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EUR Doc 040 EUROPEAN GUIDANCE MATERIAL ON MANAGEMENT OF ILS CRITICAL AND SENSITIVE AREAS First Edition June 2020 Approved by Correspondance by the EASPG September 2020 The designations and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of ICAO concerning the legal status of any country, territory, city or area of its authorities, or concerning the delimitation of its frontiers or boundaries. EUROPEAN AND NORTH ATLANTIC OFFICE OF ICAO International Civil Aviation Organization (ICAO) European and North Atlantic (EUR/NAT) Office 3 bis, Villa Emile Bergerat 92522, Neuilly-sur-Seine CEDEX FRANCE e-mail : [email protected] Tel : +33 1 46 41 85 85 Fax : +33 1 46 41 85 00 Web : http://www.icao.int/EURNAT  i Preamble Introduction 1. ICAO Annex 10 to the Convention on International Civil Aviation, Volume I (incorporating amendment 91, change 1, 7th Edition, July 2018) contains the requirements for ILS ground systems and guidance material on critical and sensitive areas. In this document the term “ICAO Annex 10, Volume I” will refer to this version of the Annex 10 provisions. 2. In order to safeguard the Instrument Landing System (ILS) signal-in-space, service providers have to establish and protect critical and sensitive areas. Infringement of these areas may cause an undetected out-of-tolerance signal or a shutdown of the ILS. This affects the integrity or continuity of service performance of the ILS. 3. Nothing in this Guidance Material should be construed as contradicting or conflicting with ICAO Standards and Recommended Practices and Procedures contained in the Annexes and PANS. European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  ii Table of Contents Table of Contents ............................................................................................................................... ii Record of Amendments ...................................................................................................................... iii CHAPTER 1 - About This Guidance Material........................................................................................ 1 1.1 Purpose and Scope...................................................................................................................... 1 CHAPTER 2 - GENERALLY APPLICABLE PRACTICES ................................................................ 2 2.1 General principle ........................................................................................................................ 2 2.2 Establishing ILS critical and sensitive areas .............................................................................. 2 2.3 Protection of ILS critical and sensitive areas ............................................................................. 2 2.4 Protection of localizer critical and sensitive areas ...................................................................... 3 2.5 Vertical dimensions of localizer critical and sensitive areas ...................................................... 3 2.6 Protection of glide path critical and sensitive areas.................................................................... 3 2.7 Vertical dimensions of the glide path critical and sensitive areas .............................................. 4 2.8 Air Traffic Controller awareness ................................................................................................ 4 CHAPTER 3 - PRACTICES FOR OPTIMIZING RUNWAY CAPACITY .......................................... 5 3.1 Specific operational practices ..................................................................................................... 5 3.2 Effects of infringements of critical and sensitive areas .............................................................. 5 3.3 Establishing the localizer critical and sensitive areas ................................................................. 6 3.4 Protection of localizer critical and sensitive areas...................................................................... 6 3.5 Dynamic management of localizer critical and sensitive areas as used for different categories of aircraft and operation....................................................................................................................... 9 3.6 Management of glide path critical and sensitive areas ............................................................... 9 APPENDIX A – Marking of critical and sensitive areas ...................................................................... 11 APPENDIX B – Display of critical and sensitive areas ........................................................................ 13 APPENDIX C – Examples of LOC deviations and aircraft reaction .................................................... 14 European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  iii RECORD OF AMENDMENTS EUROPEAN GUIDANCE MATERIAL ON MANAGEMENT OF ILS CRITICAL AND SENSITIVE AREAS This chart provides records of changes to edition 1.0 and onward editions. Paragraph(s) Explanation 1st edition As a result of the work from the All Weather Operations Group (supported by Mr Oguzhan Hasdeniz) of the former European Air Navigation Planning Group, the first edition of the EUR Doc was finalized in June 2020 and endorsed by the EASPG via correspondence in September 2020. European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  iv DEFINITIONS Note. — Definitions of terms which are not self-explanatory in that they do not have accepted dictionary meanings are presented below. A definition does not have an independent status but is an essential part of the paragraph of the Guidance Material in which the term is used, since a change in the meaning of the term would affect the provision. Note. — Most of the definitions and terms used throughout this Guidance Material are taken from the relevant ICAO Annexes, PANS and Manuals (reference to ICAO Docs is indicated in brackets for each term). However, one term has been defined specifically for this EUR Document and this is indicated by an “*”. When the following terms are used in this Guidance Material, they have the following meaning: Continuity of Service (Annex 10, Vol I, para 3.1.3.12 and 3.1.5.8) - The probability of not losing the radiated guidance signal. Critical Area (Annex 10, Vol I, App C para 2.1.9.2) - ILS critical and sensitive areas. States differ in the way they choose to identify ILS protection areas. Practices also differ in how vehicle movement restrictions are managed. One method is to identify critical areas and sensitive areas as follows: a) the ILS critical area is an area of defined dimensions about the localizer and glide path antennas where vehicles, including aircraft, are excluded during all ILS operations. The critical area is protected because the presence of vehicles and/or aircraft inside its boundaries will cause unacceptable disturbance to the ILS signal-in-space; b) the ILS sensitive area is an area where the parking and/or movement of vehicles, including aircraft, is controlled to prevent the possibility of unacceptable interference to the ILS signal during ILS operations. The sensitive area is protected against interference caused by large moving objects outside the critical area but still normally within the airfield boundary. Note 1.— In some States, the term “critical area” is used to describe an area that combines the critical and sensitive areas identified in this guidance material. In cases where the critical area overlaps operational areas, specific operational management procedures are required to ensure protection of aircraft using the ILS for intercept and final approach guidance. Note 2.— It is expected that at sites, where ILS and MLS are to be collocated, the MLS might be located within ILS critical areas in accordance with guidance material in Annex 10, Vol I, Attachment G, 4.1 ILS operation * - ILS operation is the use of ILS signals by one or more aircraft within the defined coverage volume. Integrity (Annex 10, Vol I, para 3.1.3.12 and 3.1.5.8) -- The probability of not radiating false guidance signals. Sensitive Area (Annex 10, Vol I, App C para 2.1.9.2) – see critical area above. European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  v Acronyms/Abbreviations The acronyms/abbreviations used in this document have the following meanings: ANSP Air Navigation Service Provider AIP Aeronautical Information Publication A-SMGCS Advanced Surface Movement Guidance and Control System ATC Air Traffic Control CAT Category CDI Course Deviation Indicator CSA Critical and Sensitive Areas DDM Difference in Depth of Modulation FAP Final Approach Point ILS Instrument Landing System LOC Localizer GP Glide Path LVP Low Visibility Procedures MLS Microwave Landing System MSA Minimum Sector Altitude PANS Procedures for Air Navigation Services PFD Primary Flight Display SARPS Standards and Recommended Practices TWY Taxiway ____________ European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 1 CHAPTER 1 - ABOUT THIS GUIDANCE MATERIAL 1.1 Purpose and Scope 1.1.1 This document provides guidance on the operational management of the Instrument Landing System (ILS) critical and sensitive areas by Air Traffic Control (ATC) staff and Air Navigation Service Provider (ANSP) engineering personnel. 1.1.2 It is not defining the ILS critical and sensitive areas, nor providing elements to compute their dimensions. Guidance material on how to define critical and sensitive areas has been generated by the ICAO Navigation System Panel. These elements, based on technical assessment, can be found in ICAO Annex 10, Vol I. 1.1.3 For each ILS installation, the engineering service of the service provider (supported by the system manufacturer and other appropriate staff) establishes the dimensions of critical and sensitive areas. Some of the analysis choices made in this assessment may have an impact on how the areas are managed (see ICAO Annex 10, Vol I, Attachment C para 2.1.9.3 and para 2.1.9.4). Keeping these areas free from obstacles and moving objects ensures that the required quality of the ILS signal in space is maintained. 1.1.4 However, because it is normally not possible to keep these areas completely free from infringements, it is necessary to manage such infringements to achieve an acceptable balance between optimizing runway capacity and ensuring the safety of aircraft using the ILS signal in space. 1.1.5 This document is also considering the vertical dimensions when proposing guidance on the management of ILS critical and sensitive areas, consistently with ICAO EUR Doc 013, European Guidance Material on All Weather Operations at Aerodromes (5th Edition, September 2016). 1.1.6 Autoland operations when Low Visibility Procedures (LVP) are not in operation are not covered in this document. Respective guidance is provided in the ICAO EUR Doc 013, European Guidance Material on All Weather Operations at Aerodromes (5th Edition, September 2016) and in ICAO Doc 9365, Manual of All Weather Operations (4th Edition, 2017) European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 2 CHAPTER 2 - GENERALLY APPLICABLE PRACTICES 2.1 General principle 2.1.1 This chapter is describing operational practices which may be put in place in order to protect the ILS guidance signals as standardized by ICAO Annex 10, Vol I. These practices are ensuring the full protection of the critical and sensitive areas as defined in the Attachment C of ICAO Annex 10, Vol I, and do not require SARPS deviation notifications from States. However, the application of these practices may lead to reduced runway capacity when the ILS is being used. 2.2 Establishing ILS critical and sensitive areas 2.2.1 The ILS critical and sensitive areas are established and protected by the responsible service provider by using guidance provided in ICAO Annex 10, Vol I, recommendations from the respective ILS manufacturer and through site specific studies. On major European airports with high traffic density, simulations and measurements were used to verify and fine tune the dimensions of the ILS critical and sensitive areas to minimize the dimensions while maintaining the airport capacity and safety. Note: A site specific analysis may identify that it can be assumed that the aircraft remains on runway centreline until it starts the turn to exit the runway and therefore that no out-of-tolerance signals are to be expected before the turn starts. Therefore the dimensions of critical and sensitive areas could be reduced compared to the typical figures presented in ICAO Annex 10, Vol I, i.e. shortened to the beginning of the next runway exit in the direction to the localizer. Example: The x-dimension of the critical area in ICAO Annex 10, Vol I, typical figures for A380 operation is 675 m. The localizer is located 320 m to the stop end of the runway which leads to 355 m critical area on the runway. Only the last runway exit is affected. The turn to this exit starts 140 m before stop end of the runway. Measurements and simulations made as part of the site specific analysis have indicated that no influence on the signal occurs while the aircraft is on centreline and aligned with the runway. Therefore in this example the size of the critical area could be shortened to 460 m which is of particular importance when the duration of critical area infringements has to be considered. 2.3 Protection of ILS critical and sensitive areas 2.3.1 Based on ICAO definition of critical area, one practice is to prohibit aircraft and vehicles within the ILS critical area during all ILS operations. In some States, the entrance of persons into the critical area is also restricted as it may impact the continuity of service. 2.3.2 At many airports, critical and sensitive areas which remain outside of runways and taxiways are marked by signs and other visual indicators in order to provide deterrent and visual warning that there is to be no unauthorized access to this area. To protect localizer signal-in-space from ground vehicles and persons, the elements in ICAO Annex 10, Vol I, are containing area dimensions typical figures established for large ground vehicles. Examples of markings are provided in Appendix A. 2.3.3 However, when the critical and sensitive areas overlap operational areas, management procedures have to be established for instance through the use of runway-holding positions as stated in ICAO Annex 14, Volume I, 8th Edition, July 2018. European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 3 2.4 Protection of localizer critical and sensitive areas 2.4.1 At some runways, the critical area may overlap the stop end and taxiways of the runway. The sensitive area will often overlap at least the stop end of the runway and possibly other adjoining taxiways. 2.4.2 If the localizer critical area overlaps the stop end and taxiways of the runway, in case aircraft exit the runway at the last possible exits near the stop end of the runway, any potential use of the ILS should be aborted until the critical area has been vacated again. 2.4.3 With respect to the protection of the localizer sensitive area in LVP, it is commonly accepted that the sensitive area has to be clear at least when the next arriving aircraft is within 2 NM before threshold provided that radar monitoring is available. In some States, reference is made to the touchdown instead of threshold. In current operations, landing clearance may exceptionally be delayed until 1 NM from touchdown, provided that flight crews are warned to expect a late landing clearance and also provided that the position of the approaching aircraft can be monitored (from ICAO EUR Doc 013, European Guidance Material on All Weather Operations at Aerodromes, 5th Edition, September 2016). To enable this practice, the sensitive area must be computed to protect operations below the 1 NM corresponding heights. 2.4.4 Considering the technical consequences of infringements of the localizer critical area (out- of-tolerance-signal), the general rule should be that also in CAT I operations, the CAT I localizer critical area should be free of aircraft and vehicles during ILS operations. 2.4.5 The same applies for the CAT I sensitive area when an arriving aircraft is within the last 2 NM before threshold until decision height (i.e. 0.6 NM before threshold) on a 3 degrees glide path (corresponding to the CAT I Decision Height). With respect to the localizer sensitive area in CAT I operations, it should be noted that in most cases, this area, which is much smaller than the sensitive areas for CAT II/III, may be covered by the runway protection surfaces (Obstacle Limitation Surfaces). Some States, therefore, do not define or protect a CAT I sensitive area in the same way as for CAT II/III. 2.5 Vertical dimensions of localizer critical and sensitive areas 2.5.1 The vertical dimensions of the localizer critical and sensitive areas are qualitatively introduced in ICAO Annex 10, Vol I, but are not quantified through typical figures. They cannot be ignored as the impact of an aircraft will not cease as soon as it becomes airborne. 2.5.2 The vertical dimension of the localizer critical and sensitive areas is particularly important when nearby runways operations are conducted or on a mixed departing-arriving runway. In the first case, aircraft operating on nearby runway may degrade the ILS localizer used during landing or guided take off. In the second case, a departing aircraft may degrade the localizer signal-in-space before overflying this localizer. In both cases, these potential effects are similar to an infringement of the critical and sensitive areas by taxiing aircraft. 2.5.3 At least one service provider is managing the nearby (parallel in that specific case) runway operations by requesting a minimum distance to threshold (e.g. 1 NM) for an approaching aircraft while the parallel departure has not reached the location of the arrival runway localizer. 2.5.4 For mixed arrival-departure runway operation, several Air Navigation Service Providers are already requiring a minimum distance to threshold (e.g. 2 NM) for an approaching aircraft while the departing aircraft has not overflown the radiating localizer as indicated in the ICAO EUR Doc 013, European Guidance Material on All Weather Operations at Aerodromes, 5th Edition, September 2016. 2.6 Protection of glide path critical and sensitive areas 2.6.1 Glide path critical areas normally do not overlap with operational areas except for the area directly in front of the glide path beam. The sensitive area is normally larger in both width and length directly in front of the antenna installation, also overlapping the runway and adjacent taxiways. European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 4 2.6.2 However, glide path critical and sensitive areas may become an operational issue if departing aircraft need to enter the runway from the same side as the glide path antenna installation and while landing operations take place (mixed use). In most cases, runway line up is done from the other side, meaning that no specific glide path sensitive area protection measures are necessary. 2.6.3 If it is necessary to line up aircraft from the same side of the runway where the glide path is installed, it will be required to hold aircraft at a suitable location which doesn’t infringe critical or sensitive areas. This will increase the time for departing aircraft to line up on the mixed use runway. For most airports, the CAT I runway-holding position to protect the critical area will be on the taxiway perpendicular to the runway. The CAT II/III runway-holding position to protect the sensitive area will be close to the glide path installation on the parallel taxiway. A CAT I glide path sensitive area is normally not necessary, as already covered by the critical area. If departure runway length is sufficient and a suitable runway-entry taxiway is available, it may also be possible for aircraft to depart without infringing any glide path critical and sensitive areas. 2.6.4 The nominal offset between the glide path antenna and the runway centreline is 120 m. This has been found to provide an optimal compromise between a number of technical and operational factors. In the case the glide path antenna is situated at an offset of 150 m, the overlap of the glide path critical and sensitive areas on such a line-up taxiway will increase. 2.7 Vertical dimensions of the glide path critical and sensitive areas 2.7.1 The vertical dimension of the glide path critical and sensitive areas has not been quantified in ICAO Annex 10, Vol I. However, a direct overflight of the glide path antenna by a large aircraft causing unacceptable multipath is unlikely. During a go-around from a CAT I 200 ft decision height, a 5 degree deviation from centreline is enough for the aircraft to directly overfly the glide path antenna. While this is allowed and protected by the corresponding PANS-OPS criteria, pilots generally maintain good runway alignment when initiating a go-around except if instructed differently. Furthermore, the trailing aircraft whose glide path guidance may be impacted briefly will at most be in the initial stages of the final approach, normally still having sufficient terrain clearance. 2.7.2 It is advisable to ensure that helicopters or drones do not overfly the glide path antenna mast at low height, and to monitor for any pilot reports which could be linked to glide path anomalies caused by aircraft conducting a go-around. 2.8 Air Traffic Controller awareness 2.8.1 In order to make informed decisions, controllers need to know the size and location of the ILS critical and sensitive areas. This information should be part of the air traffic controller training program and should be included in the operations manual. 2.8.2 Controller awareness is also supported by depicting the ILS critical and sensitive areas on aerodrome maps through A-SMGCS. In at least one State, the information is published in the AIP. However, with critical and sensitive areas varying by category of operation and type of aircraft (as described in para 3.3) it may be more difficult to do so. 2.8.3 On more advanced controller working positions, size and location of these variable ILS critical and sensitive areas may be shown on aerodrome surface movement displays that make it much easier to assess whether the ILS critical and sensitive areas are free from violations. An example is provided in Appendix B. European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 5 CHAPTER 3 - PRACTICES FOR OPTIMIZING RUNWAY CAPACITY 3.1 Specific operational practices 3.1.1 This chapter is describing operational practices which may be put in place in order to protect the ILS guidance signals while optimizing the runway capacity when ILS is in use and in particular when LVP are in force. These procedures deviate from ICAO Annex 10, Vol I, and therefore require a State notification to ICAO for SARPS deviation and a specific safety assessment which must be approved by the competent State authority. 3.2 Effects of infringements of critical and sensitive areas 3.2.1 Effects on Aircraft Systems 3.2.1.1 It has been shown that critical and sensitive area violations have an effect on the aircraft systems. The magnitude and impact of these effects is dependent upon many factors including aircraft type, position, speed, geometry, equipment, size and speed of the violating object. Aircraft systems may absorb short time ILS signal fluctuations through the effects of filtering by on-board equipment and the dynamics of the airframe. Note: An example is provided in Appendix C 3.2.1.2 Anomaly detection algorithms have been implemented in some autopilots to detect and mitigate perturbations in the ILS signal. For example, if an aircraft takes off and flies over the localizer, it will cause a disturbance in the beam for aircraft on approach. If those aircraft have anomaly detection algorithms they could be unaffected. The anomaly detection works well for disturbances with a relatively quick onset. However, slow or bias type errors are not easily detected. Therefore, the anomaly detection may not be effective against every possible disturbance of the signal caused by aircraft or vehicles moving in the ILS critical or sensitive areas. 3.2.1.3 Slow or bias type errors that are not detected by the anomaly detection algorithms result in indications to the pilot either through flags, aircraft control actions (from autopilot) or fluctuations of the cockpit display indicators. The length and magnitude of fluctuations are linked to the speed and time of the critical and / or sensitive area violation. 3.2.1.4 These effects need to be analysed in order to determine what is acceptable from an operational point of view. 3.2.2 Effects on Pilots 3.2.2.1 In good visibility, the pilot might fly the aircraft manually, possibly with the help of a flight director. In that case the pilot normally does not “chase the needle“ and keeps the aircraft attitude steady if he observes unsteady localizer (LOC) deviations. In automatic flight, the autopilot might disconnect if the aircraft's attitude becomes unstable due to the autopilot tracking the localizer and then the pilot takes over manually. If visual contact with the runway is established, the localizer might even be ignored. 3.2.2.2 For aircraft without advanced avionics (automatic flight control systems with anomaly detection, flight directors, etc., i.e. normally only for aircraft capable of only CAT I approaches), the pilot can maintain a stable localizer approach course using the gyrocompass heading, taking into account any crab angle to compensate for cross-wind. This means that this will be more challenging in difficult wind conditions. For glide path disturbances while in the early stages of the approach, a pilot European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 6 can try to maintain his vertical descent rate using the vertical speed indicator, provided that the aircraft is not in a deceleration phase due to flaps extensions or such. Continuous checking of approach barometric altitude can also help, especially if a DME to indicate distance to threshold is available. However, in general it is more difficult and more safety-critical for a pilot to manually compensate for glide path disturbances than localizer disturbances 3.2.2.3 In CAT I conditions, the aircraft might be controlled manually or automatically by the autopilot. In manual flight, temporary and unsteady deviations can be absorbed better. The pilot will have a maximum allowable localizer deviation from the centreline (normally 1 dot on the LOC display). When this is exceeded, the approach should be discontinued. 3.2.2.4 In CAT II/III conditions the aircraft will usually be flown automatically. The pilot will initiate a missed approach when certain maximum deviations of the flight parameters are exceeded. These are usually more stringent than the ones in CAT I conditions, for example LOC deviation of 1/4 of a dot, bank angle of more than 7 degree (which could be caused by the autopilot tracking a LOC deviation), etc. 3.2.2.5 In addition, modern aircraft will display a ground track symbol on the PFD compass scale. If the aircraft is tracking the correct and undisturbed localizer beam this track symbol should be on the runway magnetic heading. Especially during LVP, deviation of this track symbol from the runway magnetic heading will be a trigger for initiating a go-around. 3.2.2.6 The pilot will especially pay attention to these maximum deviation parameters if the aircraft is below a certain altitude, for example 1000 ft and/or MSA (depending on operator's standard operating procedures). Any deviation of the parameters beyond the limits will necessitate a go-around. 3.3 Establishing the localizer critical and sensitive areas 3.3.1 Localizer critical and sensitive areas should be established by the responsible service provider using guidance provided in ICAO Annex 10, Vol I, recommendations from the respective ILS manufacturer and through site specific studies. 3.3.2 For airports with low traffic density, a worst case critical and sensitive area may be defined based on the largest aircraft in operation at that airport to cover all operations (“one-size-fits-all”). Even in this case, it may be advisable to establish separate areas for CAT I and CAT II/III operations so as to prevent overly restrictive practices. 3.3.3 For those airports where traffic mix and density dictates, it is considered essential to define critical and sensitive areas for different categories of operation and aircraft. 3.3.4 The critical and sensitive areas need to be revised based on airport development plans and changing traffic mix. 3.4 Protection of localizer critical and sensitive areas 3.4.1 In accordance with the ICAO Annex 10, Vol I, critical area definitions, infringements of the localizer critical area will cause out-of-tolerance disturbances to the ILS signal within the entire localizer coverage volume or in other words a situation where the integrity of the ILS signal is no longer maintained. The operational impact of these out-of-tolerance disturbances depends on various factors like category of operation, distance to threshold and also aircraft specific factors. 3.4.2 Under specific circumstances, it may be permissible to accept infringements of the critical area provided that operational procedures derived from a thorough safety assessment are in place to mitigate the adverse effects. However, the general rule should be and remain that the critical area has European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 7 to be free from aircraft or vehicles during all ILS operations. In accordance with ICAO Doc 9859 (Safety Management Manual, 4th Edition, 2018) para § 9.5.4 Safety performance monitoring and measurement, it is recommended to monitor occurrences that can be attributed to particular CSA infringements in order to determine if these infringements can be tolerated or a procedural and/or infrastructural modification is required. 3.4.3 According to the sensitive area definition, infringements of the sensitive area will not cause unacceptable ILS signal distortions at a distance beyond 2 NM to threshold. Therefore, the sensitive area needs to be protected only when the next arriving aircraft is within a distance of 2 NM to threshold. 3.4.4 Some Air Navigation Service Providers are using 1 NM instead of 2 NM as a limit for landing clearance delivery and are computing the sensitive areas to protect operations below the 1 NM corresponding heights. 3.4.5 Due to the fact that the arriving aircraft is very close to the threshold in a critical landing phase, there is no room for exceptions from this rule in CAT II/III operations. 3.4.6 To address the vertical dimension of the critical and sensitive areas for mixed mode operation runways, the ICAO Doc 9365 (Manual of All Weather Operations, 4th Edition, 2017) requires that in LVP the aircraft taking off has passed over the ILS localizer antenna before the arriving aircraft reaches a point 2 NM (typically) from touchdown. To achieve this, it is recommended that the departing aircraft commences its take-off run before the arriving aircraft reaches a point 6 NM from touchdown. A larger distance of the localizer from the stop end of the runway may require a larger separation between departing and arriving aircraft. This represents one of the disadvantages of locating the localizer at these larger distances from the opposite threshold. Although ICAO Doc 9365 (Manual of All Weather Operations, 4th Edition, 2017) does not consider nearby runways, similar procedures may be applied for take-off on such runway if critical or sensitive volumes of the operating localizer are being infringed by departing aircraft. 3.4.7 CAT I Operations 3.4.7.1 ICAO Annex 10, Vol I, requirements for ILS CAT I signal-in-space are less stringent than for CAT II/III. This therefore translates into much smaller dimensions of the localizer critical and sensitive areas for ILS CAT I compared to those required for CAT II/III operations. 3.4.7.2 With respect to the integrity and continuity of service requirements for CAT I ground systems, ICAO Annex 10, Vol I, contains only recommendations (ref. chapter 3.1.3.12). However, it should be noted that these recommended practices are specifications “the uniform application of which is recognized as desirable in the interest of safety, regularity or efficiency of international air navigation, and to which Contracting States will endeavour to conform in accordance with the Convention.” (Foreword to ICAO Annex 10, Vol I, 7th edition, July 2018). In one State, the CAT I sensitive area is safeguarded only when the visibility is below 1.5 km and/or the ceiling is at or below 300 ft. 3.4.7.3 Short-duration infringements of the localizer critical and sensitive areas by arriving aircraft 3.4.7.3.1 If the CAT I critical area (e.g. the area for A380 operation) overlaps parts of the runway and runway exits and the concerned aircraft is required to use one of these exits within the critical area, then the ILS localizer signal will be disturbed beyond allowed tolerances. 3.4.7.3.2 If the CAT I sensitive area (e.g. the area for A380 operation) overlaps parts of the runway and runway exits and the concerned aircraft is required to use one of these exits within the sensitive area, then the ILS localizer signal will be disturbed beyond allowed tolerances for the next arriving aircraft within 2 NM until decision height. European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 8 3.4.7.3.3 These short-duration infringements are between 5 and 20 s and correspond to an aircraft taxiing without stopping to vacate the runway after landing through a critical area extending on the runway surface (Appendix C). 3.4.7.3.4 Such short-duration infringements of the localizer critical and sensitive areas could be allowed when the pilots on final approach have visual contact with the runway and are being warned that ILS distortions are to be expected. 3.4.7.3.5 All operational procedures which would allow infringements of the localizer critical and sensitive areas in CAT I operations when the pilots have no visual contact with the runway should be based on a safety assessment and should be approved by the competent authority 3.4.7.4 Very Short-duration infringements of the localizer critical area by departing aircraft 3.4.7.4.1 Departing aircraft may cause very short-duration ILS signal distortions when overflying the localizer antennas. These very short-duration infringements are below 5 s and therefore considered as acceptable in CAT I operations. This is applicable irrespective of arriving aircraft position. 3.4.8 CAT II/III operations 3.4.8.1 In normal CAT II/III operations, the localizer critical areas should be free of any aircraft or vehicles at all times. In the event that an aircraft vacating or crossing the runway infringes the localizer critical area, the ILS must be considered unusable for the period of the infringement. 3.4.8.2 Procedures to be followed in the respect of the localizer sensitive area can be found in ICAO Doc 9365 (Manual of All Weather Operations, 4th Edition, 2017) and are not repeated here. 3.4.8.3 Short-duration infringements of the localizer critical area by arriving aircraft 3.4.8.3.1 Some service providers have implemented special operational procedures to allow short- duration infringements of the localizer critical area in CAT II/III operations. These short-duration infringements are between 5 and 20 s and correspond to an aircraft taxiing without stopping to vacate the runway after landing through a critical area extending on the runway surface (Appendix C). 3.4.8.3.2 In circumstances where these special operating procedures are in force and if the affected aircraft has not reached 4 NM (or more, as determined by the local safety assessment) from threshold, short-duration infringements are tolerated and flight crews are warned of potential distortions of the localizer signals due to aircraft movement within the localizer critical areas, otherwise a missed approach is initiated by ATC. 3.4.8.3.3 A safety assessment should be approved by the competent authority for all operational procedures that may allow short-duration infringements of the localizer critical area during CAT II/III operations. 3.4.8.4 Very Short-duration infringements of the localizer critical area by departing aircraft 3.4.8.4.1 Some service providers have implemented special operational procedures to allow very short-duration infringements of the localizer critical area in CATII/III operations by departing aircraft. These very short-duration infringements are below 5 s and correspond to an airborne aircraft flying through the critical volume of the localizer while departing from the landing or a nearby runway. 3.4.8.4.2 In circumstances where these special operating procedures are in force and if the affected aircraft has not reached 2 NM (or more, as determined by the local safety assessment) from threshold, very short-time infringements are tolerated and flight crews are warned of potential distortions of the European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 9 localizer signals due to departing aircraft flying through the localizer critical volume, otherwise a missed approach is initiated by ATC. 3.4.8.4.3 A safety assessment should be approved by the competent authority for all operational procedures that may allow very short-time infringements of the localizer critical area during CAT II/III operations. 3.5 Dynamic management of localizer critical and sensitive areas as used for different categories of aircraft and operation 3.5.1 At aerodromes where a mix of traffic exists, such that the use of multiple critical and sensitive areas have a capacity benefit then dynamic management of these areas from ATC may be implemented. 3.5.2 In this case, different sized critical and sensitive areas are used for the protection of the following arrival (and for guided take-off – departure) by protecting the appropriate sized critical and sensitive areas according to the size of the aircraft causing the disturbances. 3.5.3 In order to manage the different critical and sensitive areas, for the varying traffic mix, ATC must have aircraft positional information in relation to the applicable critical and sensitive areas. This can be displayed through A-SMGCS or other means as appropriate. 3.5.4 For example a single operational runway where medium (737, A320), heavy (777, A340, 747) and very large aircraft (A380) are operating, up to three separate localizer critical and sensitive areas could be used. In order to maintain adequate protection of the ILS localizer, the appropriate areas must be enforced for the type of aircraft that is using the runway. Note: It is the size of the aircraft on the runway or taxiway and therefore likely to infringe the critical and sensitive area that is taken into consideration NOT the size of the aircraft on final approach 3.5.5 Depending on traffic density and controller workload, it is foreseen that as many or as few critical and sensitive areas may be used in order to provide benefits without jeopardising the requirements of the ILS signal-in-space. Human factor issues need to be considered for operational procedures covering the dynamic management (e.g. unnecessary or excessive complexity should be avoided). 3.5.6 For these cases where dynamic management of critical and sensitive areas is not practical, it is recommended that the critical and sensitive areas for the largest aircraft are used; however this may adversely affect aerodrome capacity when the largest aircraft is not present. 3.6 Management of glide path critical and sensitive areas 3.6.1 Aircraft within the critical and sensitive areas in front of the glide path antenna will cause distortions for the aircraft in approach and may cause the glide slope angle to decrease. The magnitude of the distortions (and decrease of the angle) is depending on the size, orientation and distance to the glide path of the aircraft penetrating the glide path critical and sensitive areas. The effect of distortions on a landing aircraft is highest during CAT III and/or when the distance to the threshold (THR) is closer than the FAP. For safety reasons, infringements of the glide path critical and sensitive areas should not be considered at all when the glide path is used. 3.6.2 Special care has to be taken when considering the taxiways layout in the vicinity of the glide path antenna. Overlap between glide path (GP) critical and sensitive areas and taxiways has to be avoided, as otherwise the runway capacity will be impacted. European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 10 European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 11 APPENDIX A – Marking of critical and sensitive areas European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 12 European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 13 APPENDIX B – Display of critical and sensitive areas European guidance material on management of ILS critical and sensitive areas First Edition: June 2020  Page 14 APPENDIX C – Examples of LOC deviations and aircraft reaction Background information on these examples can be found in AWOG27 IP03, which has been published in further support of EUR Doc 040. 1. Measured LOC deviations The following picture shows measured LOC deviations with an A380 and a 747 respectively when leaving runway 25L via taxiway “R” at Frankfurt airport. The distance between aircraft and LOC 25L is 260 m. The two scenarios on the following pages depict the LOC deviations as seen on aircraft (747 and 737) and the aircraft reactions (offset from centerline and roll angle). For each scenario, the displayed Flight Technical Error (in dot, 2 dots being full scale deviation on the Course Deviation Indicator), status of and impact on autopilot and flyability assessment by the pilot are indicated. European Guidance Material on All Weather Operations at Aerodromes  Page 15 2. Scenario 1: A380 leaving runway at a distance of 260m to LOC Scenario 1a: Impact on approaching 747 at 5.5 to 4 NM (A380-747) CDI: ~ 1 dot Autopilot: no reaction Flyability assessment by the pilot: tolerable, would contact ATC European Guidance Material on All Weather Operations at Aerodromes  Page 16 Scenario 1b: Impact on approaching 737 at 5.5 to 4 NM (A380-737) CDI: 1 to 1.9 dot Autopilot: disengaged at 3.6 NM to threshold Flyability assessment by the pilot: would initiate go-around during all categories of operation European Guidance Material on All Weather Operations at Aerodromes  Page 17 Scenario 2: 747 leaving runway at a distance of 260m to LOC Scenario 2a: Impact on approaching 747 at 5.5 to 4 NM (747-747) CDI: 0.5 dot Autopilot: remained engaged, 5° bank angle Flyability assessment by the pilot: not “nice” but acceptable, would contact ATC during LVP European Guidance Material on All Weather Operations at Aerodromes  Page 18 Scenario 2b: Impact on approaching 737 at 5.5 to 4 NM (747-737) CDI: 0.8 dot Autopilot: remained engaged, 8° bank angle Flyability assessment by the pilot: tolerable, ATC information required - END - European Guidance Material on All Weather Operations at Aerodromes Saatja: Moonika Käst <[email protected]> Saadetud: 02.12.2020 10:30 Adressaat: Silver Luik <[email protected]>; <[email protected]>; <[email protected]> Koopia: Roman Kulikov <[email protected]>; 'Aleksandr Borovkov' <[email protected]>; 'Silja Mesila' <[email protected]> Teema: EUROPEAN GUIDANCE MATERIAL ON MANAGEMENT OF ILS CRITICAL AND SENSITIVE AREAS Manused: EUR Doc 040_2020_ILS kriitiline ja tundlik ala.pdf Tere! 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