FALBALA – Final Project Report - Eurocontrol | - Driving ... Final Project Report 15-07-2004 FALBALA/WP5/FPR/D Version 1.0 EUROCONTROL CARE/ASAS/Sofréavia/04-061 – FALBALA Project

FALBALA Final Project Report 15-07-2004 FALBALA/WP5/FPR/D Version 1.0

EUROCONTROL CARE/ASAS/Sofréavia/04-061 – FALBALA Project Page 1/51

FALBALA – Final Project Report

First Assessment of the operational Limitations, Benefits & Applicability for a List of package I AS applications

FALBALA Project

Drafted by: Beatrice Raynaud Authorised by: Thierry Arino on 15-07-04 ADDRESSEES: Francis Casaux (CARE/ASAS Manager), Mick Van Gool (CARE Manager), Bogdan Petricel (AGC Programme), Costas Tamvaclis (ADS Programme)

COPY TO: CENA, DFS, EEC, NATS, UoG & Sofréavia Participants.



RECORD OF CHANGES

Issue Date Detail of changes

0.1 25th May-2004 Document initialisation based on Project Progress Report dated April 2004

0.2 15th June 2004 Refined sections 3, 4 and 6 based on WP1, WP2 and WP4 final report, respectively

0.3 28th June 2004 Minor changes in all sections following partners comments, draft material about WP3 in section 4 and

proposed recommendations in section6

0.4 12th July 2004 Changes in all sections following comments from EUROCONTROL and partners,

additional material in section 5 following WP3 final report update, and

additional material in section 7 about project conclusions and dissemination forum

1.0 15th July 2004 Proposed first issue

IMPORTANT NOTE: ANY NEW VERSION SUPERSEDES THE PRECEDING VERSION, WHICH MUST BE DESTROYED OR CLEARLY MARKED ON THE FRONT PAGE WITH THE MENTION OBSOLETE VERSION



EXECUTIVE SUMMARY

E.1. Project overview

E.1.1. FALBALA stands for First Assessment of the operational Limitations, Benefits & Applicability for a List of package I AS applications. The project supported the validation of three selected Airborne Surveillance (AS) applications from Package I [1]:

• Enhanced Traffic Situational Awareness during flight operations (ATSA-AIRB),

• Enhanced Visual Separation on Approach (ATSA-VSA)1, and

• Enhanced Sequencing and Merging operations (ASPA-S&M).

E.1.2. It aimed at providing a better understanding of the current situation from both an airspace and an aircraft perspective through the analysis of European radar data recordings, and assessing the possible operational benefits brought by the AS applications under investigation.

E.1.3. The FALBALA project was conducted by a consortium of six organisations (CENA, DFS, EEC, NATS, UoG, and Sofréavia as project leader). The contribution of three major European ANS Providers, as well as the participation of three major European airlines, significantly helped in the successful performance of the project.

E.1.4. The project comes within the framework of the CARE/ASAS action. It is also of particular importance for the AGC and ADS Programmes and will support the EUROCONTROL CASCADE Programme charged with the validation / implementation of the applications included in Package I.

E.2. Current situation analysis – Airspace perspective

E.2.1. From an overall airspace perspective, the assessment of the current situation was focused on three high-density environments of the European Core Area in which maximum operational benefits could be expected, i.e.:

• the Paris TMA, including both Paris Charles de Gaulle and Orly airports,

• the London TMA, including both London Heathrow and Gatwick airports, and

• the Frankfurt TMA.

E.2.2. The analysis performed includes a qualitative assessment of the main arrival traffic characteristics observed within each TMA and Extended-TMA, as well as a quantitative assessment using representative operational indicators. This work took advantage from the preparatory radar data processing aimed at identifying typical arrival traffic patterns, as well as from the AIP and METAR information gathered to support the radar data processing and analysis. The analysis also benefited from the support of European ANS Provider representatives familiar with each environment.

1 This application was formerly named Enhanced Successive Visual Approaches (ATSA-SVA) within [1].



E.2.3. The qualitative analysis dealt with the runway use, the use of radar vectoring to optimise the runway capacity while merging the arrival flows, the use of holding patterns to delay aircraft, the ordering of aircraft in the landing sequences and the spacing between successive aircraft in an arrival sequence. Some of the traffic characteristics were also addressed from a quantitative perspective. This was particularly the case for the spacing between aircraft in each arrival flow. Finally, specific traffic characteristics relevant to each investigated TMA were also assessed. These includes the aircraft spacing at the Initial Approach Fixes (IAF) for the traffic inbound to the Paris airports, the use of holding patterns by the traffic inbound to the London airports and the use of the Clearance limits within Frankfurt.

E.2.4. This work provided a better understanding of the current situation within the Paris, London and Frankfurt TMAs. It has demonstrated that the arrival traffic patterns in the investigated TMAs are highly dependent on the ATC working practices developed to cope with the actual traffic demand and the airspace and airport constraints. In particular, different strategies seem to be applied for each airport of the three investigated TMAs to get maximum benefit from the available resources.

E.2.5. Consequently, the operational indicators measured in each environment are not directly comparable. They need to be interpreted taking into account the characteristics of each airspace and airport (in particular, the available runways), as well as the strategic actions (e.g. ATC organisation, standard procedures) set up by ATC to manage the air traffic flows inbound and outbound of these airports.

E.2.6. Finally, the analysis of the current situation, performed in the first phase of the FALBALA study, provided evidence that the applicability of the AS applications should be assessed in relationship with the current situation in each considered airspace taking into account their respective characteristics and constraints.

E.3. Current situation analysis – Aircraft perspective

E.3.1. From an aircraft-centred perspective, the assessment of the current situation dealt with the description of the traffic environment as seen by both IFR and VFR flights in the three investigated TMAs, as well as the European Core Area en-route environment. The work combined both quantitative and qualitative assessments of what a pilot could see on a traffic display using traffic samples derived from the European radar data recordings and assuming full ADS-B equipage.

E.3.2. The analysis dealt with the amount of the traffic information available in a given surveillance range and a given altitude band, and with the influence of various display modes. It addressed separately IFR and VFR operations, as well as the various phases of flight associated with the three ASAS applications under investigation. A specific analysis of the maximum number of surrounding traffic in the Northern Europe Area (i.e., apart from the Paris and London TMAs) was performed independently from the phase of flight.

E.3.3. It should be underlined that the FALBALA project was not to assess or propose a particular CDTI design, but to bring elements for consideration by the future CDTI designers. These elements should also help defining required performances of an Airborne Surveillance and Data Processing system in the European airspace.



E.3.4. The study has demonstrated that the link between the airspace traffic density and the density of traffic information on the CDTI is not as direct as expected. Therefore, it is not possible to rely only on an airspace absolute perspective: a study based upon the relative perspective (counting aircraft observed by each aircraft of interest along their trajectory) seems essential.

E.3.5. The study showed the sensitivity of the results to the quantity and the quality of the surveillance data used. The analysis of the maximum numbers of visible aircraft has also demonstrated the need for traffic filtering onboard the aircraft. For VFR flights, as the selected range values are small, a simple vertical filtering seems to be enough to allow for CDTI legibility. For IFR flights, a specific analysis would be required to determine if the required traffic filtering needs to be linked to the ASAS application or to the phase of flight. Indeed, the study already shows that a safety-oriented filter will be different from a situational awareness oriented filter.

E.3.6. Finally, the study supports the idea that the ATSA-AIRB application is likely to bring safety benefits for VFR flights.

E.4. Operational indicators, questionnaires and workshop

E.4.1. Operational indicators were defined at the start of the study to drive both the assessment of the current situation and the extrapolation of potential benefits. This was mainly the case when analysing the European radar data recordings from both the airspace and the aircraft perspectives, although effort was focused on a few of them. When performing the operational assessment of the AS applications, the operational indicators were actually used as background information.

E.4.2. This operational assessment was supported by the performance of operational interviews (through questionnaires) and an operational workshop. The purpose was to obtain expert opinion on the studied ASAS applications from operational representatives.

• There were eighteen questionnaire respondents from a mixture of operational staff, (pilots or controllers) and management staff (ATM & airline managers). The analysis shows some areas of strong common opinion, as well as some issues with very wide-ranging opinion. From the questionnaire responses, a set of key issues was identified for each of the three ASAS applications studied within FALBALA, which were used as starting points for the discussion at the workshop.

• The workshop itself was hosted by NATS at Heathrow Control Tower Building during March 2004. In all, twenty-six people attended the workshop. Topics of discussion included the operational applicability of each AS application, their technical requirements (e.g. level of onboard automation, use of intent information and required displayed information), as well as the nature of the operational benefits that can be expected.



E.4.3. For ASPA-S&M, it was felt that it would be highly feasible to implement the application in the Paris area, and even possible for London Gatwick. However it was considered unfeasible to implement such procedures for London Heathrow and Frankfurt due to the complexity of the airspace. The ASPA-S&M application was considered to increase efficiency due to the reduction in R/T and through more consistent aircraft spacing. It was uncertain whether the application would increase capacity. There was mixed opinion on the level of automation required, and the need for ADS-B intent data. As a consequence the impact of ASPA-S&M on pilot workload could not be determined.

E.4.4. The applicability of the ATSA-VSA application within core European airspace appears to be very limited. For airports that do not currently use visual separation on approach, there is unlikely to be a case to introduce Enhanced Visual Separation. The additional benefits of the use of the CDTI for visual acquisition was that it would allow pilots to better judge spacing and might allow visually separated approaches to be used when VMC minima are not met but still with permanent visual contact.

E.4.5. The ATSA-AIRB application was considered to give improved common situational awareness between pilot and ATC although it recognised that their perspectives of the traffic situation were different. It was felt there would be little affect on pilot or ATC workload. It was felt the largest benefit of the ATSA-AIRB application would be in remote airspace and not radar controlled airspace.

E.4.6. There were also some issues identified which are common to all applications. It was recognised that there is a need to know what will be the minimum avionics requirements for ASAS, and what level of aircraft equipage needs to be reached before the anticipated benefits can be gained. The need for clear operational requirements and procedures for use of ASAS was restated and the issue of cost of retro-fitting aircraft avionics was raised.

E.5. Assessment of possible operational benefits

E.5.1. Finally, an initial assessment of possible operational applicability, limitations and benefits was performed which took advantages of:

• the analysis of real-time experiment outcomes,

• the analysis of the current situation performed from both the airspace perspective and the aircraft perspective, and

• the outcomes of the FALBALA operational interviews and workshop, as well as the operational expertise of the European ANS Providers participating in the project.

E.5.2. For the ATSA-AIRB and ATSA-VSA applications, the results of the Cargo Airline Association’s (CAA) Ohio Valley Operations Evaluation (OpEval) performed in July 1999 at Wilmington, Ohio and 2000 at Louisville, Kentucky were reviewed.



E.5.3. In summary, the study concluded that there are potentially many benefits of sharing traffic information with flight crew via a CDTI if the clutter and head down time issues can be resolved. One of the few potential disadvantages identified may be a tendency for pilots to question or hesitate over controller instructions, although this is difficult to anticipate for real operations.

E.5.4. Further, it was highlighted that a CDTI could help in tasks such as visual acquisition, maintaining visual contact, gauging distance and closure rates during visual separation on approach. Therefore, it might be worthwhile to investigate why visual separation is so little used at major capacity-limited airports in Europe compared with the US.

E.5.5. A specific approach was defined to address the ASPA-S&M application, which took advantage of the availability of the CoSpace real-time experiments conducted by EEC. It consisted of a comparison of the generic environment used in the experiments and the three specific environments (in “conventional ATC”) described in the first step of the FALBALA study.

E.5.6. Hence, a set of key characteristics for initial assessement of applicability of ASPA-S&M in TMA and E-TMA has been defined, and assessed against each specific environment with the support of the ANSP representatives participating to the FALBALA study. Finally, the framework proposed for the radar data extrapolation was illustrated using one metric, i.e. the aircraft spacing in the arrival sequences.

E.5.7. However, the study highlighted that the assessment of benefits related to spacing at reference points was hardly feasible in the scope of the FALBALA study. To go a step further, it seems essential to determine the minimum applicable spacing for pairs of successive landings (e.g. considering wake vortex, runway type of operations, runway occupancy time) before benefit extrapolation.

E.5.8. Although challenging, the assessment of operational benefits from a generic environment should be continued to develop the trends already identified. Further, since it is not easy to derive conclusive benefits from a generic environment, it is also necessary to assess the benefits using experiments on specific environment.

E.6. Project results and dissemination

E.6.1. In conclusion, the FALBALA study has demonstrated that:

• the airspace and airport characteristics and the traffic demand should be considered when assessing operational applicability and benefits of AS applications envisaged for implementation.

• the radar data analysis is of particular interest to better understand the current situation and assess possible benefits within specific airspace and at various airports.

• operational benefits depend on the AS application and the operational environment.



E.6.2. Key elements of the FALBALA study were presented to European stakeholders and representatives of the operational community during a one-day dissemination forum. The forum was held on the 8th July 2004 in the premises of Eurocontrol Head-Quarters in Brussels.

E.6.3. During this dissemination forum, the synthetic and combined descriptions of ATM operations at major European airports was well received. Further, the need to assess the applicability and possible benefits of future ASAS operations in the context of various airspace characteristics was recognised.

E.6.4. Finally, although it was agreed that the conclusions of the FALBALA study should not be taken as definitive, it was mentioned that the initial assessment performed during the study using various sources (including not only feedback from operational experts, but also real-time simulation outcomes) allowed getting some confidence in the results.

E.7. Project recommendations

E.7.1. Based on the experience gained within the FALBALA study, it is recommended to enhance the evaluation process based on radar data extrapolation in order to support to the benefit assessment in relationship with specific European environments.

E.7.2. Further in-depth analysis of the benefits identified for the ASPA-S&M and ASPA-AIRB applications should be performed, taking into account the potential limitations due to ASAS and CDTI design options. Such analysis could well be supported by a range of activities including:

• enhanced benefit evaluation based on radar data extrapolation,

• development of test and validation experiments in various operational environments,

• design studies of appropriate airborne traffic information and level of automation,

• assessment of the level of aircraft ADS-B/ASAS equipage necessary to deliver benefit and the cost of avionics retrofit, and

• benefit analysis in comparison with alternative operational improvements.

E.7.3. With regard to the ATSA-VSA application, it is considered that an investigation of the differences in operations between United States and Europe, will support the assessment of the possible benefits.



TABLE OF CONTENTS

1. INTRODUCTION.........................................................................................................................11 1.1. OBJECTIVE AND SCOPE .......................................................................................................... 11 1.2. BACKGROUD AND CONTEXT .................................................................................................... 11

2. PROJECT OVERVIEW..............................................................................................................12 2.1. SCOPE AND PURPOSE ............................................................................................................ 12 2.2. PROJECT BREAKDOWN ........................................................................................................... 13 2.3. PROJECT PARTICIPANTS ......................................................................................................... 14

3. WP1 – CURRENT SITUATION ANALYSIS – AIRSPACE PERSPECTIVE.....................15 3.1. GENERAL .............................................................................................................................. 15 3.2. DATA GATHERING AND PROCESSING ........................................................................................ 15 3.3. RADAR DATA ANALYSIS AND ASSESSMENT OF THE CURRENT SITUATION ...................................... 16 3.4. MAIN SIMILARITIES AND DISCREPANCIES................................................................................... 18 3.5. MAIN ACHIEVEMENTS AND CONCLUSIONS ................................................................................. 19

4. WP2 – CURRENT SITUATION ANALYSIS – AIRCRAFT PERSPECTIVE .....................21 4.1. GENERAL .............................................................................................................................. 21 4.2. QUALITATIVE ASSESSMENT OF THE CURRENT SITUATION ........................................................... 21 4.3. QUANTITATIVE ASSESSMENT OF THE CURRENT SITUATION ......................................................... 22 4.4. MAIN ACHIEVEMENTS AND CONCLUSIONS ................................................................................. 25

5. WP4 – OPERATIONAL INDICATORS, INTERVIEWS AND WORKSHOP .....................27 5.1. GENERAL .............................................................................................................................. 27 5.2. OPERATIONAL INDICATORS ..................................................................................................... 27 5.3. OPERATIONAL INTERVIEWS ..................................................................................................... 28 5.4. OPERATIONAL WORKSHOP...................................................................................................... 29 5.5. MAIN ACHIEVEMENTS AND CONCLUSIONS ................................................................................. 30

6. WP3 – ASSESSMENT OF POSSIBLE OPERATIONAL BENEFITS................................33 6.1. GENERAL .............................................................................................................................. 33 6.2. ENHANCED TRAFFIC SITUATIONAL AWARENESS DURING FLIGHT OPERATIONS.............................. 33 6.3. ENHANCED VISUAL SEPARATION ON APPROACH....................................................................... 34 6.4. ENHANCED SEQUENCING AND MERGING .................................................................................. 36

7. WP5 – PROJECT RESULTS AND DISSEMINATION .........................................................40 7.1. SYNTHESIS OF RESULTS ......................................................................................................... 40 7.2. FINAL DISSEMINATION FORUM ................................................................................................. 43 7.3. MAIN ACHIEVEMENTS AND CONCLUSIONS ................................................................................. 45 7.4. RECOMMENDATIONS FOR FUTURE WORK.................................................................................. 46

8. REFERENCES ............................................................................................................................47

9. ACRONYMS ................................................................................................................................48

APPENDIX A: MAIN ISSUES DISCUSSED AT THE FALBALA DISSEMINATION FORUM .................................................................................................................................49



LIST OF TABLES

TABLE 1: DEFINITION OF THE THREE AS APPLICATIONS OF INTEREST......................................................... 12 TABLE 2: FLIGHT PHASES UNDER CONSIDERATION PER ASAS APPLICATION............................................... 12 TABLE 3: PERSPECTIVES UNDER CONSIDERATION PER ASAS APPLICATION ............................................... 13 TABLE 4: AVERAGE AND MAXIMUM NUMBER OF VISIBLE AIRCRAFT PER PHASE OF FLIGHT IN (ARC, NORMAL)

NAVIGATION DISPLAY MODE..................................................................................................... 25 TABLE 5: RELATED OBJECTIVES OF OPERATIONAL INDICATORS ................................................................. 27 TABLE 6: EXAMPLE OF A TYPICAL QUESTIONNAIRE ITEM............................................................................ 29 TABLE 7: SUMMARY OF OPERATIONAL QUESTIONNAIRE RESPONDENTS ...................................................... 29 TABLE 8: SUMMARY OF RESULTS FOR THE ATSA-AIRB APPLICATION........................................................ 41 TABLE 9: SUMMARY OF RESULTS FOR THE ATSA-VSA APPLICATION......................................................... 41 TABLE 10: SUMMARY OF RESULTS FOR THE ASPA-S&M APPLICATION ...................................................... 42

LIST OF FIGURES

FIGURE 1: ILLUSTRATION OF ARRIVAL TRAFFIC PATTERNS AT PARIS, LONDON AND FRANKFURT ................... 17 FIGURE 2: ILLUSTRATION OF ARRIVAL SPACING DISTRIBUTION AT PARIS, LONDON AND FRANKFURT............. 18 FIGURE 3: ILLUSTRATION OF COCKPIT TRAFFIC DISPLAYS AT PARIS, LONDON AND FRANKFURT.................... 22 FIGURE 4: MAXIMUM NUMBER OF DISPLAYED TRAFFIC ON BOARD CRUISING IFR FLIGHTS IN (ARC, NORMAL,

80NM) NAVIGATION DISPLAY MODE ......................................................................................... 23 FIGURE 5: MAXIMUM NUMBER OF VISIBLE AIRCRAFT IN NORTHERN EUROPE............................................... 24 FIGURE 6: ISSUES RELATED TO THE BENEFITS EXTRAPOLATION................................................................. 37



1. Introduction

1.1. Objective and scope

1.1.1. This report presents the objectives and outcomes of the FALBALA project: FALBALA stands for First Assessment of the operational Limitations, Benefits & Applicability for a List of package I AS applications.

1.1.2. The project lasted one year, from mid-July 2003 to mid-July 2004. Its first phase consisted of setting the foundations for a first assessment of the operational applicability and the benefits associated with some Airborne Surveillance (AS) applications included in Package I [1]. The second phase of the project consisted of getting feedback from the operations experts on, and performing an initial assessment of, the operational benefits and constraints related to the ASAS2 applications under investigation.

1.1.3. The project comes within the framework of the CARE/ASAS action. The main purpose of the CARE/ASAS action is to support the validation of a strategic line of action identified by the ATM2000+ strategy, in particular by establishing a common view of ASAS applications. The main issues include the feasibility and conditions of applicability of the concept.

1.1.4. The project is also of particular importance for the EUROCONTROL CASCADE Programme in charge of the validation / implementation of the applications included in Package I. The results of the project will contribute to the validation activity of Package I and to future Cost / Benefit Analysis work.

1.2. Backgroud and context

1.2.1. The use of ASAS is seen as a promising option in the future ATM concept to provide an increase in capacity and flight efficiency while enhancing flight safety. By exploiting advances in flight deck technologies, ASAS applications aim is to increase the flight deck’s involvement in the maintenance of a safe, orderly and efficient flow of air traffic.

1.2.2. As for any new ATM concept, the evolution to a mature ASAS environment must be conducted via a phased implementation. At all stages of this phased implementation, compatibility must be assured between current and future systems and procedures. In addition, potential benefits must be assessed to encourage aircraft equipage and operational use of ASAS applications.

1.2.3. The agreed packaging approach aims at the early implementation of some ASAS applications on a worldwide basis. Package I of GS/AS applications [1] is going to help focusing the energies required for the development of the appropriate operational / technical standards and equipment.

2 The Airborne Separation Assistance System (ASAS) is considered a major enabler of airborne Package I applications. Hence, AS and ASAS



2. Project overview

2.1. Scope and purpose

2.1.1. The FALBALA project supported the validation of three selected Airborne Surveillance applications from Package I:

• Enhanced Traffic Situational Awareness during flight operations (ATSA-AIRB);

• Enhanced Visual Separation on Approach (ATSA-VSA), formerly named3 Enhanced Successive Visual Approaches (ATS-SVA); and

• Enhanced Sequencing and Merging operations (ASPA-S&M).

2.1.2. As a reminder, the Package I definition [1] of the three AS applications of interest is provided in the following table:

AS application Short description

Enhanced traffic situational awareness during flight operations (ATSA-AIRB)

This application provides the flight crews with an “enhanced traffic situational awareness” irrespective of visual conditions. Additional data is provided to flight crews to supplement traffic information provided either by controllers or other flight crews. The objectives are to improve safety of flight and the efficiency of air traffic control. In all airspace, the flight crews will be better able to detect an unsafe situation.

Enhanced successive visual approaches (ATSA-SVA)

This application is an aid for the flight crews to perform successive visual approaches when they are responsible for maintaining visual separation from the aircraft they are following. The objectives are to perform successive visual approach procedures on a more regular basis to enhance the runway throughput, and to conduct safer operations especially in high-density areas.

Enhanced sequencing and merging operations(ASPA-S&M)

The objective is to redistribute tasks related to sequencing (e.g. in-trail following) and merging of traffic between the controllers and the flight crews. The controllers will be provided with a new set of instructions directing, for example, the flight crews to establish and to maintain a given time or distance from a designated aircraft. The flight crews will perform these new tasks using a suitable human-machine interface. The main expected benefit is increased controller availability, but increased capacity through better adherence to ATC separation minima is also expected especially in high-density areas.

Table 1: Definition of the three AS applications of interest

2.1.3. Depending on the ASAS application under investigation, the following flight phases were considered:

Flight phases AS application

Take-off Climb Cruise Descent Approach Final

ATSA-AIRB X X X X X X

ATSA-VSA X

ASPA-S&M X X X

Table 2: Flight phases under consideration per ASAS application

3 The Requirement Focus Group (RFG), in charge of the Package I harmonisation between US and Europe, recently agreed this renaminig to avoid any misunderstanding between visual separation and visual approach.



2.1.4. The assessment performed within the project considered two distinct perspectives:

• an airspace perspective: this perspective addresses traffic synchronisation aspects, i.e., the tactical establishment and maintenance of a safe, orderly and efficient flow of air traffic. This perspective encompasses the regulatory authority, the ANS provider and the aircraft operator perspectives; and

• an aircraft perspective: this perspective addresses airborne surveillance and traffic situational awareness aspects. This perspective is own aircraft-centred and it encompasses the flight crew perspective for both IFR and VFR flights.

Aircraft perspective AS application Airspace perspective

IFR VFR

ATSA-AIRB X X

ATSA-VSA X X

ASPA-S&M X X

Table 3: Perspectives under consideration per ASAS application

2.1.5. The project was based on sound and validated data. Hence, it aimed at:

• providing a better understanding of current situation through the analysis of European radar data recordings. From an airspace perspective, consideration was on three high-density environments of the European Core Area in which maximum operational benefits could be expected, i.e.:

the Paris TMA,

the London TMA, and

the Frankfurt TMA;

From an aircraft perspective, the European Core Area en-route environment, comprising France, Germany, UK and Maastricht en-route airspace was also considered.

• assessing the possible operational benefits brought by the AS applications under investigation; Both qualitative and quantitative assessments of the circumstances, in which, and the frequencies, with which, the applications can be used, and the operational benefits that would accrue, has been initiated.

2.2. Project breakdown

2.2.1. The work programme carried out within the project was organised into Work Packages (WP) with clearly defined objectives and deliverables [2]:

• WP1: Current situation analysis – Airspace perspective (Cf. section 3);

This analysis was focused on the arrival traffic patterns identified within European radar data recordings gathered at the start of the project.

• WP2: Current situation analysis – Aircraft perspective (Cf. section 4);

This analysis was focused on the characteristics, and possible limitations, of the enhanced traffic information as possibly displayed in the cockpit of both IFR and VFR flights within typical arrival and en-route traffic situations.



• WP3: Assessment of possible operational benefits (Cf. section 6);

This WP consisted of the analysis of the outcomes of existing relevant ASAS real-time simulations, and the comparative analysis between the current (as described in WP1 and WP2) and the future situations taking into account the WP4 outcomes about possible operational benefits.

• WP4: Operational interviews and workshop (Cf. section 5);

This WP first consisted of defining a set of operational indicators for use within the project. In a second phase, it consisted of the performance of ATC controller and pilot interviews, and in the organisation of an operational workshop, to get a better understanding of the operational benefits and constraints related to the three ASAS applications under investigation.

• WP5: Project management and results dissemination (Cf. section 7);

This WP consisted of the management of the FALBALA project and ensured a close co-ordination of the work between the project participants. It also consisted of the consolidation and the dissemination of the results obtained in the previous Work Packages.

2.2.2. The FALBALA project was composed of two main phases:

• Phase 1 (current situation) consisted in providing the foundations of the project by gathering and processing the radar data, by adapting the tools and by defining the metrics required for the successful performance of the project. The analysis of the current situation both for an airspace perspective and an aircraft perspective was part of this phase. It was mainly composed of WP1, WP2 and WP4;

• Phase 2 (extrapolation) provided a first assessment of the operational benefits of the three AS applications investigated. It also aimed at extrapolating the results of the current situation analysis and providing an assessment of possible operational improvements. It concluded in synthesising the work performed during the project, in developing a final report and organising a dissemination forum. It was mainly composed of WP3, WP4 and WP5.

2.2.3. WP4, which belonged to both phases, defined the operational indicators that supported the analysis of the current and future situation, and was supported by the operational workshop aiming at getting the operational community feedback for both pilot and ATC controller perspectives.

2.3. Project participants

2.3.1. The FALBALA study was conducted by a consortium of six organisations (CENA, DFS, EEC, NATS, UoG and Sofréavia) with a leading role for Sofréavia (ATM division, AAA skill unit). A dedicated Task Leader was identified for each work package. The approach taken and the nature of the work entailed a close co-ordination between the project participants and with the CARE/ASAS Manager.

2.3.2. In addition, three major European airlines, i.e. Air France, British Airways and Lufthansa also participated to the operational interviews and workshop aiming at getting their operational feedback during the performance of the project.



3. WP1 – Current situation analysis – Airspace perspective

3.1. General

3.1.1. Within WP1, focus has been on analysing the arrival traffic patterns identified within European radar data recordings gathered at the start of the project. This analysis includes a qualitative assessment of the main traffic characteristics observed within each TMA and Extended-TMA, as well as a quantitative assessment using representative operational indicators.

3.1.2. The WP1 final report [3] first describes the methodology and tools that supported the assessment of the current situation performed using European radar data recordings. It provides an overview of the arrival traffic patterns observed in each Extended-TMA, each TMA and at the major airports. It also presents the main similarities and discrepancies identified between the three investigated airspace.

3.1.3. Finally, it draws some general conclusions on the work performed and provides recommendations for future work. In particular, it is expected that assessment of the current situation performed in WP1 will help assessing the applicability of the investigated ASAS applications within the various considered airspace.

3.2. Data gathering and processing

3.2.1. The preliminary task conducted within WP1 consisted of the gathering of one month of radar data from the European Core Area. Relevant information that supported the analysis of the radar data recordings (e.g. associated METAR data and AIP data from each airspace) was also collected. This was ensured through the implication within the project of three major European ANS Providers and of EEC.

3.2.2. The gathered radar data were from various sources (i.e. Mono-pulse SSR, Radar Data Processing Systems and Mode S station). Initial radar data processing, common to all environments, was applied to get radar data in a common standard format (i.e. MADREC format) and to discard irrelevant tracks for the purpose of the FALBALA study. It should be noted that FALBALA is the first project dealing with the processing of such a significant amount of radar data for different environments and for the same period.

3.2.3. To support the identification of the relevant traffic “patterns” within the radar data recordings, further radar data processing was performed to extract and classify the tracks taking into account the airspace characteristics, i.e. the airports, the runways and the arrival procedures. In a nutshell, an innovative approach has been developed that consisted in associating a radar track to published procedure, the procedures being initially described using the ARINC 424 semantic in an XML format.



3.3. Radar data analysis and assessment of the current situation

3.3.1. The core work conducted in WP1 consisted of analysing the arrival traffic patterns extracted from the European radar data recordings for each of the three TMA under investigation, i.e. Paris, London and Frankfurt TMA. This analysis benefited from the support of European ANS Provider representatives familiar with each environment.

3.3.2. The analysis of the current situation included a qualitative assessment of the main traffic characteristics observed within each TMA and Extended-TMA (E-TMA), as well as a quantitative assessment using representative operational indicators. This work took advantage from the radar data processing performed previously, as well as from the AIP and METAR information gathered to support the radar data processing and analysis.

3.3.3. Separate and detailed analysis was made for each major airport, i.e. Paris Charles de Gaulle, Paris Orly, London Heathrow, London Gatwick and Frankfurt. The result of these analyses is described into three separate annexes of the WP1 final report [3], respectively for the Paris, London and Frankfurt TMA.

3.3.4. The analyses dealt with the runway use, the use of radar vectoring to optimise the runway capacity while merging the arrival flows, the use of holding patterns to delay aircraft, the ordering of aircraft in the landing sequences and the spacing between successive aircraft in an arrival sequence. This preliminary work was mainly focused on the understanding of each airspace structure, the local traffic demand and ATC practices used to handle traffic flows in the considered airspace.

3.3.5. The following figures illustrate arrival traffic patterns observed within the three TMAs under investigation, during a westerly landing configuration. These snapshots give an overview of the approach and final phases in the three major airports in Europe.

Paris (Charles De Gaulle) London (Heathrow)

Radar vectoring area



Frankfurt

Figure 1: Illustration of arrival traffic patterns at Paris, London and Frankfurt

3.3.6. In a second step, some of the traffic characteristics were also addressed from a quantitative perspective, i.e. with the computation of operational indicators over the period of radar data recordings used for the study or on selected days. This is particularly the case for the spacing between aircraft in each arrival flow (as illustrated in the following figures).

Paris CDG - Two pairs of parallel runways

020406080

<60

70-79

90-99

110-1

19

130-1

39

150-1

59

170-1

79

190-1

99

210-2

19

230-2

39

(s)

26L 26R 27L 27R

Specialised runways in the south for either

landings or departures,

and alternatively used

runways in the north for both landings and

departures

London Heathrow - Two parallel runways

020406080

100120

<60

70-79

90-99

110-1

19

130-1

39

150-1

59

170-1

79

190-1

99

210-2

19

230-2

39(s)

27L 27R

Specialised runways for landings, swapped

at around 3 pm for environmental

reasons



Frankfurt - Dependent parallel runways

020406080

<60

70-79

90-99

110-1

19

130-1

39

150-1

59

170-1

79

190-1

99

210-2

19

230-2

39

(s)

07L 07R

Dependent runways used for both landings and departures

Figure 2: Illustration of arrival spacing distribution at Paris, London and Frankfurt

3.3.7. Specific traffic characteristics relevant to each investigated TMA were also assessed. These includes the aircraft spacing at the Initial Approach Fixes (IAF) for the traffic inbound to the Paris airports, the use of holding patterns by the traffic inbound to the London airports and the use of the Clearance limits within Frankfurt.

3.4. Main similarities and discrepancies

3.4.1. Different strategies seem to be applied for each airport of the three investigated TMAs to get maximum benefit from the available resources. The main similarities and discrepancies between the three environments identified during the study include the following:

• The similar definition of a Terminal Control Area (i.e., a TMA) around the major airports with three or four main TMA entry points (which correspond to the initial fixes for arrival procedures), but the distinct airspace characteristics at each airport of the considered TMAs:

small terminal airspace around the London airports with IAFs close to the runways; two runways at Heathrow and only one runway in Gatwick.

medium terminal airspace around the Frankfurt airport; two dependent parallel runways and a third one with distinct orientation at the airport.

large terminal airspace around the Paris major airports with remote IAFs; Triple parallel approaches with some shared IAFs between airports; two set of close parallel runways at Paris CDG and two converging runways at Paris Orly.

• The similar use of direct routing in E-TMA to expedite arrival flights converging towards same IAF (when traffic density permits) and the same limited use of the Standard Arrival Routes (STAR), but the distinct use of approach procedures in TMA depending on ATC working practices:

no published approach procedures in London Radar Vectoring area;

use of initial approach procedures, followed by radar vectoring towards final approach procedures, in Paris;

use of RNAV procedures in Frankfurt including radar vectoring for integration on final approach.



• The existence of two, three or four distinct IAFs for major arrival flows towards distinct airports in London and Paris TMA (a part from a few exceptions), but the distinct operational use of the IAFs towards each airport depending on their proximity from the runway thresholds and the ATC working practices.

• The same definition of holding patterns typically at the IAF (or Clearance Limit in Frankfurt), but the distinct use of holding patterns depending on ATC practices, actual traffic demand and airspace constraints:

not typically used in Paris CDG and London Gatwick;

sometimes used in Paris Orly and Frankfurt;

typically used in London Heathrow.

• The similar use of radar vectoring to either expedite or delay the flights when building arrival sequences in E-TMA and when merging one or more arrival flows in both E-TMA and TMA, as well as the early radar vectoring similarly applied before the IAF in TMA (depending on the IAF proximity from the final approach axis), but the distinct traffic patterns observed in TMA depending on the airspace available and the applicable procedures:

“S-shaped” traffic patterns in London (for merging of arrival flights on final approach);

“Trombone”-like traffic patterns in Frankfurt (with long “downwind” legs of RNAV procedures);

combination of large “trombone” and “comb”-like traffic patterns in Paris (with pseudo-downwind legs and vectors towards base legs or final approach axis).

• The distinct use of the runways depending on the airport characteristics and constraints:

specialised runway for either landings or take-offs in London Heathrow, Paris Orly and Paris CDG south, and for departures only in Frankfurt;

runway used for both landings and take-offs in London Gatwick, Paris CDG north and Frankfurt parallel runways;

triple parallel approaches in Paris CDG approach (due Le Bourget proximity);

staggered landings on closed parallel runways in Frankfurt.

• The significant variations observed in the three TMAs with regard to the aircraft spacing between arrival flights depending on the runway use, the traffic demand (with more or less pressure on the landing runway) and the type of aircraft (and applicable Wake Vortex minima).

3.5. Main achievements and conclusions

3.5.1. The work conducted within WP1 provided a better understanding of the current situation within the Paris, London and Frankfurt TMAs. It has demonstrated that the arrival traffic patterns in the investigated TMAs are highly dependent on the ATC working practices and supporting tools developed to cope with the actual traffic demand and the airspace and airport constraints.



3.5.2. Consequently, the operational indicators measured in each environment are not directly comparable. They need to be interpreted taking into account the characteristics of each airspace and airport (in particular, the available runways), as well as the strategic actions (e.g. ATC organisation, standard procedures) set up by ATC to manage the air traffic flows inbound and outbound these airports.

Main conclusions and results

3.5.3. The analysis of the current situation performed within WP1 has concluded that:

• the airspace and airport characteristics and the actual traffic demand must be considered carefully when assessing the traffic patterns resulting from ATC practices,

• a more in-depth investigation of the current situation should be performed to better support the quantitative assessment of the possible benefits brought by any AS application, and

• the applicability of the AS applications envisaged for early implementation in Europe should be assessed in relationship with the current situation in each airspace taking into account their respective characteristics and constraints.

Hence, the analysis of the traffic patterns identified through the European radar data recordings should support the assessment of the operational applicability and the possible benefits brought by the AS applications under investigation.

Recommendations for future work

3.5.4. To get a more complete and detailed picture of the current situation, it could be envisaged that future work addresses the following items:

• the current situation to other major TMAs in Europe to identify any other traffic patterns resulting from different ATC methods;

• the consideration of additional data (like flight plan data with the actual aircraft type) in relationship with the European radar data recordings, in particular to correlate between the actual aircraft spacing and the radar wake vortex separation minima,

• the actual vertical profiles to assess the operational use of vertical separation between arrival flights converging towards the same merging point,

• the actual speed profiles to assess the actual use of speed control to establish and maintain the arrival sequences, and to correlate it to the vertical profiles,

• the interference between arrival and departure flights to assess the constraints that apply to the arrival and departure flows, and

• the relationship between the traffic density and complexity, and the actual aircraft spacing in the arrival sequences.

3.5.5. Finally, to support a detailed quantitative assessment of possible benefits brought by the AS applications, additional statistics could be performed on:

• the heading and speed changes during the establishment and maintenance of arrival flows of traffic, and

• the flight distance and duration during the descent, approach and final phases of flight could be assessed.



4. WP2 – Current situation analysis – Aircraft perspective

4.1. General

4.1.1. The assessment of the current situation performed within WP2 provided a description of the traffic environment as seen by both IFR and VFR flights in the three environments assessed in WP1, as well as in the en-route environment of core Europe. This work benefited from the European radar data processing performed in WP1, as well as from the AIP and METAR information gathered (cf. section 3.2).

4.1.2. The WP2 final report [4] combines both the quantitative and qualitative assessment, from an aircraft perspective, of the cockpit display of traffic information derived from the European radar data recordings. This work is expected to help define the required performance of an Airborne Surveillance and Data Processing system in European airspace.

4.1.3. Finally, WP2 also developed some AVI format films of CDTI animations, which supported discussions during the operational workshop (cf. section 5.2.2) about the possible benefits and constraints linked to the provision of airborne traffic information.

4.2. Qualitative assessment of the current situation

4.2.1. Initial work conducted within WP2 consisted in analysing what a pilot could see on a traffic display fed with traffic samples from the three TMAs under investigation. This initial analysis was mainly a qualitative assessment of the main airborne traffic information characteristics during typical scenarios. It addressed separately IFR and VFR operations, as well as the various phases of flight associated with the three ASAS applications under investigation.

4.2.2. This analysis used cockpit display facilities developed at CENA. These include an EFIS (Electronic Flight Information System) Control Panel, a Navigation Display (ND) combined with a Cockpit Display of Traffic Information (CDTI), and a Primary Flight Display, which can be customised to assess various display options like the Navigation Display mode, traffic display range, altitude band or symbology.

4.2.3. The following figures illustrate some typical scenarios analysed during the study. Various display modes (i.e. Rose and Arc modes), traffic display ranges and altitude bands are presented.



VFR traffic information at a GA airfield IFR holding pattern in London TMA

IFR Sequencing & Merging in Paris TMA IFR on RNAV procedure in Frankfurt TMA

Figure 3: Illustration of cockpit traffic displays at Paris, London and Frankfurt

4.2.4. It should be underlined that the FALBALA project was not assessing or proposing a particular CDTI design, but that it brought elements to be considered by the future CDTI designers.

4.3. Quantitative assessment of the current situation

4.3.1. The next step within WP2 consisted in performing a quantitative assessment of airborne traffic information characteristics seen on a cockpit display of both IFR and VFR flights in different phases of flight and different environments. In particular, distinct analysis was performed for IFR flights: in cruise phase of flight, along STARs towards Paris and London airports, along RNAV procedures towards Frankfurt airport, during initial approaches in Paris and along final approaches at major airports.



4.3.2. The amount of the traffic information available in a given surveillance range and a given altitude band have been analysed. Two methods of aggregation have been used to get statistics over samples of radar data recordings:

• the first one was based on the curvilinear abscises along the procedure followed by the aircraft of interest. This determined the quantity of traffic that could be seen by an aircraft of interest along a given procedure and depending on the curvilinear distance to a given fix.

• another one was based on the geographical position of the aircraft of interest and the split of the airspace into squares whose size depended on the considered phase of flight. This gave the number of traffic that could be seen by an aircraft of interest in this square during the amount of time that was processed.

4.3.3. The influence of the various display modes of this traffic information was evaluated using several days of radar data recordings. The results highlighted the need for specific traffic filtering, possibly depending on the phases of flight, to support enhanced traffic situational awareness during flight operations.

4.3.4. The following figure illustrates the maximum number of traffic displayed onboard an IFR flight in cruise phase, depending on its geographical position inside the European core area. The selected ND mode is Arc, with a 80 NM range and the normal TCAS relative altitude band, i.e. from –2700 feet to +2700 feet. These display options are the actual selections used for navigation purposes.

Figure 4: Maximum number of displayed traffic on board cruising IFR flights in (Arc, Normal, 80NM) navigation display mode



4.3.5. Using Maastricht radar data recordings, a specific analysis of the maximum number of surrounding traffic in the Northern Europe Area (i.e., apart from the Paris and London TMAs) was performed independently from the phase of flight, to help set up the maximum surveillance tracking requirements for an airborne surveillance system.

4.3.6. This graph shows the evolution of the maximum number of visible traffic in relation with the selected range. All the surrounding traffic (in the radar coverage) is taken in account for the aircraft of interest and the ranges are extended up to the maximum range actually used for the Navigation Display.

Figure 5: Maximum number of visible aircraft in Northern Europe

4.3.7. To set up the maximum surveillance requirements, only the Rose mode without any vertical selection (dark blue curve) is relevant. This curve does not follow the square progression of the radius. The maximum number is not directly linked with the covered surface. An almost linear extrapolation seems to be preferable to assess the maximum number of targets with higher range (y ≈ 0.005 2x + 1.2x + 0.7).

4.3.8. Actually, with the additional use of Gatwick and Paris-North radar data which cover the two most crowded TMAs, the analysis of the maximum targets for IFR flights in cruise phase shows a higher number of visible aircraft for ranges up to 80 NM than that measured with the Maastricht radar data alone. However, due to the two radar coverage limitations, it is not possible to assess this maximum number for ranges up to 160 NM as it is in the case of the Maastricht radar data.

4.3.9. The following table provides a synthesis of the average and maximum number of aircraft visible (obtained with an aggregation based on the geographical position of the own aircraft) to an aircraft in a specific phase of flight with a selected altitude filter of Normal ([-2700 ft; + 2700 ft]), in Arc mode. Similar synthesis is also provided in the WP2 final report [4] for the Rose mode.



Arc 10 20 40 80 160

Avg Max Avg Max Avg Max Avg Max Avg Max

VFR 1 17 2 21 7 39 12 81 16 84

CRUISE 0 11 0 15 1 31 3 49 12 59

STAR 0 13 1 15 2 31 6 49 12 61

RNAV 0 5 0 7 1 8 1 9 1 12

INI 0 7 1 10 3 28 7 41 10 54

RVA 1 8 4 19 8 34 13 47

ILS (*) 2 19 4 23 7 34

Table 4: Average and maximum number of visible aircraft per phase of flight in (Arc, Normal) navigation display mode

(*): The high maximum numbers of visible aircraft when on final approach, in particular for the small selected ranges, can be explained from the observation of radar tracks down to the ground on those airports where the radar station is located close to the runways.


4.4.1. The study experimented with the use of two different methods for the calculation of an average (and maximum) density of traffic information. The first idea – using a curvilinear abscise as a reference for comparison between two trajectories – only allowed measures on published procedures. Furthermore, the workload is high and the presentation/interpretation of the results is not obvious. The second idea – cumulating data in a geographic mosaic – is applicable on all aircraft and environment of interest and enables a user-friendly presentation of the results.

4.4.2. The combination of all the various modes of display (range, altitude band and display mode) already implies a large amount of figures. Taking into account that there are four radar environments and many phases of flight to study, the most difficult and time-consuming task was to identify the most relevant figures. This is an additional reason why curvilinear indicators were not exploited.

4.4.3. The study has demonstrated that the link between the airspace traffic density and the density of traffic information on the CDTI is not as direct as expected. Therefore, it is not possible to rely only on an airspace absolute perspective: a study based upon the relative perspective (counting aircraft observed by each aircraft of interest along their trajectory) seems essential.



4.4.4. The study also showed the sensitivity of the results to the amount of cumulated data and the quality of the surveillance data. Even without low traffic hours, the more data you cumulate, the lower the average numbers are and the higher the maximum numbers are. Further, the radar coverage quality in the lower altitude affects the statistical results around an airport, e.g., for aircraft on ILS approaches.

Main conclusions and results

4.4.5. From the analysis of the airborne traffic information characteristics simulated from the processed European radar data, the following conclusions can be drawn:

• the high value of maximum numbers of displayed aircraft within each display selections requires the use of an adequate filtering of irrelevant traffic. This is true even for the lowest ranges.

• for CDTI legibility, the maximum number of aircraft shown on the CDTI would have to be limited to about fifteen, as shown by the qualitative analysis,

• for VFR flights, as the selected range values are small, a simple vertical filtering seems to be sufficient,

• for VFR flights, the qualitative analysis shows that the ATSA-AIRB application is likely to bring safety benefits,

• for IFR flights, the qualitative analysis during TMA operations shows that a situational awareness oriented filter will be different to a filter for safety-related applications, and

• an airborne surveillance function would have to process at least 350 targets for a 160Nm circular range. This was only computed for Maastricht area and could be higher in London or Paris TMA.


4.4.6. Based on the previous conclusions, it is recommended that future work focus on the following items:

• a better knowledge of the actual use of the different ranges and modes by the flight crew in order to reduce the number of computed indicators,

• the computation of the standard deviation of the density of traffic information to enable a more in depth analysis than using only average and maximum values,

• the tuning of appropriate altitude band thresholds for VFR flights,

• a specific analysis to determine if the traffic filtering for IFR flights needs to be linked to the ASAS application or to the phase of flight. In particular, the suitability of a TCAS Alert-like filtering (with larger time thresholds than the TCAS ones) could be checked.

• a specific analysis focused on aircraft on the ground to determine their impact in the proximity of the airport.



5. WP4 – Operational indicators, interviews and workshop

5.1. General

5.1.1. Within WP4, the initial work consisted in defining a set of operational indicators to support a first assessment of the operational applicability and benefits associated with the three ASAS applications under investigation.

5.1.2. In the next step, the WP4 work consisted in the performance of operational interviews and the organisation of an operational workshop. The purpose of both the operational questionnaires and workshop was to obtain expert opinion on the studied ASAS applications from operational representatives. In this context, the WP1 and WP2 outcomes were used as background information.

5.1.3. The WP4 final report [6] includes a description of the operational indicators defined at the start of the project, an analysis of the answers to the operational questionnaires, and the report on the outcomes of the Operational Workshop organised during the project.

5.2. Operational indicators

5.2.1. In the context of the FALBALA study, an operational indicator is a metric that expresses a significant characteristic of the traffic in the considered airspace. Each operational indicator is associated with one or more validation objectives, i.e. its related objective(s) when used to assess the current or future situation.

Validation objectives Operational indicators

Formulation of the hypotheses, or operational characteristic, to be assessed

Metrics that are related to the validation objective(s) of interest

Table 5: Related objectives of operational indicators

5.2.2. From an airspace perspective, two distinct sets of operational indicators are proposed for both the TMA and the Extended-TMA airspace, which intend to reflect the various operations performed in each of these airspace.

• Within the Extended-TMA, focus is on merging arrival flows along various STARs towards the same IAF taking into account aircraft sequencing and spacing constraints. Furthermore, ATC needs to provide separation to all controlled aircraft in the area, including arrival flights, over-flights and departure flights.

• Within the TMA, focus is on dispatching the arrival flights from each IAF depending on their final destination, as well as merging arrival flows from various IAF towards the same runway. Further, these operations need to take into account landing rate and the constraints of aircraft separation minima.



5.2.3. Examples of these operational indicators include the landing rates, the spacing (in time or distance) between successive aircraft in sequence, the vertical separation between such aircraft and the cross-track distance from the closest STAR or approach procedure.

5.2.4. From an aircraft perspective, the proposed operational indicators relate either to the overall airborne traffic information for both IFR and VFR flights during all phases of flight, or to the airborne traffic information linked to one specific traffic of interest during IFR operations from the Top of Descent (TOD) until landing. Examples of these operational indicators include the number of surrounding traffic within different surveillance range, bearing sectors or relative altitude bands, and the relative distance of the surrounding traffic.

5.2.5. These operational indicators were defined at the start of the study to drive both the assessment of the current situation in WP1 and WP2, and the extrapolation of potential benefits within WP3. This was mainly the case when analysing the European radar data recordings from both the airspace (WP1) and the aircraft (WP2) perspective (cf. sections 3 and 4, respectively), although the efforts were focused on a few of them. Within WP3 and WP4, the operational indicators were actually used as background information when performing the operational assessment of potential benefits.

5.3. Operational interviews

5.3.1. Both pilot and controller questionnaires were designed assuming no prior knowledge of ASAS. To help participants answer the questions efficiently, a briefing paper and presentation were produced to support the questionnaire itself. These were supplied with the questionnaire to all participants. In many cases, face-to-face briefings were also given.

5.3.2. For each application questions were chosen to assess:

• the feasibility of using each application in the airspace of each expert, i.e. how easy or difficult would it be to implement the application in that airspace?

• the potential impact on Workload and more generally on Working Practices from introducing the application.

• the anticipated Benefits from each application. Where applications are seen as having particularly one type of benefit (e.g. Safety, or Capacity), questions were specific about the type of benefit. In other cases the type of benefit was left unspecified.

• other issues? The final question on each application was left deliberately open-ended to allow participants to raise any other, unanticipated issues.

5.3.3. The questions were phrased as a basic “multiple choice” selection with opportunity to add explanation and further issues as written comments. This style of questioning was intended to provide some framework for the answers received (for ease of analysis) while still leaving freedom for replies to cover unanticipated issues. Further, it was hoped that the use of multiple-choice questions would encourage as much participation as possible. An example of a typical question is shown hereafter:



Do you think Enhanced Sequencing and Merging could provide benefits (capacity/efficiency/safety) in the airspace you work with?

No / A Little / A Lot Which & Why?

Table 6: Example of a typical questionnaire item

5.3.4. As shown in the following table, the project received responses from ten ATC respondents and eight airline respondents. For each organisation, there was a mixture of operational staff, (pilots or controllers) and management staff (ATM & airline managers). In each organisation, at least some of the respondents had previous experience of ASAS projects.

Pilot Respondents ATC Respondents

Air France (AFR)

2 (management pilot & airline manager)

DFS 2 (Frankfurt controllers)

Lufthansa (DLH)

3 (Airline manager & pilots) NATS 4 (ATM managers & LTMA controller)

British Airways (BAW)

3 (joint response airline manager and management pilots)

DGAC 4 (ATM managers & Paris controllers)

Table 7: Summary of operational questionnaire respondents

5.3.5. The results of the interviews were compiled and analysed. The analysis showed some areas of strong common opinion, as well as some issues with very wide-ranging opinion. A set of key issues for each of the three ASAS applications studied within FALBALA was identified, which were used as starting points for the discussion at the workshop.

5.4. Operational workshop

5.4.1. The workshop was hosted by NATS at Heathrow Control Tower Building during March 2004. In all, twenty-six people attended the workshop. These were either the same people who had completed the questionnaires, or project partners.

5.4.2. The presence of three major European ANS Providers in the project as well as three major European airlines significantly helped in the effectiveness of the workshop. It promoted discussion and debate between airlines and ANSPs, and pilots and controllers. It also allowed specific clarification on questionnaire answers to be sought, as well as a sharing of different regional operating procedures.

5.4.3. The day was split into an initial overview of ASAS and Package 1 applications, followed by a separate presentation and discussion on each of the three FALBALA applications. In addition, Eurocontrol Experimental Centre staff presented the CoSpace project results. This was done to demonstrate how one project had solved some of the common issues that Sequencing And Merging operations raise.



5.4.4. The discussions were wide-ranging and identified many issues that need to be considered further. Topics of discussion included the followings:

• for the Enhanced Sequencing & Merging application, where is it applicable? Is it necessary to automate spacing onboard? Is it necessary to have Intent information? Could the benefits be achieved using other concepts like 4D navigation or RNAV?

• what is the added value of Enhanced Visual Separation on Approach? Could it be applied elsewhere than in Frankfurt, where visual separation is already in use? Is it beneficial in a single runway configuration?

• which benefits could be expected from Enhanced Traffic Situational Awareness during flight operations? Which traffic should be displayed? What is the required displayed information? What about TCAS display?

5.4.5. During the workshop, operational people restated the need for clear operational requirements and procedures for use of an ASAS. The cost issue of retrofitting aircraft avionics was raised. It was recognised that there is a need to know what will be the minimum avionics requirements for ASAS, and what level of aircraft equipage needs to be reached before the anticipated benefits can be gained.


5.5.1. Based on the results of the operational questionnaires and the subsequent workshop the following conclusions can be drawn:

Enhanced Traffic Situational Awareness during flight operations

5.5.2. The consensus between pilots and ATC was that the benefit of ATSA-AIRB would be an improved common situational awareness between ATC and the pilot, although it was recognised that the pilot’s perspective of the traffic situation is not the same as that of ATC. It was felt there would be little effect on either pilot or ATC workload.

5.5.3. It was felt that pilot situational awareness would improve safety through accurate position information, and would compensate for the loss of the ‘party-line’, caused by increasing use of data-link. However it was noted that to achieve this would require 100% equipage of ADS-B out within the airspace.

5.5.4. Finally it was recognised that the biggest benefit of ATSA-AIRB to the pilot would be in remote airspace, rather than in radar controlled airspace.

5.5.5. There was mixed opinion on what the CDTI should display and in what phase of flight or ASAS application. The issue of the integration of TCAS and ADS-B on the same display was also raised.

Enhanced Visual Separation on Approach

5.5.6. The applicability of the ATSA-VSA application within core European airspace appears to be very limited. For airports that do not currently use visual separation on approach, there is unlikely to be a case to introduce Enhanced Visual Separation.



• The Frankfurt example shows there are capacity benefits from visual separation where staggered approaches can be flown to closely spaced parallel runways.

• The potential benefit of using visual separation at single runway airports is not clear.

5.5.7. The additional benefits from use of the CDTI over visual approaches were considered to be that the CDTI could improve the safety of operations by an enhanced visual acquisition and could allow pilots to better judge the spacing. It could allow visually separated approaches to be used more often when VMC minima are not met but still with permanent visual contact. The true value of this benefit could not be determined.

5.5.8. It is possible that the use of visually separated approaches might lead to pilots using greater spacing than is currently achieved by radar controllers, hence reducing capacity.

Enhanced Sequencing & Merging

5.5.9. It was felt that it would be highly feasible to implement ASPA-S&M in the Paris area, and even possible for London Gatwick. However it was considered unfeasible to implement such procedures for London Heathrow and Frankfurt due to the complexity of the airspace.

5.5.10. It was also felt that the application should be integrated with an arrival manager tool to help sequence the aircraft. RNAV routing was not seen as impacting on the ASPA-S&M application4. It was unclear what the impact might be on adjacent en-route airspace. It was agreed that time based spacing is a necessary precursor to effective ASPA-S&M. However, it was unclear whether ASPA-S&M would deliver significant additional benefit over time-based spacing by ATC.

5.5.11. There was some reservation on the level of automation required, and the need for ADS-B intent data, to allow the pilot to achieve the delegated spacing. The CoSpace experiment developed a concept that indicated the Package 1 application could be achievable with no intent data and minimal avionics impact. Others suggest that a fuller integration between intent data, the FMS, and autopilot will be required.

5.5.12. There was agreement that ASPA-S&M application would improve ATC efficiency through reduced R/T, establishing the sequence further out, and more consistent spacing. There was less certainty on whether the application would deliver a capacity increase, as the airports in question are already highly utilised. It was felt that pilot workload would largely depend on the level of cockpit automation.

5.5.13. There was some concern over the consequence of de-skilling ATC and on the effect of system or sequence breakdown. There was also a question on the level of equipage necessary to achieve any benefits.

4 DFS will be trialling S&M with RNAV routes in simulations for the EUROCONTROL CASCADE programme by end of 2004.




5.5.14. Based on the results of the workshop and questionnaires, recommendations have been drawn up by the Work Package 4 project team to identify clear follow-on actions. It should be made clear that these recommendations were not the direct output of the workshop or interviews.

5.5.15. The results on ASPA-S&M suggest the application is feasible and could provide benefit for some TMA areas. It is recommended that more detailed study is undertaken for these TMA areas to assess how the ASPA-S&M could be implemented and what the benefits would be. It is also recommended to develop experiments:

• to test abnormal situations, such as the consequences of system or sequence breakdown at high workload instances;

• to combine ASPA-S&M with arrival management tools;

• to compare the benefits of ASPA-S&M (with time based spacing) with the benefits of time based spacing provided by ATC, possibly in an RNAV approach environment;

• to assess the level of aircraft equipage which is necessary to deliver benefit.

5.5.16. Based on the conclusions for ATSA-VSA, the application appears to offer benefits for only a limited number of airports, such as Frankfurt. It should therefore be considered with regard to specific airports and not for general use.

5.5.17. Based on the conclusions for ATSA-AIRB it is recommended that effort is spent addressing the design criteria of a CDTI. In particular, there should be studies:

• to assess whether and how ADS-B traffic information and TCAS traffic and resolution advisories can be combined on the same display.

• to develop appropriate filtering algorithms for the CDTI, allowing a single CDTI to be used with different ASAS applications, during different phases of flight and in different types of airspace.



6. WP3 – Assessment of possible operational benefits

6.1. General

6.1.1. The general approach to WP3 consisted of identifying relevant operational indicators based on the analysis of real-time experiment outcomes, and then extrapolating the anticipated benefits and constraints taking advantage of the assessment of the current situation within the FALBALA study.

6.1.2. Because of the FALBALA resources and timescale constraints, the benefit assessment to be performed on each ASAS application of interest was not done at a detailed level. Furthermore, a distinct approach was used for the each of the three AS applications under investigation, reflecting their level of maturity and the operational interest in them.

6.1.3. The WP3 final report [5] provides an overview of the benefits of each application, and a path for a more comprehensive assessment. This work benefited from the outcomes of the WP4 operational interviews and workshop, as well as the operational expertise of the European ANS Providers participating in the project.

6.2. Enhanced Traffic situational Awareness during flight operations

Real-time experiment outcomes analysis

6.2.1. The results of the Cargo Airline Association’s (CAA) Ohio Valley Operations Evaluation (OpEval) performed in July 1999 at Wilmington and October 2000 at Louisville, Kentucky were reviewed [9]. During OpEval, twelve aircraft operated by three member airlines of the CAA flew an intensive series of flight trials providing a basis for evaluating near term CDTI applications and data-link technologies. The flight test was accomplished in partnership with the FAA’s Safe Flight 21 program, the MITRE Center for Advanced Aviation System Development, NASA, DoD and other industry and academic partners.

6.2.2. In particular, the human factors results of the OpEval flight trials consisted of a collection of positive statements of benefit (statistically quantified where possible) covering a range of aspects relating to the applications under study.

• From the ATC perspective, the controllers indicated that CDTI had a slight positive effect on providing control information. One comment was that the use of CDTI allowed the controller to call traffic earlier than normal, thus making better use of the controller’s time. The controllers also indicated that the use of CDTI had a moderately positive effect on communicating.

• From an airborne situational awareness perspective, the flight crews rated various CDTI features (e.g. the flight ID data tags, the altitude information on the display and the additional information provided in the selected target block) against their usefulness and their easy understanding. During ILS approaches (visibility < 5 NM), the CDTI increased flight crew confidence in their ability to maintain an awareness of the exact position of traffic, even when traffic transitioned in and out of obscurations. Finally, the flight crew commented that the CDTI aided in planning and workload management and intra-cockpit communication.



Limitations and applicability assessment

6.2.3. Based on the FALBALA operational workshop outcomes (WP4), and the current situation analysis from both the airspace perspective (WP1) and the aircraft perspective (WP2), the main limitations and applicability of the previous results to Europe were assessed within WP3 as follows: • partial awareness due to partial equipage may be an issue [Workshop]; • display clutter may be an issue particularly in high density airspace [WP2]; • for the CDTI legibility, the maximum number of aircraft shown on the CDTI

would have to be limited to about fifteen, as shown by the qualitative analysis [WP2];

• pilots may question ATC instructions and hesitate before complying [Workshop];

• the analysis of number of targets typically displayed in the European regions London TMA, Paris TMA, Frankfurt TMA and Maastricht en-route indicate that CDTI clutter is a serious issue for many phases of flight [WP2];

• there are differing views on which aircraft should be displayed on the CDTI. The CDTI requirements vary between applications. Partly it may depend on the flight crew preferences [Workshop]. Further, when considering CDTI design, the ASAS applications cannot be looked at independently. They must be taken together.

Main conclusions and recommendations

6.2.4. In summary, there are potentially many benefits of sharing traffic information with flight crew via a CDTI if the clutter and head down time issues can be resolved.

6.2.5. One of the few potential disadvantages identified may be that there is more of a tendency for pilots to question or hesitate over controller instructions but this is difficult to evaluate by experiment because the sense and judgment of risk is not the same as in real operations.

6.2.6. It is recommended to study CDTI clutter issue to see how best to filter traffic to an acceptable level.

6.3. Enhanced Visual Separation on Approach


6.3.1. Results anticipated from NUPII related to the ATSA-VSA application were not available so related results from the OpEval were used instead. The OpEval enhanced visual approach application was intended to augment a normal visual approach by providing additional traffic information that was intended to aid flight crews in visually acquiring proximate traffic, and increasing overall traffic awareness.

6.3.2. With regard to potential ATC benefits, the CDTI allowed flight crew to recheck the position of traffic without requesting this information from ATC; a potential reduction in workload for both the flight crew and ATC. Controllers indicated that CDTI had a positive effect on maintaining a safe and efficient traffic flow, as well as on providing control information (e.g. the controllers felt more certain that flight crews were following the correct traffic, and pilots were better able to maintain their own spacing).



6.3.3. With regard to potential airborne benefits, flight crew members rated the CDTI as aiding them significantly in visually acquiring traffic, before and after an ATC traffic call. They also reported that maintaining an awareness of multiple traffic targets was less difficult when using the CDTI. There was indeed a good match between the physical location of traffic, ATC reported traffic position, and CDTI traffic position.

6.3.4. The majority of flight crew commented that CDTI helped during visual approaches. It allowed to tighten up the approach; it was very useful for acquiring and re-acquisition of traffic, the display of ground speed and distance information reduced the workload of following traffic; it increased situational awareness in busy visual traffic pattern; it supported re-checking the position of traffic without consulting ATC; It improved the pilots’ awareness of ATC traffic pattern objectives; It improved with experience – for example, the pilots’ confidence in maintaining visual separation during the approach.


6.3.5. Based on the FALBALA operational workshop outcomes (WP4), and the current situation analysis in the investigated TMAs (WP1 & WP2), the main limitations and applicability of the previous results to Europe were assessed within WP3 as follows: • display clutter may be an issue in high density airspace [Workshop]; • flight crew rated head down time as being an issue during visual acquisition.

The CDTIs were separate boxes not integrated with the navigation display [OpEval];

• frequency of use depends on percentage of aircraft equipped; • it was pointed out that in the US it is standard practice to fly successive visual

approaches to single and parallel runway airports. However this is not the case in Europe. Successive visual approaches are not often flown at major capacity-limited airports because of the increased risk of missed approaches [Workshop];

• the Frankfurt example shows there are capacity benefits from visual separation where staggered approaches can be flown to closely spaced runways [Workshop];

• it was suggested that with the continuing growth in traffic levels, system capacity is being reached and there is a need to use it as efficiently as possible. The use of CDTI might support this without compromising safety. [Workshop];

• it was suggested that the use of the CDTI might allow visually separated approaches to be performed more frequently at Frankfurt. This might result in the visual meteorological condition minima for such approaches applicable today (e.g. cloud ceiling, visibility) being reviewed [Workshop];

• for airports at which there is not already a case to use visual separation on approach, there is unlikely to be a case to introduce enhanced visual separation on approach [Workshop];

• for Frankfurt RNAV procedures, many of the figures for maximum number of targets on the CDTI at one time are close to the ‘limit’ of fifteen [WP2];

• perhaps for visual acquisition and vertical separation on approach a simple solution to the clutter problem would be to only display the one target in front as in the CoSpace project.




6.3.6. Visual separation is currently used in Frankfurt TMA and results from trials in the US imply that a CDTI could help in tasks such as visual acquisition, maintaining visual contact, gauging distance and closure rates.

6.3.7. Visual separation is not used in London or Paris TMAs so there is unlikely to be a case to introduce enhanced visual separation.

6.3.8. From the WP2 airborne perspective analysis, it is recommended to investigate how pilots judge wake vortices in successive visual approach situations and how could CDTI help.

6.3.9. It is recommended to investigate why visual separation is so little used in Europe compared with the US. The reason given during the workshop was because of the increased risk of missed approaches but why should this not be the case in the US as well.

6.4. Enhanced sequencing and Merging


6.4.1. When analysing existing relevant real-time experiments for the Enhanced Sequencing and Merging application, CoSpace (in collaboration with NUPII, COOPATS tiger team), was considered among others (such as EC MFF, NASA DAG-TM) as it covers both Extended-TMA and TMA, with both controller and flight deck perspectives [7], [8].

6.4.2. When properly used – i.e. fitting in with current sequencing practices – the CoSpace experiments suggest that spacing instructions seem to be beneficial in Extended-TMA (increased controller availability and better stability of flows transferred to TMA). In contrast, it was observed that improper use can lead to much degraded situations (increased controller workload). Though implying significant changes as compared to today, the spacing instructions developed for Extended-TMA seem to be also usable in TMA, in particular for the integration onto final approach of flows under airborne spacing instructions. Recent experiment showed that airborne spacing tends to reduce the amount of late vectoring and encourage earlier flow integration in TMA. With airborne spacing, the inter aircraft spacing on final is more regular and trajectories are straighter.

6.4.3. As shown in the following figure, a specific approach has been defined to address the ASPA-S&M, which takes advantage of the availability of the CoSpace (and the former EACAC) real-time simulations conducted by EEC. It consists in the following steps:

• a comparison of the real-time generic environment under the two conditions (in “conventional ATC” and “with ASAS spacing”) and the three specific environment (in “conventional ATC”) described in WP1;

• the answer to the question: “Is spacing applicable in the specific environment taking into account the airspace characteristics?”; Key characteristics that would support the use of S&M include the use of sequencing constraints before the aircraft transfer to the TMA and specific TMA design; and



• the extrapolation of the benefits for each specific environment using the results of the application of ASAS spacing in the generic environment. Only benefits related to metrics that can be computed with radar data were used. All the benefits related to the impact on human activity (e.g. increased availability and more anticipation) could not directly be assessed in the FALBALA study.

6.4.4. In a simple manner, considering one given metric, potential benefits can be assessed by determining its value in the specific environment. If this metric is “similar” to the one of the generic environment in “conventional ATC”, there could be potential benefits from the use of “ASAS spacing”. Further, no potential benefits are anticipated if it is already “similar” to the one “with ASAS spacing”.

6.4.5. However, as illustrated in Figure 6, two major issues have been identified. Firstly, how to assess the impact, on the metrics considered, of the differences between the generic and each specific environment? Secondly, how to assess the impact, on the metrics considered, of the limitation of use of S&M resulting from constraints of each specific environment?.

GenericConventional ATC

GenericWith ASAS spacing

SpecificConventional ATC

SpecificWith ASAS spacing

Comparableenvironment?

Limitationof use?

Results of experiments

Extrapolatingbenefits?

KnownUnknown

GenericConventional ATC

GenericWith ASAS spacing

SpecificConventional ATC

SpecificWith ASAS spacing

Comparableenvironment?

Limitationof use?

Results of experiments

Extrapolatingbenefits?

KnownUnknown

Figure 6: Issues related to the benefits extrapolation


6.4.6. A set of key characteristics for initial assessement of applicability of S&M in TMA and E-TMA has been defined, which reflects the current knowledge obtained through the CoSpace real-time experiments.

• For the TMA, the constraints related to airspace essentially rely on the possibility to place standard trajectories with holding legs converging to a unique merging point. To provide the required anticipation, it seems necessary to group the arrival control positions (per runway) into one, and to man this unique position with an executive and a planning controller. Assuming at this stage full equipage, another key characteristic is the traffic level.



• For the E-TMA, a key characteristic is the presence of a sequencing constraint at a point before transfer to TMA (e.g. imposed by a letter of agreement between TMA and E-TMA). If no sequencing constraint is needed, S&M could be used but is not necessary. To avoid extra coordination with the sequencing (downstream) sector when initiating S&M in a pre-sequencing (upstream) sector, it is recommended to group these two types of sectors (provided that traffic allows for it).

6.4.7. To help assess the potential for applying ASPA-S&M in core Europe, the ANSP representatives participating to the FALBALA study assessed the constraints described previously, in the context of their respective environment. From the analysis of this assessment, the following points came out:

• for Paris and CDG in particular, the main difference with the generic (CoSpace) environment essentially relies on potentially 3 IAFs feeding a runway. This should not constitute a blocking point;

• for London Heathrow, size of TMA is small, with 4 IAF potentially feeding one runway, stacks are used on a routine basis and traffic is not pre-sequenced. These characteristics seem hardly compatible with the use of S&M;

• for London Gatwick, size of TMA is smaller than the generic environment and 3 IAF are feeding the runway. However, traffic seems to arrive smoothly (as suggested by the “exceptional” use of stacks). Space seems available to place “holding legs”. All this should allow the use of S&M; and

• for Frankfurt, although there are 4 IAFs, the size of the TMA, the pre-sequencing of traffic and the possibility to place “holding legs” suggest that S&M would be compatible.

6.4.8. was consistent with the WP4 outcomes (cf. section 5) apart from the applicability to Frankfurt, which seems to contradict the operational feedback from the interviews and the operational workshop.

Radar data measurements extrapolation

6.4.9. Concerning the benefits analysis, the framework proposed for the radar data extrapolation was illustrated using one metric of interest, which was the spacing between successive aircraft in the arrival sequences in TMA and E-TMA.

6.4.10. To make a relevant comparison between the generic environment defined within the CoSpace experiment and the Paris, London, Frankfurt environments in “conventional ATC”, the reference point (where the spacing is measured) should have been similar. Further, the actual spacing should have been related to the required spacing and to the traffic level.

6.4.11. Indeed, data available did not allow for knowing if a large spacing corresponds to a required spacing (e.g. for wake vortex, departure, runway inspection), a gap in the sequence or an inefficient sequencing; and similarly, if a small spacing corresponds to a visual separation, a tight (but controlled) sequencing due to a high traffic load or a missed sequencing.

6.4.12. Hence, the study highlighted that the assessment of benefits related to spacing at reference points seemed hardly feasible at this stage.




6.4.13. The applicability analysis was based on CoSpace assumptions and findings, the feedback collected from the ANSPs participating in the study and on WP1 and WP4 outcomes. It enables to build an initial understanding of applicability of S&M to TMA and E-TMA. Considering existing airspace structure, Paris (CDG and Orly) is well suited to the use of S&M, as well as London Gatwick. Applicability to London Heathrow seems hardly feasible in today’s operations (limited airspace and use of holding stacks). For Frankfurt, although some indicators would suggest potential applicability, discussions from WP4 tend to conclude that applicability is hardly feasible.

6.4.14. Concerning the benefits analysis, a specific approach has been proposed. As an illustration, the application of one metric (i.e. the spacing at a reference point) on each environment was presented. However, this highlighted that the assessment of benefits related to spacing at reference points was hardly feasible in the scope of the FALBALA study. To go a step further, it seems essential to determine the minimum applicable spacing for pairs of successive landings (e.g. considering wake vortex, runway type of operations, runway occupancy time) before benefit extrapolation.

6.4.15. The CoSpace experiments suggest that S&M could provide other ATC effectiveness benefits, typically in terms of flight efficiency (e.g. shorter trajectories, number of trajectory changes). It would be worthwhile to assess the associated metrics within radar data to enhance the benefit evaluation.

6.4.16. As observed in the CoSpace experiments and as mentioned in WP4, S&M could provide benefits in terms of human activity (e.g. increased availability, more anticipation). It was beyond the scope of the FALBALA study to assess these additional benefits.

6.4.17. Although challenging, the assessment of operational benefits from a generic environment should be continued to develop the trends already identified. Further, since it is not easy to derive conclusive benefits from a generic environment, it is necessary to assess the benefits using experiments on specific environment.



7. WP5 – Project results and dissemination

7.1. Synthesis of results

7.1.1. In a first step, the FALBALA study has performed an assessment of the traffic patterns within three high-density environments of the European Core Area, i.e., Paris, London and Frankfurt area, in which maximum benefits could be expected from an ATC perspective. From an aircraft perspective, the European Core Area en-route environment was also considered when assessing the airborne traffic information characteristics possibly displayed on a CDTI. Apart from the benefits extrapolation performed for the ASPA-S&M application, the WP1 and WP2 outcomes were mainly used as background information within the next step of the study.

7.1.2. In this second step, an initial assessment of the operational benefits and limitations of three ASAS applications was conducted, which main outcomes are summarised in the tables below. This assessment was undertaken using various sources of information for which distinct analysis was performed including:

• an analysis of real-time simulation results (as part of WP3);

• an extrapolation of the real-time simulation results using the actual radar data measurements in each considered airspace (only performed for the ASPA-S&M application, as part of WP3 and using WP1 outcomes);

• an analysis of the pilot and controller interviews (as part of WP4);

• an analysis of the operational workshop outcome (as part of WP4). Since the main interview outcomes were restated during the workshop, only the additional outcomes from the workshop are reported hereafter; and

• an assessment of the applicability and limitations of the ASAS applications (as part of WP3, using the WP1, WP2 and WP4 outcomes).

Initial benefits and limitations assessment

Enhanced Traffic Situational Awareness during flight operations (ATSA-AIRB)

Analysis of real-time simulation results

Increased flight crew confidence in their ability to maintain an awareness of the exact position of traffic Pilots’ aid in planning and workload management and intra-cockpit communication Slight positive effect on providing control information

Pilot and controller interviews outcome

Generally ‘a little’ to ‘a lot’ of benefits, mainly safety benefits Most benefits expected in remote areas (rather than radar controlled airspace) Pilot’s workload depends on design options Possible ATC workload increase (due to pilots’ queries) Main concern about partial ‘ADS-B out’ equipage




Enhanced Traffic Situational Awareness during flight operations (ATSA-AIRB)

Operational workshop outcomes

Benefits of shared views between controller and pilot not easy to quantify Expectation for TCAS/ADS-B information on same display on board CDTI requirements vary between ASAS applications

Applicability and limitations assessment

Potentially many benefits of CDTI, if the clutter and head down time issues can be resolved Potential disadvantages related to a possibility for pilots to question or hesitate over controller instructions

Table 8: Summary of results for the ATSA-AIRB application

7.1.3. In complement to the assessment reported above which is related to the WP3 and WP4 results, it should be noted that the qualitative analysis of airborne traffic information characteristics performed in WP2 has shown that ATSA-AIRB application is likely to bring safety benefits to VFR flights.


Enhanced Visual Separation on Approach (ATSA-VSA)


Positive effect on maintaining a safe and efficient traffic flow Increased pilots’ awareness, aid to visual acquisition and better ability to maintain their own spacing Potential reduction in workload for both the flight crew and ATC

Pilots’ and controllers’ interview outcomes

Wide-ranging opinions on feasibility and benefits, depending on the airport; Clear capacity benefits at Frankfurt Possible reduction in pilots’ and controllers’ workload, but not agreed by all


Airport configuration critical to potential benefits from visual separation Capacity benefits with staggered approaches to dependent parallel runways (like in Frankfurt), but unclear benefits at single runway airports Additional safety benefits and increased applicability from the use of CDTI Use of CDTI might lead to greater spacing than that currently achieved by radar controllers Unlikely to be a case at airports where there is not already a case to use visual separation on approach Could provide benefits during successive visual approaches in Nice


CDTI assistance for visual acquisition, maintaining visual contact, gauging distance and closure rates Unlikely to be a case to introduce enhanced visual separation in London or Paris

Table 9: Summary of results for the ATSA-VSA application

7.1.4. Taking into account the different views highlighted in WP3 and WP4 about the possible benefits of the ATSA-VSA application, it might be worthwhile to investigate the difference in operations between US and Europe.




Enhanced Sequencing & Merging (ASPA-S&M)


Increased controllers’ availability and more anticipation in the sequence building in E-TMA Better stability of flows transferred at the TMA, with more aircraft getting the optimal spacing value Usable in TMA, in particular for the integration onto final approach of flows Improper use can lead to much degraded situations (increased controller workload) With appropriate assistance to contain pilots’ workload, better understanding of the situation and gain in anticipation

Pilots’ and controllers’ interview outcomes

Wide-ranging opinions on feasibility, depending on the airport Some anticipate capacity and efficiency benefits, other don’t Impact on pilots’ workload depends on the design options, in particular the level of automation Generally, reduction in controllers’ workload


Considered as highly feasible in Paris area, possibly in London Gatwick, but unfeasible in London Heathrow and Frankfurt (due to complexity of current airspace) Potentially ATC efficiency benefits, through reduced R/T, establishing the sequence further out and more consistent spacing. More effective time-based spacing, but additional benefit over an ATC-based implementation not determined Different views on the level of automation required, and the actual need for ADS-B intent data Some concern over the consequence of controllers’ de-skilling and on the effect of system/sequence breakdown


For Paris and CDG in particular, there should be no blocking point for the use of ASPA-S&M London Heathrow characteristics seems hardly compatible with the use of S&M London Gatwick should allow the use of S&M Analysis suggests that S&M would be compatible with Frankfurt airspace characteristics

Table 10: Summary of results for the ASPA-S&M application

7.1.5. Apart from the ASPA-S&M applicability at Frankfurt, the operational feedback collected through the interviews and workshop and the applicability analysis performed within WP3 were consistent.



7.2. Final dissemination forum

7.2.1. The dissemination forum was held on the 8th July 2004 in the premises of Eurocontrol Head-Quarters in Brussels. Key elements of the FALBALA study were presented to European stakeholders and representatives of the operational community. It helped disseminating the results as widely as possible.

7.2.2. The forum agenda was two-fold: the morning session was dedicated to the results of the analysis of the current situation, i.e. work packages 1 and 2, and the afternoon session was dedicated to the results of the assessment of applicability, limitations and benefits performed within work packages 3 and 4.

7.2.3. The forum attendees (46) included representatives from various ANSPs (i.e. AENA, DGAC, ENAV, DFS, NATS), from the airlines (i.e. Air France), from the regulatory authorities (i.e. UK CAA), from the industry (i.e. Airbus, BAE System, Thales ATM), from the ATM R&D community (i.e. CENA, EEC, Helios, Ineco, NLR, QinetiQ, Sicta, Sofrévia, University of Glasgow), as well as representatives from various Eurocontrol entities (e.g., AGC and ADS programmes, Instillux, ATM and Surveillance domains).

7.2.4. The audience expressed its interest with regard to the amount of information provided during the forum. Some questions raised during the discussion sessions reflected expectations that were beyond the scope of FALBALA. Other questions gave the opportunity to explain the rationale behind some of the FALBALA results, typically those results that derived from subjective assessment by the authors (cf. Appendix A).

Analysis of the current situation

7.2.5. The synthetic and combined descriptions of ATM operations at major European airports was well received.

7.2.6. Some attendees asked for a better understanding of the interest of the analysis of the current situation within the scope of the study. It was also necessary to remind that the objective within FALBALA was not to determine the rationale for the current situation, but only to help understand it in support to the evaluation of possible operational benefits.

7.2.7. Other questions asked for the rationale of some conclusions of the analysis of the airborne traffic information characteristics, in particular those related to the probable safety benefits from the use of a CDTI. It was explained that these conclusions were drawn following the subjective analysis of traffic situations extracted from the radar data, based on the operational knowledge available within the project team.

7.2.8. At the end of the day, the need to assess the applicability and possible benefits of future ASAS operations in the context of various airspace characteristics was recognised.



Applicability, limitations and benefits assessment

7.2.9. The audience raised the issue that the opinions collected through the interviews and workshop were not providing evidence that the anticipated benefits would actually be achieved. It was also mentioned that the perception of increased safety does not necessarily mean that there is a need to increase safety.

7.2.10. Although it was agreed that the conclusions of the FALBALA study should not be taken as definitive, it was mentioned that the initial assessment performed during the study using various sources (including not only feedback from operational experts, but also real-time simulation outcomes) allowed getting some confidence in the results.

7.2.11. The potential capacity benefits expected from the ASAS applications were questioned. It was mentioned that there is a distinction between increase in capacity in nominal conditions (e.g. to cope with more traffic demand) and maintenance of current capacity under more frequent bases.

7.2.12. The link that exists between safety and capacity was also reiterated. With additional safety margins potentially brought about by the greater involvement of the pilots in ATM operations. It was noted that the investigated ASAS applications could also lead to an indirect increase in capacity.

7.2.13. The potential gain from more accurate desired aircraft spacing was asked for. It was explained that more regular traffic flows might result in less go-around and increased flight efficiency.

7.2.14. Finally, a set of issues raised during the forum, some of which had already been mentioned during the FALBALA operational workshop. These include:

• the impact of partial equipage on the expected benefits;

• the solution to partial awareness due to partial equipage; and

• the more appropriate level of automation.

7.2.15. It should be noted that it was outside the scope of FALBALA to determine how to achieve the potential benefits expected from the investigated ASAS applications.




7.3.1. During the first phase of the FALBALA study, the current traffic characteristics in core Europe have been assessed both from an overall airspace perspective, as well as from an airborne perspective.

• The WP1 analysis of the traffic patterns identified through the European radar data recordings provided a better understanding of the current situation within the Paris, London and Frankfurt TMAs.

• The WP2 analysis of the airborne traffic information characteristics simulated from the European radar data allowed an initial assessment of CDTI features, and airborne surveillance requirements, in support to airborne traffic situational awareness.

7.3.2. During the second phase of the FALBALA study, the objective radar data analysis performed within WP1 and WP2 was complemented by operational feedbacks collected within WP4, as well as the experiment result analysis performed in WP3.

7.3.3. An initial assessment of the operational applicability, benefits and limitations of three ASAS applications from Package I was performed using various sources of information, i.e. real-time simulation results (WP3), operational interviews and workshop (WP4).

7.3.4. The issues related to the extrapolation of operational benefits from experiments on generic environment to specific environment were identified. Although challenging, it is thought that the approach should be continued.

7.3.5. In conclusion, the FALBALA study has demonstrated that:

• the airspace and airport characteristics and the traffic demand should be considered when assessing operational applicability and benefits of AS applications envisaged for implementation.

• the radar data analysis is of particular interest to better understand the current situation and assess possible benefits within specific airspace and at various airports.

• operational benefits depend on the AS application and the operational environment.

7.3.6. For further information about the study results, access to the approved FALBALA deliverables is possible through the CARE-ASAS web site: http://www.eurocontrol.int/care/asas/careasas_activity_4.htm .



7.4. Recommendations for future work

7.4.1. Based on the experience gained within the FALBALA study, it is recommended to enhance the evaluation process based on radar data extrapolation in order to support to the benefit assessment in relationship with specific European environments.

7.4.2. Further in-depth analysis of the benefits identified for the ASPA-S&M and ASPA-AIRB applications should be performed, taking into account the potential limitations due to ASAS and CDTI design options. Such analysis could well be supported by a range of activities including:

• enhanced benefit evaluation based on radar data extrapolation. In particular, the safety benefits potentially brought by the ATSA-AIRB application and the increased ATM effectiveness expected from the ASPA-S&M application should be further analysed;

• development of experiments to support the test and validation of the ASPA-S&M application in various operational environments, including the use of arrival management tools;

• design studies, in particular for the appropriate traffic filter to support the ATSA-AIRB application as well as other ASAS applications, and the appropriate level of automation for the ASPA-S&M application;

• assessment of the level of aircraft ADS-B/ASAS equipage necessary to deliver benefit and the cost of avionics retrofit; and

• assessment of the most promising ASAS applications in comparison with alternative operational improvements identified within the Eurocontrol ATM 2000+ strategy.

7.4.3. With regard to the ATSA-VSA application, it is considered that an investigation of the differences in operations between United States and Europe, will support the assessment of the possible benefits.



8. References

[1] CARE-ASAS/Activity 5 ― Description of a first package of GS/AS applications ― CA02-040, version 2.2, September 2002

[2] CARE-ASAS/Activity 4 ― FALBALA Project Management Plan ― CARE/ASAS/SOF/03-055, version 1.1, September 2003

[3] CARE-ASAS/Activity 4 ― FALBALA Project ― WP1 Analysis of the current situation in the Paris, London and Frankfurt TMA ― CARE/ASAS/SOF/04-057, version 1.1, April 2004

[4] CARE-ASAS/Activity 4 ― FALBALA Project ― WP2 Analysis of the current situation from an aircraft perspective ― CARE/ASAS/CENA/04-058, version 1.1, June 2004

[5] CARE/ASAS Activity 4: FALBALA project ― WP3 Operational benefit report ― CARE/ASAS/EEC/04-059, To be delivered, June 2004

[6] CARE/ASAS Activity 4: FALBALA project ― WP4 Operational workshop and operational interview report ― CARE/ASAS/NATS/04-060, version 1.0, June 2004

[7] CoSpace ― Towards the use of spacing instructions for sequencing arrival flows ― Operational Datalink Panel (OPLINKP) Meeting of Working Group A, Annapolis, USA, November 2003

[8] EACAC 2001 Real-Time Experiment – Volumes I, II – Annexes, March 2003, I. Grimmaud, E. Hoffman, L. Rognin, K. Zeghal

[9] Initial Evaluation of CDTI/ADS-B for Commercial Carriers: CAA’s Ohio Valley Opertianal Evaluation ― Vernol Battiste and Rose Ashford, NASA Ames Center, Baltazar Oscar Olmos, MITRE Center for Advanced Aviation Systems Development ― Society of Automotive Engineers, Inc, 2000



9. Acronyms AIP Aeronautical Information Publication ANS Air Navigation Services ANSP Air Navigation Services Provider AS Airborne Surveillance ASAS Airborne Separation Assistance System ASPA Airborne Spacing ASPA-S&M Enhanced Sequencing and Merging operations ATC Air Traffic Control ATM Air Traffic Management ATSA Airborne Traffic Situational Awareness ATSA-AIRB Enhanced Traffic Situational Awareness during flight operations ATSA-SVA Enhanced Successive Visual Approaches ATSA-VSA Enhanced Visual Separation on Approach CAA Civil Aviation Authority CARE Co-operative Actions of R&D in EUROCONTROL CENA Centre d’Etudes de la Navigation Aérienne CDG Charles de Gaulle CDTI Cockpit Display of Traffic Information DFS Deutsche Flugsicherung GmbH EEC EUROCONTROL Experimental Centre FALBALA First Assessment of the operational Limitations, Benefits & Applicability for a

List of package I AS applications GA General Aviation IAF Initial Approach Fix IFR Instrument Flight Rules ILS Instrument Landing System INI Initial (approach) METAR Meteorological Aerodrome Report NATS National Air Traffic Services ND Navigation display RNAV Area Navigation RVA Radar Vectoring Area STAR Standard Arrival Route SOFREAVIA Société Française d’Etudes et Réalisations d’Equipements Aéronautiques TMA Terminal control Area UK United Kingdom UoG University of Glasgow US United States VFR Visual Flight Rules WP Work Package



Appendix A: Main issues discussed at the FALBALA dissemination forum

A.1. General

This appendix provides an overview of the main issues discussed at the FALBALA dissemination forum that dealt with the benefit assessment of the three studied ASAS applications:

• Enhanced Traffic Situational Awareness during flight operations,

• Enhanced Visual Separation on Approach, and

• Enhanced Sequencing and Merging operations.

It reports on the main questions from the audience, as well as the answers and comments from the FALBALA project participants.

A.2. Enhanced Traffic Situational Awareness during flight operations

Are the human factors aspects linked to too much head-down time taken into account when anticipating safety benefits for VFR flights?

Answer: Out of the scope of FALBALA. Opinions expressed in WP2 study are based on operational knowledge of the authors (some being VFR pilots and PPL flight instructors).

Are airborne surveillance performances already defined?

9.1.2. Answer: No standard performances yet defined, although safety and performance requirements are being investigated in various arenas (e.g. RFG, AGATA). The FALBALA contribution was only related to one parameter, i.e. the maximum number of targets in core Europe.

Which solution to partial awareness? Is TIS-B required to fill the gap?

Answer: The issue of partial awareness depends on the AS application. It was out of the scope of FALBALA to assess the solutions to the issues identified.

A.1. Enhanced Visual Separation on Approach

It is suggested that ATSA-VSA can extend the use of VSA in deteriorating weather conditions. DFS statistical analysis at FRA (Frankfurt) shows that pilots and ATC continue to operate in VSA procedures and deliver the same capacity, so implying Enhanced-VSA wouldn’t add much.

Answer: Noted.



Does expectation for safety benefits mean that the current system is not safe?

Answer: An increase in the safety buffer can be expected even if there is no indication that the current operations are beyond the limits and that such additional safety margins are required.

A.2. Enhanced Sequencing and Merging operations

Did experts consider the workload effect in establishing the sequence (or VSA), or just the consequential workload effect from R/T reduction?

Answer: The detail of how a controller would indicate an aircraft to a pilot and how the pilot would acquire the target aircraft was not specifically questioned, only the consequential reduction in R/T due to establishing the sequence earlier and the reduced need for tactical instructions once established. It is a valid question, although it should be noted that some of the operational experts had experience of the CoSpace S&M experiment as well as London and Paris current operations, and so would have been familiar with all aspects of the application. They did not raise this point as an issue.

Surely within the TMA and within the scope of ASAS Package 1, ATC instructions will still be by R/T, and not CPDLC, due to time criticality. Therefore there will be no loss of party line, and therefore ATSA-AIRB will not need to supplement the party line. Answer: True in part, but some of the identified benefits of the application include establishing the traffic sequence further out and reducing the time-criticality of instructions. Instructions could then be conceivably be passed by data-link and not voice. Also, ATSA-AIRB would be used in en-route airspace as well, which will be a data-link environment, due to Link2k+.

About levels of automation required: DFS suggested a level of cockpit automation would be necessary because, in the FRA (Frankfurt) case, a heavy aircraft cannot follow the same turning track as a light aircraft and this is a problem in flying 180 degrees in their trombone-like approach path.

Answer: As the WP4 concluded, it is still debateable whether such capability is essential for Package 1. This does raise the specific issue of (and limitation caused by) the tight semi-circular track flown at FRA and the consequence to any implementation of ASPA-S&M.

4D Trajectory Control versus ASPA S&M: Does one give benefit over the other, and if so which?

Answer: Outside the scope of FALBALA to assess this. It was raised as a question to be addressed and is included in the conclusions.



What is the impact of partial equipage on the S&M applicability and benefits?

Answer: It depends what is meant by partial equipage (i.e. ADS-B out or ASAS guidance). The actual impact on the operational use of the application if not all aircraft are capable to do it is still to be investigated.

What are the actual benefits expected from more accurate desired spacing?

Answer: These include less go-around, increased flight efficiency. How this translate into increased capacity is still an open question.

There is a need to distinguish between increase in capacity, and maintenance of the capacity during longer periods.

*** END OF DOCUMENT ***

Documents

FALBALA – Final Project Report - Eurocontrol | - Driving ... Final Project Report 15-07-2004 FALBALA/WP5/FPR/D Version 1.0 EUROCONTROL CARE/ASAS/Sofréavia/04-061 – FALBALA Project