Publication: Magyar Közlöny
Issue: MK-2007-70 (Year: 2007, Number: 70)
Era: 2004-2010
Section: Melléklet a 2007. évi XLVI. törvényhez
Paragraph Index: 4767

c) when the intruder is equipped and responds .12. horizontal separation vertical separation above FL100 2.0 NM 750 ft below FL100 1.2 NM 750 ft 2007/70/II. szám Chapter 4 Annex 10 — Aeronautical Telecommunications 4-41 28/11/02 4.4.4.3 DEVIATIONS CAUSED BY ACAS 4.4.4.3.1 Under the conditions of 4.4.2, the collision avoidance logic shall be such that the number of RAs resulting in “deviations” (4.4.4.3.2) greater than the values indicated shall not exceed the following proportions of the total number of RAs: 4.4.4.3.2 For the purposes of 4.4.4.3.1, the “deviation” of the equipped aircraft from the original trajectory shall be measured in the interval from the time at which the RA is first issued until the time at which, following cancellation of the RA, the equipped aircraft has recovered its original altitude rate. The deviation shall be calculated as the largest altitude difference at any time in this interval between the trajectory followed by the equipped aircraft when responding to its RA and its original trajectory. 4.4.5 Relative value of conflicting objectives Recommendation.— The collision avoidance logic should be such as to reduce as much as practicable the risk of collision (measured as defined in 4.4.3) and limit as much as practicable the disruption to ATM (measured as defined in 4.4.4). 4.5 ACAS USE OF EXTENDED SQUITTER REPORTS 4.5.1 ACAS hybrid surveillance using extended squitter position data Note.— Hybrid surveillance is the technique used by ACAS to take advantage of passive position information available via extended squitter. Using hybrid surveillance, ACAS validates the position provided by extended squitter through direct active range measurement. An initial validation is performed at track initiation. Revalidation is performed once per 10 seconds if the intruder becomes a near threat in altitude or range. Finally, regular active surveillance is performed once per second on intruders that become a near threat in both altitude and range. In this manner, passive surveillance (once validated) is used for non-threatening intruders thus lowering the ACAS interrogation rate. Active surveillance is used whenever an intruder becomes a near threat in order to preserve ACAS independence as an independent safety monitor. 4.5.1.1 DEFINITIONS Active surveillance. The process of tracking an intruder by using the information gained from the replies to own aircraft’s interrogations. when own aircraft’s vertical rate at the time the RA is first issued is less than 400 ft/min exceeds 400 ft/min when the intruder is not ACAS equipped, for deviations >300ft .15 .23 for deviations >600ft .04 .13 for deviations >1 000ft .01 .07 when the intruder is equipped but does not respond, for deviations >300ft .23 .35 for deviations >600ft .06 .16 for deviations >1 000ft .02 .07 when the intruder is equipped and responds, for deviations >300ft .11 .23 for deviations >600ft .02 .12 for deviations >1 000ft .01 .06 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 4-42 Active track. A track formed by measurements gained by active interrogation. Hybrid surveillance. The process of using active surveillance to validate and monitor other aircraft being tracked principally using passive surveillance in order to preserve ACAS independence. Initial acquisition. The process of starting the formation of a new track upon receipt of a squitter from a Mode S aircraft for which there is no track by making an active interrogation. Initial validation. The process of verifying the relative position of a new track using passive information by comparing it to the relative position obtained by active interrogation. Passive surveillance. The process of tracking another aircraft without interrogating it, by using the other aircraft’s extended squitters. ACAS uses the information contained in passive tracks to monitor the need for active surveillance, but not for any other purpose. Passive track. After initial acquisition, a track maintained without active interrogation, using information contained in extended squitters. 4.5.1.2 An ACAS equipped to receive extended squitter position reports for passive surveillance of non-threatening intruders shall utilize this passive position information in the following manner. 4.5.1.3 PASSIVE SURVEILLANCE 4.5.1.3.1 Initial validation. At initial acquisition of an aircraft reporting extended squitter information, ACAS shall determine the relative range and bearing as computed from the position of own aircraft and the intruder’s position as reported in the extended squitter. This derived range and bearing and the altitude reported in the squitter shall be compared to the range, bearing and altitude determined by active ACAS interrogation of the aircraft. Differences between the derived and measured range and bearing and the squitter and squitter and reply altitude shall be computed and used in tests to determine whether the extended squitter data is valid. If these tests are satisfied the passive position shall be considered to be validated and the track shall be maintained on passive data. If any of the above tests fail, the track shall be declared an active track and no further use shall be made of the subsequent passive surveillance data received for this track. 4.5.1.3.2 Recommendation.— The following tests should be used to validate the position reported in the extended squitter message: | slant range difference | < 200 m; and | bearing difference | < 45 degrees; and | altitude difference | < 100 ft. 4.5.1.3.3 Supplementary active interrogations. In order to ensure that an intruder’s track is updated at least as frequently as required in the absence of extended squitter data (4.3.7.1.2.2), each time a track is updated using squitter information the time at which an active interrogation would next be required shall be calculated. An active interrogation shall be made at that time if a further squitter has not been received before the interrogation is due. 4.5.1.4 Revalidation and monitoring. If the following condition is met for a track being updated using passive surveillance data:

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