EUROCONTROL COOPERATIVE NETWORK DESIGN

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1 i EUROCONTROL COOPERATIVE NETWORK DESIGN Implementation of the 8.33 khz Voice Channel Spacing Safety Impact Assessment Report Ref: :8.33<195-SAFREP IR Edition :1.0 Edition Date :02/01/2011 Status :Proposed Issue Class :CND Stakeholders

2 DOCUMENT CHARACTERISTICS Implementation of the 8.33 khz below FL 195 Safety assessment report Document Identifier Edition Number: 1.0 Abstract Edition Date: 2 Feb 2011 This safety impact assessment is addressing the implementation of 8.33 khz below FL195 in the ICAO EUR Region where EU Member States are responsible for the provision of air traffic services. This safety assessment is addressing the safety impact of such implementation on the air traffic services which are supported by the air-ground VHF voice communication. Furthermore it addresses also the potential safety impact on the control of the movement of ground vehicles on the manoeuvring areas. Considering this scope, this safety assessment does address the impact on: Air Traffic services delivered to pilots in controlled/uncontrolled airspace and for aerodrome operation where two way radio communication is required The control of the movement of ground vehicle in controlled aerodromes where two way radio communication is required The implementation of 8.33 khz below FL195 in the ICAO EUR Region where EU Member States are responsible for the provision of air traffic services is characterised by: the Interim Implementation for 2014 to ensure a given number of conversions take place in the EU States area defined in the implementing rule 1, the final Implementation for 2018 to ensure 8.33 khz spacing of all possible voice channels in the EU Member States airspace. The safety target was set to demonstrate that ST#1 the risk of an accident following the complete conversion to 8.33 khz VCS shall not be significantly greater than before the start of the introduction of 8.33 khz VCS ST#2 the risk of an accident during the transition to the complete conversion to 8.33 khz VCS shall be reduced as far as reasonably practicable. The overall conclusion is that deployment of 8.33 khz VCS in the airspace of IR applicability below FL 195 according to the draft VCS II IR [16] has the potential to satisfy the above Safety Targets, but some additional safety requirements must be added to the rule. Indeed, it has been shown that all Safety Requirements identified during this safety impact assessment have been satisfactorily addressed either by the draft VCS II IR [16] or by the future draft VCS II IR, which will include the additional/modified requirements, or by other existing regulations (e.g. ICAO). Keywords Implementing Rule, Safety activities, Safety Assurance, Safety Argument, Hazards Contact Person(s) Tel Unit Daniela Grippa daniela.grippa@eurocontrol.int Bruno Rabiller bruno.rabiller@eurocontrol.int CND COE/ PM/ SY CND COE/ PM/ SY 1 This area is called in the rest of the document area of applicability defined in IR, Annex I

3 STATUS, AUDIENCE AND ACCESSIBILITY Status Intended for Accessible via Working Draft General Public Intranet Draft CND Stakeholders Extranet Proposed Issue Restricted Audience Internet ( Released Issue Path: ELECTRONIC SOURCE Host System Software Size Windows_NT Microsoft Word Kb

4 DOCUMENT CHANGE RECORD The following table records the complete history of the successive editions of the present document. EDITION NUMBER EDITION DATE REASON FOR CHANGE PAGES AFFECTED Rev IR 15/12/2010 Creation All Feb 2011 Internal Review All WRITTEN BY CHECKED BY APPROVED BY D. Grippa/ B. Rabiller D. Grippa/ B. Rabiller D. Booker, P. Thorsen J. Roca

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6 Contents 1. INTRODUCTION Implementation of 8.33 khz VCS Overview Scope and process of the Safety Impact assessment General Approach to Safety Assessment of 8.33 VCS Safety Targets Description of the operational environment Air Traffic Services and the A/G Voice Communication Infrastructure The Operational Environment for the Interim Phase The Operational Environment for the Final Phase Safety Assessment Results for aircraft operation Safety Scenarios Assessed Success Approach Failure Approach Risk Assessment Overview Safety Scenario # Safety Scenario # Safety Scenario # Risk Quantification Impact on ground vehicle operation Introduction Safety Targets Safety Scenarios Assessed Success Approach Failure Approach Risk Assessment Overview Safety Scenario # Safety Scenario # Risk Quantification Caveats Assumptions Safety Issues Conclusions and Recommendations Conclusions Recommendations How the draft IR is addressing the outcome of the safety impact assessment 38 Annex 1: Glossary and References A1-1 Glossary of Terms and Abbreviations A1-2 References Annex 2: Air Traffic Services supported by the A/G Voice Communication service

7 A2.1 Air Traffic Control Service A2.2 Flight Information Service (FIS) A2.3 Air Traffic Advisory Service Annex 3: Safety Log A3.1 Safety Requirements A3.2 Assumptions A3.3 Issues Annex 4: Identified Safety Requirements versus the content of the Draft VCS II IR 46 7

8 8 1. INTRODUCTION 1.1. Implementation of 8.33 khz VCS Overview On 15 March 2007, the mandatory carriage and operation of 8.33 khz VCS capable radio equipment came into effect above FL 195 in the ICAO EUR Region. In October 2007, the European Commission published the Regulation ER 1265/2007 which, in particular, includes important articles concerning ground radio conversions and the requirements for State aircraft. In spite of the recent decreasing air traffic levels, the demand for new VHF assignments continues and is expected to increase once traffic levels rise again. Therefore, Europe is reviewing the need for 8.33 khz VCS, as well as other measures to alleviate VHF congestion. The Eurocontrol Stakeholder Consultation Group (SCG) 10 th meeting - held 25/26 Feb 2009 agreed the following conclusions relating to 8.33 khz VCS : Supported a phased implementation of 8.33 khz VCS in the ICAO EUR Region; Agreed that EUROCONTROL should: o o o Develop a European Implementation Plan with the participation of all affected stakeholders, also taking into account the issue of funding; Provide advanced notice to affected stakeholders on potential pan-european milestones and timescales; Ensure a coherent approach between the programme work and the European Commission (EC) Regulation 1265/2007 Noted the related MILHAG support and consideration regarding the phased implementation in terms of time, airspace and geographical areas The SCG was advised on the intention to modify the EC regulation 1265/2007 (the AG-VCS Implementing Rule) in order to address 8.33 khz VCS forward-fit, frequency-usage transparency and the phased deployment. The 8.33 khz VCS stakeholders have analysed the options for the phased implementation below FL 195 and a Europe-wide formal consultation took place early in 2010 to agree the way forward. Two implementation scenarios were proposed to the 8.33 khz stake holders: Scenario 1 Development of regulatory provisions identifying three implementation milestones. Forward Fit Phase starting from 2012 to ensure all new radios comply, Interim Phase by the 31 st December 2014 to ensure a given number of conversions take place, in the European states. Final Phase by the 31 st December 2018 to ensure the conversion to 8.33 khz spacing of all possible European voice channels Scenario 2 Development of regulatory provisions identifying two implementation milestones. Forward Fit Phase starting from 2012 to ensure all new radios comply, Final Phase by the 31 st December 2018 to ensure the conversion to 8.33 khz spacing of all possible European voice channels. Both scenarios propose a Forward Fit Phase and a Final Phase ; these are identical in each case. As result of the consultation of the 8.33 khz stakeholders the definition of two areas where the implementation will be realised, following two different scenarios has been proposed:

9 Part of the ICAO EUR region 2, where the Interim and Final Phases would be required and the rest of the ICAO EUR Region 3, where only the Final Phase would be required Scope and process of the Safety Impact assessment This safety impact assessment is addressing the implementation of 8.33 khz below FL195 in the ICAO EUR Region where EU Member States are responsible for the provision of air traffic services. This safety assessment is addressing the safety impact of such implementation on the air traffic services which are supported by the air-ground VHF voice communication. Furthermore it addresses also the potential safety impact on the control of the movement of ground vehicles on the manoeuvring areas. Considering this scope, this safety assessment addresses the impact on: Air Traffic services delivered to pilots in controlled/uncontrolled airspace and for aerodrome operation where two way radio communication is required The control of the movement of ground vehicle in controlled aerodrome where two way radio communication is required. This safety assessment does not address the safety impact on: The performance of airline communications 4 which are supported by the air-ground VHF voice communication even if OPC (OPerational Control) frequencies have to be converted in 8.33 khz. Apron management services because air traffic control has normally no responsibility for control of vehicles on apron areas (ICAO Doc 9137 Part 8) and VHF voice communication might not be used (e.g. use of digital radio communication system) Safety assessment typically start at the ATM service level this level may be thought of as being in the interface between the service provider and the service user. Such an approach is particularly valid for the introduction of 8.33 khz voice-channel spacing (VCS) since VHF voice is currently the main mean of communication across the provider / user interface for ATM services to GAT and is likely to remain so for the next two decades. Safety Objectives are specified at the service level, for three purposes: to capture what has to happen in order for the services to operate as required to mitigate the consequences of failure / degradation of the ATM services, however caused to limit the frequency with which the causes of such failures may occur so as to achieve an acceptable level for the associated risk, taking account of the above mitigations. In the first two cases, the Safety Objectives address the functionality and performance to be achieved. In the 3 rd case, the Safety Objectives address the integrity to be achieved 5. In all three cases, only what has to be achieved is specified at the service level this helps to ensure the completeness, correctness and consistency of the Safety Objectives without the unnecessary (at this level) detail of how, or by whom, the Safety Objectives will be achieved. 2 Member States for this interim phase are: Austria, France, Germany, Hungary, Ireland, Italy, Luxembourg, The Netherlands, and United Kingdom see Annex 1 of the IR. 3 Applicable to EU members States responsible for the provision of ATS 4 Airline Operational Communication (AOC) and/or Airline Administrative Communication (AAC) 5 The traditional definition of a Safety Objective (including that in EC 2096/2005) is limited to the 3 rd case. However, recent experience on many EUROCONTROL projects has shown to be very useful to extend this definition to include the first two cases. 9

10 Safety Requirements, on the other hand, are the means by which the Safety Objectives are achieved for this reason they are specified at the system level and result from the appropriate allocation of the Safety Objectives on to the elements of the functional system in general, covering equipment, procedures and human resources. This safety assessment has considered the different safety materials developed prior to the initial safety Impact assessment ([1], [2] and [3] ) and the safety materials developed during the initial safety impact assessment ([4], [5], [6], [7], [8] and [9]). 2. GENERAL APPROACH TO SAFETY ASSESSMENT OF 8.33 VCS BELOW FL 195 Hypothetically, it could be said that if a homogeneous channel spacing (i.e. either 8.33 khz or 25 khz) were to exist in the airspace, and there were to be a corresponding homogeneous aircraft fit, then any hazards associated with air-ground and ground-ground RT communications would be the same whichever channel spacing was deployed - i.e. loss of communication - due to voice-communications equipment failure or incorrect frequency selection by an aircraft or ground vehicle distortion of communication - due to interference caused by incorrect frequency selection by an aircraft or ground vehicle, by inappropriate frequency assignments to proximate sectors, or by external 6 events such as natural phenomena or man-made interference. For the purposes of this safety impact assessment, it is assumed that the likelihood and consequences of any of the following are not affected by the change from 25 khz VCS to 8.33 khz VCS: voice-communications equipment failure external interference events Controller transmitting a wrong frequency to the pilot. Therefore, any risk associated with these three hazard causes does not change and can, therefore, be excluded from this safety assessment, which is concerned specifically with the effects of the introduction of 8.33 khz VCS. Furthermore, it has already been established, from the previous deployment of 8.33 khz VCS above FL 195, that: an 8.33 khz VCS-equipped aircraft is fully able to communicate with a ground station that is equipped with either 25 khz or 8.33 khz VCS a 25 khz VCS-equipped aircraft can communicate only with a 25 khz VCS ground station The VHF air-ground communication frequency assignment planning criteria (ICAO EUR Doc 011) are properly addressing the 8.33 khz spaced channels and no specific assignment criteria are relative to the altitude (implementation above or ). Thus a hazardous situation related to the introduction of 8.33 khz VCS would exist if: an 8.33 khz VCS-equipped aircraft were to mistune a (correct) 8.33 khz VCS frequency a 25 khz VCS-equipped, non-exempt aircraft were to enter, or attempt to enter, a sector that uses primarily 8.33 khz VCS - for example, by selecting an old 25 khz VCS frequency or by trying to select the 8.33 khz VCS frequency assigned to the sector. 6 External here means from outside of the aviation VHF RT communications system 10

11 a 25 khz VCS-equipped, exempt aircraft were to enter, or attempt to enter, a sector that uses primarily 8.33 khz VCS, unless facilities / procedures for handling such aircraft had already been put in place. Therefore, the safety assessment has to address the above from three perspectives: the specification of Safety Objectives, and then Safety Requirements, to avoid hazardous situations occurring, wherever possible the specification of Safety Objectives, and then Safety Requirements, such that if hazardous situations do occur, for whatever reason, then their effects in terms of safety are reduced as much as possible an estimation of the likely risk associated with the occurrence of hazardous situations, taking account of the above mitigations. The first perspective is known as the success approach; the other two together are known as the failure approach. 3. SAFETY TARGETS Two Safety Targets for which the Safety Objectives are to be derived: ST1 the risk of an accident following the completion of the Final Phase of conversion to 8.33 khz VCS shall not be significantly greater than before the start of the Interim Phase ST2 the risk of an accident during the period between the start of the Interim Phase and completion of the Final Phase, of conversion to 8.33 khz VCS shall be reduced as far as reasonably practicable. 4. DESCRIPTION OF THE OPERATIONAL ENVIRONMENT 4.1 Air Traffic Services and the A/G Voice Communication Infrastructure The Air-Ground (A/G) Voice Communications infrastructure supports the Air Traffic Services (ATS) system by providing the necessary Aeronautical mobile service for safe operations. As specified in ICAO Annex 11, the Air Traffic Services supported by the A/G voice comms are the following: Flight Information Service in uncontrolled airspace Air Traffic Advisory Service in uncontrolled airspace Air Traffic Control Service in controlled airspace (area, approach or aerodrome) In addition to the above services, an Alerting Service is automatically provided to all aircraft receiving an Air Traffic Control Service and, as far as is practicable, to all other aircraft whose pilots have filed a flight plan or are otherwise known to air traffic services. The communication requirements associated with the delivery of each of these services, to General Air Traffic (GAT), are currently provided through a VHF air/ground infrastructure supporting both voice and data communications. Air traffic control will continue to depend heavily upon A/G voice communications. When data-link communication becomes more widespread, voice will still be used for tactical clearances and nonstandard instructions (in line with the SESAR Concept of Operations). Future Communication Infrastructure (FCI) is not expected to replace the VHF AM (25 and 8.33 khz VCS) technology before

12 A/G voice comms currently uses VHF (very high frequency), AM (amplitude modulation) with channels spaced at 25 khz or 8.33 khz 7. For radio communication the aeronautical VHF band of 118 MHz to 137 MHz is used. In order to provide a high quality of service to many aircraft at the same time, the airspace is organized in sectors - i.e. individual blocks of three-dimensional space which are defined by a bottom and top altitude limit and geographical points (sector boundaries) - with each sector allocated specific voice communication frequencies. Continuous two-way radio-communication is required for IFR operations in all airspace classes (A to G) whereas for VFR operation it is required for class A to D, but not for class E to G. Currently, the A/G voice comms infrastructure uses only one channel spacing standard (25 khz VCS). Annex 2 of this report describes the services supported by the A/G voice comms and should allow a better understanding of the safety role of the A/G voice comms service in the operational environment during the assessment. 4.2 The Operational Environment for the Interim Phase The implementation of 8.33 khz VCS will start with an initial phase called the Interim Phase as described in Figure 1 below. The Interim Phase is described in more detailed in [13]. As agreed after the stakeholder consultation, the Interim Phase is applicable to a number of States in the ICAO EUR region which are listed in the Annex I of the draft IR [16] khz airspace above FL 195 FL khz 8.33 khz 25 khz 8.33 khz Airspace class D,E,F or G Airspace class A,B or C E.g. Airspace class not converted because ANSP already converted more than 25 % of their ACC frequencies Airspace class A,B or C (or possibly other airspace class e.g. D,F,G or E can be converted as permitted by the IR) Minor TMA 25 khz E.g. Airspace class E Airport 1 25 khz E.g. FL khz or no radio required Airport 3 25 khz Airspace class E,F or G Major TMA 8.33 khz E.g. Airspace class A Airport 2 25 khz Figure 1: Overview of the 8.33 khz Interim Phase 7 As noted in section 1.1 above, the mandatory carriage and operation of 8.33 khz VCS capable radio equipment came into effect in the ICAO EUR Region above FL 195 (but not ) on 15 March

13 ATS airspace is classified and designated in ICAO Annex 11, Section 2.6 Classification of Airspaces using the seven airspace classes (A to G). Annex 11, Appendix 4 identifies for each airspace class (A to G) and type of flight (IFR or VFR), where voice radio communication is required. All the airspace of classes A, B, C, D and E is defined as Controlled airspace while the airspace of classes F and G are defined as Uncontrolled airspace. During the Interim Phase of conversion to 8.33 khz VCS, the more likely scenario is that part of the airspace Class A, B and C will be converted to 8.33 khz channel spacing while the airspace D, E, F and G will continue to operate the 25 khz channel spacing frequencies. This means that in the participating States all non-exempt aircraft operating in class A, B or C airspace under IFR shall be equipped with radio equipment with the 8.33 khz voice channel spacing (VCS) capability. State aircraft are exempt from this requirement and in some States they may continue to use 25 khz VCS. When the Interim Phase is completed, in December 2014, it is assumed that ANSPs will have performed a number of conversions equivalent to at least 25% of their 25 khz ACC assignments for which conversion is feasible. This means that airspace classes A, B, C will not be completely converted during the Interim Phase, and that conversions could also take place in other airspace classes (D to G) and/or for Approach/Tower services. The conversion to 8.33 khz VCS during this Phase is considered not to be feasible in the following cases: sectors where 25 khz offset carrier system is utilised, assignments that must stay in 25 khz VCS as a result of a local safety requirement, 25 khz VCS assignments that are used to accommodate State Aircraft, MHz channel (emergency frequency) and the VHF Data Link frequencies will stay in 25 khz VCS. This Phase is therefore characterised by airspace which,, is converted (green in Figure 1 ) or not converted (blue in Figure 1) to 8.33 khz VCS. Airspace users must be equipped with radio equipment with the 8.33 khz VCS capability when flying in 8.33 khz VCS airspace. Because the 8.33 khz Climax 8 will not be applied (only applied in 25 khz), the latest EUROCAE specification will not be mandatory (EUROCAE ED 23C). The Specification of 8.33 khz VCS will not support the use of 8.33 khz offset carrier frequency (Climax) either for the Interim Phase or the Final Phase From the airspace users perspective, it is foreseen that: 8.33 khz VCS airspace will have the same accommodation of non-8.33 khz VCS State aircraft as is the case above FL 195, Airspace users will be affected only if flying in 8.33 khz VCS airspace, Airspace users equipped with or without 8.33 khz VCS equipment will co-exist in the airspace. It is important to note that the Interim Phase objective is to reach a target number of conversions without prescribing a specific airspace to convert. This is likely to lead to non-homogeneous 8.33 khz conversion of sectors/tmas from one State to the other and even potentially within a State. Therefore, as a consequence of non-homogeneous conversion, airspace users may not be able to easily determine the VCS equipment requirements for each part of the airspace using a simple rule. Rather, the airspace users will have to refer to the relevant Aeronautical Information Publication (AIP) to identify the VCS equipment requirements for the airspace they are planning to use. 8 Climax=offset carrier frequency function. 13

14 4.3 The Operational Environment for the Final Phase This Safety Impact Assessment addresses also the so-called Final Phase as described in Figure 2 below. The Final Phase is described in more detailed in [13] and, as agreed after the stakeholder consultation, it is applicable to the ICAO EUR Region where EU Member States are responsible for the provision of air traffic services khz airspace above FL 195 FL khz 8.33 khz 25 khz 8.33 khz E.g. Airspace where conversion is not feasible (e.g. climax sector) Minor TMA 8.33 khz 8.33 khz or no radio required Major TMA 8.33 khz Airspace class E,F or G Airport khz Airport khz Figure 2 Overview of the 8.33 khz Final Phase Airport khz The Final Phase is consisting of the full deployment of 8.33 khz VCS. It will lead to all frequency assignments in the aeronautical mobile communications service band being converted to 8.33 khz channel spacing, except for some very specific cases as follows: sectors where 25 khz offset carrier system is utilised, assignments that must stay in 25 khz as a result of a local safety requirement, 25 khz assignments used to accommodate State Aircraft, MHz channel (emergency frequency) and the VHF Data Link frequencies will stay in 25 khz spacing. The Final Phase is therefore characterised by airspace / sectors which,, are largely converted (green in Figure 2) but exceptionally not converted (blue in Figure 2) to 8.33 khz channel spacing. Airspace users must be equipped with radio equipment with the 8.33 khz channel spacing capability when flying in the airspace of IR applicability except if exempted. From the airspace user s perspective, it is foreseen that: 8.33 khz VCS airspace will have the same accommodation of non-8.33 khz State aircraft as is the case above FL 195 (exemption policy) All airspace users will be affected by this Phase except the exempted users 14

15 All airspace users shall be equipped with radio equipment with 8.33 khz VCS except the exempted users. Any mismatch of the flight crew frequency selection and the instructed frequency can lead to an ineffective voice communication service jeopardizing the transmission of ATC clearance or ATS information. As all the airspace users will be impacted by the change, those that were not operating above FL 195 hitherto will be new to the use of the 8.33 khz VCS, potentially increasing the wrong frequency selection by flight crew, in the short term. The following Figure 3 summarise the implementation milestone for the introduction of the 8.33 khz as defined in the draft IR [16] &7 All new radios to be 8.33 khz capable 8 All radio updates to be 8.33 khz capable 9 All IFR aircraft flying in class A-C airspace of the IR applicability area defined in Appendix 1 to be 8.33 khz capable More than 25% of possible freqs in Class A-C to be converted to 8.33 khz for the IR applicability area defined in Appendix 1 16 All aircraft and ground radios to be 8.33 khz capable 15 All OPC freqs to be converted to 8.33 khz All remaining possible freqs to be converted to 8.33 khz Key n Article 3(n) IR reference After (date) Before (date) Important Note: Figure khz Implementation Milestones For States where only the Final Phase is foreseen, a transition period must take place so that the Final Phase will be completed by the 31 st December If some States were start this transition before 1 January 2018 it is likely that the situation would be very similar to the one described for the Interim Phase i.e. there would be a non-homogeneous use of 8.33 khz VCS (i.e. a mix of aircraft capability and a mix of airspace assignments). The main difference between the transition period and the Interim Phase would be that no earliest date is fixed at moment for the start and the end of the transition. 5. SAFETY ASSESSMENT RESULTS FOR AIRCRAFT OPERATION. This safety impact assessment is addressing the impact of the 8.33 khz implementation on air traffic services delivered to aircraft operation in Enroute, Terminal airspace and during landing and taxiing. 15

16 The implementation of 8.33 khz below FL195 in the ICAO EUR Region where EU Member States are responsible for the provision of air traffic services is characterised by: the Interim Implementation for 2014 to ensure a given number of conversions take place in the EU States area defined in the implementing rule 9, the Final Implementation for 2018 to ensure 8.33 khz spacing of all possible voice channels in the EU member States airspace. 5.1 Safety Scenarios Assessed The possible aircraft operations when considering the Interim Phase is depicted in Figure 4 and is applicable to European States listed in the VCSII IR Annex 1. For the Final Phase, which is applicable to all EU member States, Figure 5 is depicting such case. It should be noted that for the Final Phase and outside of the airspace where EU Member States are responsible for the provision of air traffic services, the 25 khz VCS might continue to be used and this aspect has to be considered during the safety assessment khz airspace above FL 195 FL KhZ 8.33 KhZ 25 KhZ 8.33 KhZ Major TMA 8.33 khz Transit Flight Minor TMA 25 khz Transit Flight Major TMA 8.33 khz 25 KhZ or no radio required Airport 1 25 khz Airport 2 25 Khz Figure 4 : A/C operations when considering the Interim Phase 9 This area is called in the rest of the document area of applicability defined in IR Annex I 16

17 8.33 khz airspace above FL 195 FL KhZ 8.33 KhZ Transit Flight 25 KhZ E.g. Airspace where conversion is not feasible (e.g. climax sector) 8.33 KhZ Major TMA 8.33 khz Minor TMA 8.33 KhZ Transit Flight Major TMA 8.33 khz 8.33 KhZ or no radio required Airport 1 Airport KhZ 8.33 KhZ Figure 5: A/C operations when considering the Final Phase The following scenarios for the safety assessment were deduced from the above description: Safety Scenario # khz VCS-equipped aircraft operating in a 8.33 khz airspace Safety Scenario #2 25 khz VCS-equipped, exempt aircraft operating in 8.33 khz VCS airspace Safety Scenario #3 25 khz VCS-equipped, non-exempt aircraft operating in 25 khz VCS airspace close to the boundary with 8.33 khz VCS airspace. Safety Scenario #1 describes the normal operation in the 8.33 environment and applies indefinitely from the beginning of the airspace conversion to 8.33 khz VCS, in the area of applicability defined in IR annex I [16]. It is used to address the problem that an 8.33 khz equipped aircraft could encounter in an 8.33 khz sector due to the mistuning of the assigned frequency. Safety Scenario #2 addresses the (legitimate) presence of 25 khz VCS-equipped, exempt aircraft in 8.33 khz VCS airspace. Such aircraft are likely to exist for many years, even after 31 December Therefore, this Safety Scenario applies: to 8.33 khz VCS airspace in the area of applicability defined in IR Annex I; to 8.33 khz VCS airspace in the IR applicability area 11, from the start of the transition period of the Final Phase; thereafter, in the IR applicability area, until all non-8.33 khz VCS, exempt aircraft have been either retrofitted to 8.33 khz VCS or eventually withdrawn from service. 10 Articles 5(9) and 5(10) of the IR allows this situation to exist even after 2025 as some exemptions are open. 11 ICAO EUR Region where EU Member States are responsible for the provision of air traffic services 17

18 Safety Scenario #3 applies in the IR applicability area 12 due to some airspace and/or individual sectors being converted to 8.33 khz VCS before 31 December It applies therefore: in the area of applicability defined in IR Annex I during the Interim Phase in the IR applicability area, due to the fact that States with a particular serious frequency congestion problem are permitted to convert sectors to 8.33 khz before the 1 January 2018 (target date for conversion of all installed ground and aircraft radios to 8.33 khz VCS). Safety Scenario #3 applies also at the boundary of the IR applicability area, as follows: as soon as any airspace /sector close to the boundary is converted to 8.33 khz VCS indefinitely thereafter, because conversion to 8.33 khz VCS in neighbouring States is outside the scope of the implementation These Safety Scenarios are next used to derive Safety Objectives and Safety Requirements for the success and failure cases. 5.2 Success Approach Table 1 lists the Safety Objectives derived from the success approach for the scenarios indicated. ID Safety Objective Scenario SO#1. SO#2. SO#3. SO#4. 25 khz VCS-equipped, non-exempt aircraft shall not be routed through 8.33 khz VCS airspace (except where this is unavoidable for overriding safety reasons) States shall ensure that provision is made for providing adequate air traffic services to exempt aircraft in 8.33 khz VCS States shall ensure that all frequency assignments, for the purposes of providing air traffic services to exempt and non-exempt aircraft, are made so as to avoid interference to 8.33 khz VCS and 25 khz VCS communications in, or from, proximate airspace Prior to entering a 8.33 khz sector,the flight crew shall select the correct 8.33 khz VCS frequency for the sector Table 1: Safety Objectives from the Success Approach #3 #2 #1, #2 and #3 #1 The Table 2 shows the Functional Safety Requirements for the system elements and the Safety Objectives from which they were derived. ID Functional Safety Requirement Parent SO SR#1 SR#2 SR#3 State AIPs (supported as necessary by NOTAMs) shall provide up-todate information to all Aircraft Operators and Flight Crew concerning the VCS requirements of the airspace for which the State is responsible Aircraft Operators and Flight Crew shall be made aware of the consequences of using 25 khz VCS radios in 8.33 khz VCS airspace unless specifically authorised (i.e. State aircraft) Aircraft Operators and Flight Crew of 25 khz VCS-equipped, nonexempt aircraft shall not submit Flight Plans that would take the aircraft through any part of 8.33 khz VCS airspace SO#1 SO#1 SO#1 12 ICAO EUR Region where EU Member States are responsible for the provision of air traffic services 18

19 SR#4 SR#5 SR#6 SR#7 SR#8 SR#9 SR#10 Aircraft Operators and Flight Crew shall ensure that the Flight Plan for any flights which pass through any part of the EUR Region indicates the VCS capability and status (exempt / non-exempt) of the aircraft concerned Controllers shall not route a 25 khz VCS-equipped, non-exempt aircraft through 8.33 khz VCS airspace unless there is an overriding safety reason for so doing and they apply published procedures covering this situation Controllers shall not accept a 25 khz VCS-equipped, non-exempt aircraft into an 8.33 khz VCS sector unless there is an overriding safety reason for so doing and they apply published procedures covering this situation Before handing over an aircraft to an 8.33 khz VCS sector, Controllers shall ensure that the receiving sector is advised of the VCS capability and status (exempt / non-exempt) of the aircraft concerned ANSPs shall develop and implement strategies to ensure the safe handling of (non-8.33 khz) exempt aircraft in 8.33 khz VCS airspace State s frequency assignment plan shall comply with EUR Frequency Management Manual ICAO EUR Doc 011 (2009) in order to ensure that any ATS assigned frequency does not interfere with other assigned frequencies and is free from harmful interference. Flight Crew shall be adequately trained in the use of the 8.33 khz radios SO#1 SO#1 SO#1 SO#1 SO#2 SO#3 SO#4 Table 2: Functional Safety Requirements from the Success Approach 5.3 Failure Approach The assessment considered both abnormal conditions in the operational environment (e.g. airport / or airspace closure requiring aircraft to be diverted) as well as failures within the comms services (e.g. operational errors). Table 3 illustrates the hazards identified, along with their operational effects. The table also illustrates the possible mitigation means that could be implemented to reduce the effects (or consequences) of the hazards and the severity of the consequences that the hazards may lead to. It must be noted that the severity allocated to the hazards is done at very general level, and may be influenced by the several parameters, specific to the local implementation, such as the traffic level in the sector, the operational environment, the particular system architecture etc. Therefore allocation of the severity should be re-evaluated during the local safety assessment. 19

20 20 ID Hazard Operational Effects Possible Mitigation of Effects Severity 13 Haz#1 A 25 khz VCS-equipped, nonexempt aircraft enters 8.33 khz VCS airspace failure of SO#1 Inability to communicate with 25 khz VCS aircraft and/or interference to communications with 8.33 khz VCS aircraft Try to establish communication on Mhz In case of serious interference to comms with other airspace users, try to contact 25 khz VCS aircraft on emergency frequency to stop the interfering transmissions (see SO#7 below) Cat 3 (possibly Cat 2 for interference if prolonged) Apply normal lost-comms procedures (see SO#5 below) Apply normal lost-comms procedures, plus emergency procedures when appropriate( see SO#6 below) Interception of the aircraft Haz#2 Inadequate provision of facilities / procedures for handling of exempt aircraft in 8.33 khz VCS sectors failure of SO#2 Inability to communicate with (and therefore provide ATS to) exempt aircraft Try to establish communication on Mhz Apply normal lost-comms procedures (see SO#5 below) Cat 3 (possibly 2 depending on the number of aircraft involved at one time) Haz#3 Electromagnetic Incompatibility between 8.33 khz VCS and 25 khz VCS frequencies failure of SO#3 Interference to communications with aircraft Reduction in communications performances In case of serious interference to comms with other airspace users, try to contact 25 khz VCS aircraft on emergency frequency to stop the interfering transmissions (see SO#7 below) Try to contact 25 khz VCS on emergency frequency, if appropriate. Cat 3 (possibly Cat 2 if serious and prolonged) Stop all transmission on this frequency and revert to a backup frequency Haz#4 Incorrect frequency selection by the Flight Crew of an 8.33 VCSequipped aircraft failure of SO#4 Loss of communications with the offending aircraft Apply normal lost-comms procedures (see SO#5 below) Cat 3 (possible Cat2 if serious and prolonged Table 3 Hazard Identification and Effect Analysis. 13 Based on the Severity Classification Scheme as defined in ESARR 4 [19]