figure 4-1. Uplink: Downlink: Figure 4-1. Surveillance and communication formats used by ACAS UF = 0 RL:1 AQ:1 AP:24 UF = 16 RL:1 AQ:1 MU:56 AP:24 DF = 0 VS:1 SL:3 RI:4 AC:13 AP:24 DF = 16 VS:1 SL:3 RI:4 AC:13 MV:56 AP:24 – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 4-16 Note 2.— This section defines the Mode S fields (and their subfields) that are processed by ACAS to accomplish ACAS functions. Some of the ACAS fields (those also used for other SSR Mode S functions) are described with unassigned ACAS codes in Chapter 3, 3.1.2.6. Such codes are assigned in 4.3.8.4.1. Fields and subfields used only by ACAS equipment are assigned in 4.3.8.4.2. Note 3.— The bit numbering convention used in 4.3.8.4 reflects the bit numbering within the entire uplink or downlink format rather than the bits within individual fields or subfields. 4.3.8.4.1 FIELDS AND SUBFIELDS INTRODUCED IN CHAPTER 3, 3.1.2 Note.— Codes for mission fields and subfields that are designated “reserved for ACAS” in Chapter 3, 3.1.2, are specified in this section. 4.3.8.4.1.1 DR (downlink request). The significance of the coding of the downlink request field shall be as follows: 4.3.8.4.1.2 RI (air-air reply information). The significance of the coding in the RI field shall be as follows: Bit 14 of the reply format containing this field shall replicate the AQ bit of the interrogation. The RI field shall report “no operating ACAS” (RI = 0) if the ACAS unit has failed or is in standby. The RI field shall report “ACAS with resolution capability inhibited” (RI = 2) if sensitivity level is 2 or TA only mode has been selected. Note.— Codes 0-7 in the RI field indicate that the reply is a tracking reply and also give the ACAS capability of the interrogated aircraft. Codes 8-15 indicate that the reply is an acquisition reply and also give the maximum true airspeed capability of the interrogated aircraft. 4.3.8.4.1.3 RR (reply request). The significance of the coding in the reply request field shall be as follows: 4.3.8.4.2 ACAS FIELDS AND SUBFIELDS Note.— The following paragraphs describe the location and coding of those fields and subfields that are not defined in Chapter 3, 3.1.2 but are used by aircraft equipped with ACAS. Coding 0-1 See Chapter 3, 3.1.2.6.5.2 ACAS message available Comm-B message available and ACAS message available 4-5 See Chapter 3, 3.1.2.6.5.2 Comm-B broadcast message 1 available and ACAS message available Comm-B broadcast message 2 available and ACAS message available 8-31 See Chapter 3, 3.1.2.6.5.2 Coding No operating ACAS Not assigned ACAS with resolution capability inhibited ACAS with vertical-only resolution capability ACAS with vertical and horizontal resolution capability 5-7 Not assigned 8-15 See Chapter 3, 3.1.2.8.2.2 Coding 0-18 See Chapter 3, 3.1.2.6.1.2 Transmit a resolution advisory report 20-31 See Chapter 3, 3.1.2.6.1.2 2007/70/II. szám Chapter 4 Annex 10 — Aeronautical Telecommunications 4-17 28/11/02 4.3.8.4.2.1 Subfield in MA 4.3.8.4.2.1.1 ADS (A-definition subfield). This 8-bit (33-40) subfield shall define the remainder of MA. Note.— For convenience of coding, ADS is expressed in two groups of four bits each, ADS1 and ADS2. 4.3.8.4.2.1.2 When ADS1 = 0 and ADS2 = 5, the following subfield shall be contained in MA: 4.3.8.4.2.1.3 SLC (ACAS sensitivity level control (SLC) command). This 4-bit (41-44) subfield shall denote a sensitivity level command for own ACAS. Note.— Structure of MA for a sensitivity level control command: 4.3.8.4.2.2 Subfields in MB 4.3.8.4.2.2.1 Subfields in MB for an RA report. When BDS1 = 3 and BDS2 = 0, the subfields indicated below shall be contained in MB. For 18±1 s following the end of an RA, all MB subfields in the RA report with the exception of bit 59 (RA terminated indicator) shall retain the information reported at the time the RA was last active. 4.3.8.4.2.2.1.1 ARA (active RAs). This 14-bit (41-54) subfield shall indicate the characteristics of the RA, if any, generated by the ACAS associated with the transponder transmitting the subfield (4.3.6.2.1 a)). The bits in ARA shall have meanings determined by the value of the MTE subfield (4.3.8.4.2.2.1.4) and, for vertical RAs, the value of bit 41 of ARA. The meaning of bit 41 of ARA shall be as follows: When ARA bit 41 = 1 and MTE = 0 or 1, bits 42-47 shall have the following meanings: Coding No command issued Not assigned Set ACAS sensitivity level to 2 Set ACAS sensitivity level to 3 Set ACAS sensitivity level to 4 Set ACAS sensitivity level to 5 Set ACAS sensitivity level to 6 7-14 Not assigned Cancel previous SLC command from this ground station ADS1 = 0 ADS2 = 5 SLC – – – – 44 – – – – Coding There is more than one threat and the RA is intended to provide separation below some threat(s) and above some other threat(s) or no RA has been generated (when MTE = 0) Either there is only one threat or the RA is intended to provide separation in the same direction for all threats Bit Coding RA is preventive RA is corrective Upward sense RA has been generated Downward sense RA has been generated RA is not increased rate RA is increased rate 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 4-18 When ARA bit 41 = 0 and MTE = 1, bits 42-47 shall have the following meanings: Note.— When ARA bit 41 = 0 and MTE = 0, no vertical RA has been generated. 4.3.8.4.2.2.1.2 RAC (RACs record). This 4-bit (55-58) subfield shall indicate all the currently active RACs, if any, received from other ACAS aircraft. The bits in RAC shall have the following meanings: A bit set to 1 shall indicate that the associated RAC is active. A bit set to 0 shall indicate that the associated RAC is inactive. 4.3.8.4.2.2.1.3 RAT (RA terminated indicator). This 1-bit (59) subfield shall indicate when an RA previously generated by ACAS has ceased being generated. Note 1.— After an RA has been terminated by ACAS, it is still required to be reported by the Mode S transponder for 18±1 s (4.3.11.4.1). The RA terminated indicator may be used, for example, to permit timely removal of an RA indication from an air traffic controller’s display, or for assessments of RA duration within a particular airspace. Note 2.— RAs may terminate for a number of reasons: normally, when the conflict has been resolved and the threat is diverging in range; or when the threat’s Mode S transponder for some reason ceases to report altitude during the conflict. The RA terminated indicator is used to show that the RA has been removed in each of these cases. 4.3.8.4.2.2.1.4 MTE (multiple threat encounter). This 1-bit (60) subfield shall indicate whether two or more simultaneous threats are currently being processed by the ACAS threat resolution logic. RA is not a sense reversal RA is a sense reversal RA is not altitude crossing RA is altitude crossing RA is vertical speed limit RA is positive 48-54 Reserved for ACAS III Bit Coding RA does not require a correction in the upward sense RA requires a correction in the upward sense RA does not require a positive climb RA requires a positive climb RA does not require a correction in the downward sense RA requires a correction in the downward sense RA does not require a positive descend RA requires a positive descend RA does not require a crossing RA requires a crossing RA is not a sense reversal RA is a sense reversal 48-54 Reserved for ACAS III Bit Resolution advisory complement Do not pass below Do not pass above Do not turn left Do not turn right Coding ACAS is currently generating the RA indicated in the ARA subfield The RA indicated by the ARA subfield has been terminated (4.3.11.4.1) 2007/70/II. szám Chapter 4 Annex 10 — Aeronautical Telecommunications 4-19 28/11/02 4.3.8.4.2.2.1.5 TTI (threat type indicator subfield). This 2-bit subfield (61-62) shall define the type of identity data contained in the TID subfield. 4.3.8.4.2.2.1.6 TID (threat identity data subfield). This 26-bit subfield (63-88) shall contain the Mode S address of the threat or the altitude, range, and bearing if the threat is not Mode S equipped. If two or more threats are simultaneously processed by the ACAS resolution logic, TID shall contain the identity or position data for the most recently declared threat. If TTI = 1, TID shall contain in bits 63-86 the aircraft address of the threat, and bits 87 and 88 shall be set to 0. If TTI = 2, TID shall contain the following three subfields. 4.3.8.4.2.2.1.6.1 TIDA (threat identity data altitude subfield). This 13-bit subfield (63-75) shall contain the most recently reported Mode C altitude code of the threat. 4.3.8.4.2.2.1.6.2 TIDR (threat identity data range subfield). This 7-bit subfield (76-82) shall contain the most recent threat range estimated by ACAS. 4.3.8.4.2.2.1.6.3 TIDB (threat identity data bearing subfield). This 6-bit subfield (83-88) shall contain the most recent estimated bearing of the threat aircraft, relative to the ACAS aircraft heading. Note.— Structure of MB for an RA report: Coding One threat is being processed by the resolution logic (when ARA bit 41 = 1); or no threat is being processed by the resolution logic (when ARA bit 41 = 0) Two or more simultaneous threats are being processed by the resolution logic Coding No identity data in TID TID contains a Mode S transponder address TID contains altitude, range and bearing data Not assigned Coding Bit Mode C code bit C1 A1 C2 A2 C4 A4 B1 D1 B2 D2 B4 D4 Coding (n) n Estimated range (NM) No range estimate available Less than 0.05 2-126 (n-1)/10 ±0.05 Greater than 12.55 Coding (n) n Estimated bearing (degrees) No bearing estimate available 1-60 Between 6(n-1) and 6n 61-63 Not assigned BDS1 = 3 BDS2 = 0 ARA RAC RAT MTE TTI = 1 TID BDS1 = 3 BDS2 = 0 ARA RAC RAT MTE TTI = 2 TIDA TIDR TIDB 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 4-20 4.3.8.4.2.2.2 Subfields in MB for the data link capability report. When BDS1 = 1 and BDS2 = 0, the following bit patterns shall be provided to the transponder for its data link capability report: Note 1.— A summary of the MB subfields for the data link capability report structure is described in Chapter 3, 3.1.2.6.10.2.2. Note 2.— The use of hybrid surveillance to limit ACAS active interrogations is described in 4.5.1. The ability only to support decoding of DF = 17 extended squitter messages is not sufficient to set bit 72. 4.3.8.4.2.3 MU field. This 56-bit (33-88) field of long air-air surveillance interrogations (Figure 4-1) shall be used to transmit resolution messages, ACAS broadcasts and RA broadcasts. 4.3.8.4.2.3.1 UDS (U-definition subfield). This 8-bit (33-40) subfield shall define the remainder of MU. Note.— For convenience in coding, UDS is expressed in two groups of four bits each, UDS1 and UDS2. 4.3.8.4.2.3.2 Subfields in MU for a resolution message. When UDS1 = 3 and UDS2 = 0 the following subfields shall be contained in MU: 4.3.8.4.2.3.2.1 MTB (multiple threat bit). This 1-bit (42) subfield shall indicate the presence or absence of multiple threats. 4.3.8.4.2.3.2.2 VRC (vertical RAC). This 2-bit (45-46) subfield shall denote a vertical RAC relating to the addressed aircraft. 4.3.8.4.2.3.2.3 CVC (cancel vertical RAC). This 2-bit (43-44) subfield shall denote the cancellation of a vertical RAC previously sent to the addressed aircraft. This subfield shall be set to 0 for a new threat. 4.3.8.4.2.3.2.4 HRC (horizontal RAC). This 3-bit (50-52) subfield shall denote a horizontal RAC relating to the addressed aircraft. Bit Coding 0 ACAS failed or on standby 1 ACAS operating 0 ACAS II 1 ACAS III 0 ACAS generating TAs only 1 ACAS generating TAs and RAs 0 ACAS not fitted 1 ACAS fitted 0 Hybrid surveillance not fitted 1 Hybrid surveillance fitted Coding Interrogating ACAS has one threat Interrogating ACAS has more than one threat Coding No vertical RAC sent Do not pass below Do not pass above Not assigned Coding No cancellation Cancel previously sent “Do not pass below” Cancel previously sent “Do not pass above” Not assigned 2007/70/II. szám Chapter 4 Annex 10 — Aeronautical Telecommunications 4-21 28/11/02 4.3.8.4.2.3.2.5 CHC (cancel horizontal RAC). This 3-bit (47-49) subfield shall denote the cancellation of a horizontal RAC previously sent to the addressed aircraft. This subfield shall be set to 0 for a new threat. 4.3.8.4.2.3.2.6 VSB (vertical sense bits subfield). This 4-bit (61-64) subfield shall be used to protect the data in the CVC and VRC subfields. For each of the 16 possible combinations of bits 43-46 the following VSB code shall be transmitted: Note.— The rule used to generate the VSB subfield bit setting is a distance 3 Hamming code augmented with a parity bit, producing the ability to detect up to three errors in the eight transmitted bits. 4.3.8.4.2.3.2.7 HSB (horizontal sense bits subfield). This 5-bit (56-60) subfield shall be used to protect the data in the CHC and HRC subfields. For each of the 64 possible combinations of bits 47-52 the following HSB code shall be transmitted: Coding No horizontal RAC or no horizontal resolution capability Other ACAS sense is turn left; do not turn left Other ACAS sense is turn left; do not turn right Not assigned Not assigned Other ACAS sense is turn right; do not turn left Other ACAS sense is turn right; do not turn right Not assigned Coding No cancellation or no horizontal resolution capability Cancel previously sent “Do not turn left” Cancel previously sent “Do not turn right” 3-7 Not assigned CVC VRC VSB Coding 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 4-22 CHC HRC HSB Coding 2007/70/II. szám Chapter 4 Annex 10 — Aeronautical Telecommunications 4-23 28/11/02 Note.— The rule used to generate the HSB subfield bit setting is a distance 3 Hamming code augmented with a parity bit, producing the ability to detect up to three errors in the eleven transmitted bits. 4.3.8.4.2.3.2.8 MID (Aircraft address). This 24-bit (65-88) subfield shall contain the 24-bit aircraft address of the interrogating ACAS aircraft. Note.— Structure of MU for a resolution message: 4.3.8.4.2.3.3 Subfield in MU for an ACAS broadcast. When UDS1 = 3 and UDS2 = 2, the following subfield shall be contained in MU: 4.3.8.4.2.3.3.1 MID (Aircraft address). This 24-bit (65-88) subfield shall contain the 24-bit aircraft address of the interrogating ACAS aircraft. Note.— Structure of MU for an ACAS broadcast: 4.3.8.4.2.3.4 Subfields in MU for an RA broadcast. When UDS1 = 3 and UDS2 = 1, the following subfields shall be contained in MU: 4.3.8.4.2.3.4.1 ARA (active RAs). This 14-bit (41-54) subfield shall be coded as defined in 4.3.8.4.2.2.1.1. 4.3.8.4.2.3.4.2 RAC (RACs record). This 4-bit (55-58) subfield shall be coded as defined in 4.3.8.4.2.2.1.2. 4.3.8.4.2.3.4.3 RAT (RA terminated indicator). This 1-bit (59) subfield shall be coded as defined in 4.3.8.4.2.2.1.3. 4.3.8.4.2.3.4.4 MTE (multiple threat encounter). This 1-bit (60) subfield shall be coded as defined in 4.3.8.4.2.2.1.4. 4.3.8.4.2.3.4.5 AID (Mode A identity code). This 13-bit (63-75) subfield shall denote the Mode A identity code of the reporting aircraft. 4.3.8.4.2.3.4.6 CAC (Mode C altitude code). This 13-bit (76-88) subfield shall denote the Mode C altitude code of the reporting aircraft. UDS1 = 3 UDS2 = 0 -1- MTB CVC VRC CHC HRC -3- HSB VSB MID UDS1 = 3 UDS2 = 2 – – – – – 24 – – – – – MID Coding Bit Mode A code bit C1 A1 C2 A2 C4 A4 B1 D1 B2 D2 B4 D4 CHC HRC HSB Coding 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 4-24 Note.— Structure of MU for an RA broadcast: 4.3.8.4.2.4 MV field. This 56-bit (33-88) field of long air-air surveillance replies (Figure 4-1) shall be used to transmit air-air coordination reply messages. 4.3.8.4.2.4.1 VDS (V-definition subfield). This 8-bit (33-40) subfield shall define the remainder of MV. Note.— For convenience in coding, VDS is expressed in two groups of four bits each, VDS1 and VDS2. 4.3.8.4.2.4.2 Subfields in MV for a coordination reply. When VDS1 = 3 and VDS2 = 0, the following subfields shall be contained in MV: 4.3.8.4.2.4.2.1 ARA (active RAs). This 14-bit (41-54) subfield shall be coded as defined in 4.3.8.4.2.2.1.1. 4.3.8.4.2.4.2.2 RAC (RACs record). This 4-bit (55-58) subfield shall be coded as defined in 4.3.8.4.2.2.1.2. 4.3.8.4.2.4.2.3 RAT (RA terminated indicator). This 1-bit (59) subfield shall be coded as defined in 4.3.8.4.2.2.1.3. 4.3.8.4.2.4.2.4 MTE (multiple threat encounter). This 1-bit (60) subfield shall be coded as defined in 4.3.8.4.2.2.1.4. Note.— Structure of MV for a coordination reply: 4.3.8.4.2.5 SL (sensitivity level report). This 3-bit (9-11) downlink field shall be included in both short and long air-air reply formats (DF = 0 and 16). This field shall denote the sensitivity level at which ACAS is currently operating. 4.3.9 ACAS equipment characteristics 4.3.9.1 Interfaces. As a minimum, the following input data shall be provided to the ACAS:

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