Publication: Magyar Közlöny
Issue: MK-2007-70 (Year: 2007, Number: 70)
Era: 2004-2010
Section: Melléklet a 2007. évi XLVI. törvényhez
Paragraph Index: 4905

c) the other aircraft is equipped with an ACAS having a collision avoidance logic identical to that of own ACAS. 6.2.7.2 The first circumstance a) ensures that the logic performs satisfactorily in encounters with an unequipped intruder. The other two circumstances both test the collision avoidance logic when the other aircraft is equipped but do so from different perspectives. Circumstance b) ensures that the logic performs satisfactorily under the constraints of the coordination process, while circumstance c) ensures that the benefits to be expected when both aircraft are equipped are realized. 6.2.7.3 The conditions applying in circumstance b) are intended to allow own ACAS to select its initial RA but to then apply the most pessimistic reasonable assumptions about the effect of the need for coordination on the performance of the own ACAS logic. When own aircraft has the lower aircraft address, the conditions of the test imply that the sense of the RA cannot be reversed. Furthermore, the intruder does not generate an RA and an RAC until the own ACAS RA is announced because an early design included an initial coordination delay (the purpose of which was to allow the coordination to complete and avoid the pilot seeing rapid changes in the RA); the intention of the requirement is to ensure that performance is satisfactory in spite of the deleterious effects of any such delay. 6.2.7.4 Circumstance c) requires that the behaviour of the two aircraft be fully cooperative, but the fact that both ACAS are using the subject logic ensures that the performance measure relates to the subject logic and that the subject logic is effective. 6.2.7.5 As discussed above, the performance specifications are intended to ensure satisfactory operation of the logic and not the system as a whole. To the extent that they are capable of wider interpretation in terms of the benefits of the system as a whole in an operational environment, circumstance c) might be thought to provide the more credible performance measure for ACAS-ACAS encounters. The specified performance of the logic in circumstance b) is worse than that where the intruder is not equipped, because circumstance b) invokes only the constraints imposed by coordination. However, the fact that the cooperation of an intruder cannot be guaranteed and that some pilots will fail to respond to RAs on occasion means that all three measures have operational relevance. 6.3 Reduction in the risk of collision 6.3.1 STATUS OF THE LOGIC RISK RATIO 6.3.1.1 The risk ratio calculated for the purposes of Chapter 4, 4.4.3 is a measure of the performance of the logic and not the ACAS as a whole. For example, ACAS can prevent a collision by prompting the pilot to carry out a successful visual search for the intruder and it can fail because a track is not established or the pilot ignores the RA; these are aspects of the total system that are not reflected in the calculations required for Chapter 4, 4.4.3. 6.3.1.2 When considering the relevance of the “logic risk ratio” figures calculated for Chapter 4, 4.4.3 to operations or policy decisions, it might be helpful to regard them as solely the reliability that can be attached to RAs. They express the effect that following an RA will have on the immediate risk of collision when, at the time it is issued, the pilot has no information other than the RA on which to base a decision whether to follow the RA or ignore it. As a rough guide, the collision risk created by ACAS arises from following the RA so the logic risk ratio overstates this “induced risk ratio”; on the other hand, it also overstates the capability of ACAS to prevent collisions because of the many other failure modes in the total system. 6.3.1.3 The figures calculated for the purposes of Chapter 4, 4.4.3 are unsuitable as guidance concerning the effect of ACAS on the overall risk of collision in an airspace or faced by an airline. 6.3.2 CALCULATION OF THE LOGIC RISK RATIO 6.3.2.1 The risk ratio R can be written: where the summation is over all encounters, or, more practically, all encounters that contribute to the total risk of collision with or without ACAS. The need for the R = ∑ probability of a collision with ACAS ∑ probability of a collision without ACAS 2007/70/II. szám Attachment Annex 10 — Aeronautical Telecommunications ATT-55 28/11/02 characteristics and statistics of the encounters to be representative of operational realities is standardized in Chapter 4, 4.4.2.6 and discussed in 6.2.6. 6.3.2.2 The estimated risk of collision depends on the interpretation of the word “collision”. While this problem is largely avoided by expressing the requirement in terms of the ratio between the risks of collision with and without ACAS, it is important that realistic allowance is made for the size of the largest aircraft. It would be reasonable to treat a vertical separation of less than 100 ft between the centre points of the two aircraft as if it were small enough to allow a collision. It would not be advisable to use significantly larger miss distances as approximations to collisions because it has been found that the calculated risk ratio is sensitive to the definition of “collision” even though it is a ratio. 6.3.2.3 If the approximation is made that a collision occurs when |d| < 100 ft, where d is the actual vertical separation where now the summation is over all encounters with zero or extremely small horizontal miss distance. 6.3.2.4 Now introduce e, the altimeter error and a, the apparent vertical separation and note that a = d + e a is conceptually the altitude separation as measured by altimeters. It should not be necessary to consider quantization errors because the modelled altimeter readings can be known with arbitrary precision in the computer simulations. They are quantized before they are provided to ACAS as modelled Mode C reports, which ACAS tracks. This is why the standard Chapter 4, 4.4.2 excludes quantization effects. 6.3.2.5 Define awith to be the apparent vertical separation with ACAS and awithout to be the apparent vertical separation without ACAS. Then |d| < 100 ft with ACAS if and only if |awith –e|<100 ft i.e. awith –100 ft < e < awith + 100 ft and similarly |d| <100 ft without ACAS if and only if |awithout –100 ft < e < awithout + 100 ft 6.3.2.6 Risk ratio is thus given by In order to use this formula to calculate risk ratio, the values of awith and awithout must be determined for a collection of encounters that is fully representative of all the potential actual encounters in which there is both a risk of collision without ACAS and a risk that ACAS will induce a collision. When these values of hypothetically measured altitude separation are known, knowledge of the errors in altitude measurement completes the calculation. 6.3.3 INDUCED AND UNRESOLVED RISK 6.3.3.1 It is not sufficient to demonstrate that ACAS will prevent collisions that might occur in its absence. The risk that ACAS logic could cause collisions in otherwise safe circumstances must be fully considered, not least because in managed airspace the number of encounters potentially facing an induced risk greatly exceeds the number of near collisions. 6.3.3.2 The upper limit on the logic risk ratio standardized at Chapter 4, 4.4.3 effectively places an approximate upper limit on the ACAS induced risk of collision. Although some other failures could cause ACAS to induce a collision, e.g. pilots manoeuvring on a TA or an RA directing the aircraft into the trajectory of an unseen third party, the induced risk is largely attributable to following RAs. In operational conditions, failure to raise or follow an RA will reduce the risk of an induced collision (even though it increases the absolute risk). 6.3.3.3 The requirement is that the logic is designed to reduce the risk of collision and no distinction is drawn between risk induced by the logic and risk that it is unable to resolve. It is possible to draw such a distinction and even to subdivide the risk into that due to altimeter error and that due to inappropriate operation of the logic but it is considered that this exercise has little value for the design of the logic. 6.3.4 USE OF GROUND RADAR DATA TO CALCULATE RISK RATIO It is possible to use encounters observed in ground radar data as the basis of the safety calculations described in 6.3.2. However, it is difficult to interpret the results because the calculation concerns extremely rare events and, even when many months of data are used, trajectories have to be modified to insert a risk of collision that was absent in the actual encounters. It is more practicable to use the radar data to inform the choice of the weights to be ascribed to the various encounter classes in the encounter model and thus produce a Then R = ∑ prob(|d| < 100 ft with ACAS) ∑ prob(|d| < 100 ft without ACAS) R = ∑prob(awith –100 ft < e < awith + 100 ft) ∑prob(awithout –100 ft < e < awithout + 100 ft) 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 ATT-56 version of the idealized encounter model that is more representative of the airspace in question than the standard model presented here. 6.4 Compatibility with ATM 6.4.1 NUISANCE ALERT RATE 6.4.1.1 ACAS is required to diagnose a risk of imminent collision on the basis of incomplete information. Furthermore, this information has to be independent of that providing the primary basis for aircraft separation. It follows that there will be alerts in encounters where, from an operational perspective, there would seem to be no risk of collision. Standard Chapter 4, 4.4.4.1 requires that these nuisance alerts be as infrequent as possible. 6.4.1.2 The specification of a nuisance RA given in Chapter 4, 4.4.4.1.2 is made with the view that an RA is a nuisance if normal standard separation is not clearly lost. Additionally, it is intended that the horizontal separation threshold is sufficiently stringent to require the use of a horizontal miss distance filter. The horizontal separation threshold has been set at 40 per cent of normal separation, and the vertical separation threshold has been set at a figure based on an ATC tolerance of deviations of 200 ft from altitude clearance. 6.4.2 COMPATIBLE SENSE SELECTION The requirement at Chapter 4, 4.4.4.2 is not intended to constrain the manner in which dangerous encounters are resolved, but rather is based on an appreciation that the majority of RAs are likely to be generated in encounters where there is no danger of collision. It places a statistical limit on the frequency with which ACAS disrupts ATC or the normal operation of the aircraft by inverting the vertical separation of two aircraft. 6.4.3 DEVIATIONS CAUSED BY ACAS The restrictions on the deviations that may be caused by following RAs, Chapter 4, 4.4.4.3, limit the disruption to normal aircraft operation as well as to ATC. While deviations from altitude clearances are the most obviously disruptive to ATC, other deviations, such as that caused by an RA to climb when the aircraft is descending, could be viewed equally seriously by ATC. 6.4.4 USE OF GROUND RADAR DATA OR THE STANDARD ENCOUNTER MODEL 6.4.4.1 Conformance with the requirement for compatibility with ATM can be tested most convincingly using simulations based on reconstructions of actual operational encounters occurring within the coverage of ATC ground radars, provided that only a small proportion of the aircraft thus observed are equipped with ACAS. However, the results of such simulations based on actual data will reflect the particular properties of the airspace (or airspaces) in which the data were collected as much as those of the collision avoidance logic used. Thus, there are considerable practical difficulties in using real encounter data to validate collision avoidance logic, and the provisions of Chapter 4, 4.4.4 assume the use of artificial encounters based on the standard encounter model specified in Chapter 4, 4.4.2.6. 6.4.4.2 The use of the standard encounter model to obtain performance measures describing the operation of the collision avoidance logic will provide only indirect evidence concerning its operation in any particular airspace. Authorities that have access to ground radar data and wish to understand the interaction of ACAS with local ATC practices are advised to use simulations based on their ground radar data rather than the standard encounter model. In doing so, they need to note that the results can be subverted if the aircraft observed are already equipped with ACAS. They will also need to collect sufficient data to ensure that the simulated RAs derived from the data are statistically representative; for example, data collected over 100 days in one State contained very few examples of some types of RAs. 6.5 Relative value of conflicting objectives The design of the collision avoidance logic for ACAS must strike an operationally acceptable balance between the reduction in the risk of collision and the disruption caused by ACAS alerts. The requirements relating to the risk of collision (Chapter 4, 4.4.3) and the disruption to ATC (Chapter 4, 4.4.4) are minimum standards that are known to be achievable from work with a prototype system. Other designs are only acceptable when it can be demonstrated that the risk of collision and the disruption to ATC have both been minimized as much as practicable in the context of a need to minimize the other. — END — 2007/70/II. szám Aeronautical Telecommunications Annex 10 to the Convention on International Civil Aviation International Civil Aviation Organization International Standards and Recommended Practices Second Edition July 2001 Volume V Aeronautical Radio Frequency Spectrum Utilization This edition incorporates all amendments adopted by the Council prior to 13 March 2001 and supersedes, on 1 November 2001, all previous editions of Annex 10, Volume V. For information regarding the applicability of the Standards and Recommended Practices, see Foreword. 2007/70/II. szám  	                              		 	 	                       	                2007/70/II. szám ANNEX 10 — VOLUME V (iii) 1/11/01 TABLE OF CONTENTS Page Page (v) CHAPTER 1. 1-1 CHAPTER 2. 2-1 2.1 Frequencies for emergency locator transmitters (ELTs) for search and rescue 2-1 2-1 CHAPTER 3. Utilization of frequencies below 3-1 3-1 3-2 CHAPTER 4. Utilization of frequencies above 4-1 4.1 Utilization in the band 4-1 4.2 Utilization in the band 4-7 4.3 Utilization in the band 960 – 1 215 MHz 4-9 4.4 Utilization in the band 4-10 APPENDIX to Chapter 4. List of assignable 4-11 ATTACHMENTS ATTACHMENT A. Considerations affecting the deployment of VHF communication 1. Criteria employed in establishing geographical separation between ground stations for co-channel operation of VHF facilities that have 2. Criteria employed in establishing adjacent channel frequency deployment with respect to receiver rejection and 3. Criteria to be employed in establishing adjacent channel frequency deployment of VHF facilities that have a service 4. Criteria to be employed in establishing geographical separation between ground stations and between aircraft and ground stations for co-channel operation of VHF facilities that have a service area 5. Criteria employed in establishing co-channel frequency deployment of 6. Criteria employed in establishing adjacent channel frequency deployment 7. RF — Characteristics for digital VHF systems, interference immunity ATTACHMENT B. Considerations affecting the deployment of LF/MF frequencies and the ATTACHMENT C. Guiding principles for long distance operational control 2007/70/II. szám ANNEX 10 — VOLUME V (v) 1/11/01 FOREWORD Historical background Standards and Recommended Practices for Aeronautical Telecommunications were first adopted by the Council on 30 May 1949 pursuant to the provisions of Article 37 of the Convention on International Civil Aviation (Chicago 1944) and designated as Annex 10 to the Convention. They became effective on 1 March 1950. The Standards and Recommended Practices were based on recommendations of the Communications Division at its Third Session in January 1949. Up to and including the Seventh Edition, Annex 10 was published in one volume containing four parts together with associated attachments: Part I — Equipment and Systems, Part II — Radio Frequencies, Part III — Procedures, and Part IV — Codes and Abbreviations. By Amendment 42, Part IV was deleted from the Annex; the codes and abbreviations contained in that part were transferred to a new document, Doc 8400. As a result of the adoption of Amendment 44 on 31 May 1965, the Seventh Edition of Annex 10 was replaced by two volumes: Volume I (First Edition) containing Part I — Equipment and Systems, and Part II — Radio Frequencies, and Volume II (First Edition) containing Communication Procedures. As a result of the adoption of Amendment 70 on 20 March 1995, Annex 10 was restructured to include five volumes: Volume I — Radio Navigation Aids; Volume II — Communication Procedures; Volume III — Communication Systems; Volume IV — Surveillance Radar and Collision Avoidance Systems; and Volume V — Aeronautical Radio Frequency Spectrum Utilization. By Amendment 70, Volumes III and IV were published in 1995 and Volume V was published in 1996 with Amendment 71. Table A shows the origin of amendments to Annex 10, Volume V subsequent to Amendment 71, together with a summary of the principal subjects involved and the dates on which the Annex and the amendments were adopted by Council, when they became effective and when they became applicable. Action by Contracting States Notification of differences. The attention of Contracting States is drawn to the obligation imposed by Article 38 of the Convention by which Contracting States are required to notify the Organization of any differences between their national regulations and practices and the International Standards contained in this Annex and any amendments thereto. Contracting States are invited to extend such notification to any differences from the Recommended Practices contained in this Annex and any amendments thereto, when the notification of such differences is important for the safety of air navigation. Further, Contracting States are invited to keep the Organization currently informed of any differences which may subsequently occur, or of the withdrawal of any differences previously notified. A specific request for notification of differences will be sent to Contracting States immediately after the adoption of each amendment to this Annex. The attention of States is also drawn to the provisions of Annex 15 related to the publication of differences between their national regulations and practices and the related ICAO Standards and Recommended Practices through the Aeronautical Information Service, in addition to the obligation of States under Article 38 of the Convention. Promulgation of information. The establishment and withdrawal of and changes to facilities, services and procedures affecting aircraft operations provided in accordance with the Standards, Recommended Practices and Procedures specified in Annex 10 should be notified and take effect in accordance with the provisions of Annex 15. Use of the text of the Annex in national regulations. The Council, on 13 April 1948, adopted a resolution inviting the attention of Contracting States to the desirability of using in their own national regulations, as far as practicable, the precise language of those ICAO Standards that are of a regulatory character and also of indicating departures from the Standards, including any additional national regulations that were important for the safety or regularity of air navigation. Wherever possible, the provisions of this Annex have been deliberately written in such a way as would facilitate incorporation, without major textual changes, into national legislation. Status of Annex components An Annex is made up of the following component parts, not all of which, however, are necessarily found in every Annex; they have the status indicated: 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume V 1/11/01 (vi) 1.— Material comprising the Annex proper:

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