Publication: Magyar Közlöny
Issue: MK-2007-70 (Year: 2007, Number: 70)
Era: 2004-2010
Section: Melléklet a 2007. évi XLVI. törvényhez
Paragraph Index: 4694

c) SLC command from Mode S ground stations. 4.3.4.3.1 Permitted SLC command codes. As a minimum, the acceptable SLC command codes shall include: 4.3.4.3.2 Altitude-band SLC command. Where ACAS selects an SLC command based on altitude, hysteresis shall be applied to the nominal altitude thresholds at which SLC command value changes are required as follows: for a climbing ACAS aircraft the SLC command shall be increased at the appropriate altitude threshold plus the hysteresis value; for a descending ACAS aircraft the SLC command shall be decreased at the appropriate altitude threshold minus the hysteresis value. 4.3.4.3.3 Pilot SLC command. For the SLC command set by the pilot the value 0 shall indicate the selection of the “automatic” mode for which the sensitivity level selection shall be based on the other commands. Table 4-2 Coding for SLC based on altitude band 2-7 for SLC from pilot input 0,1,2 for SLC from Mode S ground stations 0,2-6 Sensitivity level Nominal warning time no RAs 15s 20s 25s 30s 35s 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 4-10 4.3.4.3.4 Mode S ground station SLC command. For SLC commands transmitted via Mode S ground stations (4.3.8.4.2.1.1), the value 0 shall indicate that the station concerned is not issuing an SLC command and that sensitivity level selection shall be based on the other commands, including non-0 commands from other Mode S ground stations. ACAS shall not process an uplinked SLC value of 1. 4.3.4.3.4.1 ATS selection of SLC command code. ATS authorities shall ensure that procedures are in place to inform pilots of any ATS selected SLC command code other than 0 (4.3.4.3.1). 4.3.4.3.5 Selection rule. Own ACAS sensitivity level shall be set to the smallest non-0 SLC command received from any of the sources listed in 4.3.4.3. 4.3.4.4 Selection of parameter values for RA generation. When the sensitivity level of own ACAS is 3 or greater, the parameter values used for RA generation that depend on sensitivity level shall be based on the greater of the sensitivity level of own ACAS, So, and the sensitivity level of the intruder’s ACAS, Si. 4.3.4.5 Selection of parameter values for TA generation. The parameter values used for TA generation that depend on sensitivity level shall be selected on the same basis as those for RAs (4.3.4.4) except when an SLC command with a value of 2 (“TA only” mode) has been received from either the pilot or a Mode S ground station. In this case, the parameter values for TA generation shall retain the values they would have had in the absence of the SLC command from the pilot or Mode S ground station. 4.3.5 Resolution advisories (RAs) 4.3.5.1 RA generation. For all threats, ACAS shall generate an RA except where it is not possible to select an RA that can be predicted to provide adequate separation either because of uncertainty in the diagnosis of the intruder’s flight path or because there is a high risk that a manoeuvre by the threat will negate the RA. 4.3.5.1.1 RA cancellation. Once an RA has been generated against a threat or threats it shall be maintained or modified until tests that are less stringent than those for threat detection indicate on two consecutive cycles that the RA may be cancelled, at which time it shall be cancelled. 4.3.5.2 RA selection. ACAS shall generate the RA that is predicted to provide adequate separation from all threats and that has the least effect on the current flight path of the ACAS aircraft consistent with the other provisions in this chapter. 4.3.5.3 RA effectiveness. The RA shall not recommend or continue to recommend a manoeuvre or manoeuvre restriction that, considering the range of probable threat trajectories, is more likely to reduce separation than increase it, subject to the provisions in 4.3.5.5.1.1 and 4.3.5.6. Note.— See also 4.3.5.8. 4.3.5.4 Aircraft capability. The RA generated by ACAS shall be consistent with the performance capability of the aircraft. 4.3.5.4.1 Proximity to the ground. Descend RAs shall not be generated or maintained when own aircraft is below 300 m (1 000 ft) AGL. 4.3.5.4.2 ACAS shall not operate in sensitivity levels 3-7 when own aircraft is below 300 m (1 000 ft) AGL. 4.3.5.5 Reversals of sense. ACAS shall not reverse the sense of an RA from one cycle to the next, except as permitted in 4.3.5.5.1 to ensure coordination or when the predicted separation at closest approach for the existing sense is inadequate. 4.3.5.5.1 Sense reversals against equipped threats. If an RAC received from an equipped threat is incompatible with the current RA sense, ACAS shall modify the RA sense to conform with the received RAC if own aircraft address is higher in value than that of the threat. 2007/70/II. szám Chapter 4 Annex 10 — Aeronautical Telecommunications 4-11 28/11/02 Note.— 4.3.6.1.3 requires that the own ACAS RAC for the threat is also reversed. 4.3.5.5.1.1 ACAS shall not modify an RA sense in a way that makes it incompatible with an RAC received from an equipped threat if own aircraft address is higher in value than that of the threat. 4.3.5.6 RA strength retention. Subject to the requirement that a descend RA is not generated at low altitude (4.3.5.4.1), an RA shall not be modified if the time to closest approach is too short to achieve a significant response or if the threat is diverging in range. 4.3.5.7 Weakening an RA. An RA shall not be weakened if it is likely that it would subsequently need to be strengthened. 4.3.5.8 ACAS-equipped threats. The RA shall be compatible with all the RACs transmitted to threats (4.3.6.1.3). If an RAC is received from a threat before own ACAS generates an RAC for that threat, the RA generated shall be compatible with the RAC received unless such an RA is more likely to reduce separation than increase it and own aircraft address is lower in value than that of the threat. Note.— In encounters with more than one threat where it is necessary to pass above some threats and below other threats, this standard can be interpreted as referring to the whole duration of the RA. Specifically, it is permissible to retain an RA to climb (descend) towards a threat that is above (below) own aircraft provided there is a calculated intention to provide adequate separation from all threats by subsequently levelling-off. 4.3.5.9 Encoding of ARA subfield. On each cycle of an RA, the RA sense, strength and attributes shall be encoded in the active RA (ARA) subfield (4.3.8.4.2.2.1.1). If the ARA subfield has not been refreshed for an interval of 6 s, it shall be set to 0, along with the MTE subfield in the same message (4.3.8.4.2.2.1.3). 4.3.5.10 System response time. The system delay from receipt of the relevant SSR reply to presentation of an RA sense and strength to the pilot shall be as short as possible and shall not exceed 1.5 s. 4.3.6 Coordination and communication 4.3.6.1 PROVISIONS FOR COORDINATION WITH ACAS-EQUIPPED THREATS 4.3.6.1.1 Multi-aircraft coordination. In a multi-aircraft situation, ACAS shall coordinate with each equipped threat individually. 4.3.6.1.2 Data protection during coordination. ACAS shall prevent simultaneous access to stored data by concurrent processes, in particular, during resolution message processing. 4.3.6.1.3 Coordination interrogation. Each cycle ACAS shall transmit a coordination interrogation to each equipped threat, unless generation of an RA is delayed because it is not possible to select an RA that can be predicted to provide adequate separation (4.3.5.1). The resolution message transmitted to a threat shall include an RAC selected for that threat. If an RAC has been received from the threat before ACAS selects an RAC for that threat, the selected RAC shall be compatible with the received RAC unless no more than three cycles have elapsed since the RAC was received, the RAC is altitude-crossing, and own aircraft address is lower in value than that of the threat in which case ACAS shall select its RA independently. If an RAC received from an equipped threat is incompatible with the RAC own ACAS has selected for that threat, ACAS shall modify the selected RAC to be compatible with the received RAC if own aircraft address is higher in value than that of the threat. Note.— The RAC included in the resolution message is in the form of a vertical RAC (VRC) for ACAS II (4.3.8.4.2.3.2.2) and a vertical RAC (VRC) and/or horizontal RAC (HRC) for ACAS III. 4.3.6.1.3.1 Coordination termination. Within the cycle during which an intruder ceases to be a reason for maintaining the RA, ACAS shall send a resolution message to that intruder by means of a coordination interrogation. The resolution message shall include the cancellation code for the last RAC sent to that intruder while it was a reason for maintaining the RA. 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 4-12 Note.— During an encounter with a single threat, the threat ceases to be a reason for the RA when the conditions for cancelling the RA are met. During an encounter with multiple threats, a threat ceases to be a reason for the RA when the conditions for cancelling the RA are met in respect of that threat, even though the RA may have to be maintained because of other threats. 4.3.6.1.3.2 ACAS coordination interrogations shall be transmitted until a coordination reply is received from the threat, up to a maximum of not less than six and not more than twelve attempts. The successive interrogations shall be nominally equally spaced over a period of 100 ±5 ms. If the maximum number of attempts is made and no reply is received, ACAS shall continue its regular processing sequence. 4.3.6.1.3.3 ACAS shall provide parity protection (4.3.8.4.2.3.2.6 and 4.3.8.4.2.3.2.7) for all fields in the coordination interrogation that convey RAC information. Note.— This includes the vertical RAC (VRC), the cancel vertical RAC (CVC), the horizontal RAC (HRC) and the cancel horizontal RAC (CHC). 4.3.6.1.3.4 Whenever own ACAS reverses its sense against an equipped threat, the resolution message that is sent on the current and subsequent cycles to that threat shall contain both the newly selected RAC and the cancellation code for the RAC sent before the reversal. 4.3.6.1.3.5 When a vertical RA is selected, the vertical RAC (VRC) (4.3.8.4.2.3.2.2) that own ACAS includes in a resolution message to the threat shall be as follows:

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