45TH ANNUAL CONFERENCE, Kaohsiung, Taiwan, 27-31 March 2006
WP No. 105
ASAS-TN2 – Airborne Separation Assistance System Thematic Network 2
Presented by Anthony Smoker, IFATCA Representative to ASAS-TN2
1.1 The ASAS (Airborne Separation Assistance System) Thematic Network is a European Commission project, which brings together the stakeholders engaged in ASAS R+D, to hasten implementation.
1.2 The Thematic Network draws from the global ASAS community thus there are a wide range of operational contexts and ASAS design solutions that are brought together.
ASAS is about the pilot doing ATC isn’t it?
2.1 Well actually, it is not, and ASAS will soon be providing operational benefits to ATCOs in their daily task – indeed, in pre-operational trials they do so already on a daily basis.
2.2 ASAS is organised into three packages – Package I, II and III. These equate to near term, mid term and long-term applications. Alternatively, one can consider these as maturity steps towards some end state. The precise end state is still being developed, but it embraces the concept of self-separation by the flight deck. This is a gross simplification however.
2.3 ASAS Package 1 now consists of 10 ASAS applications (two having been merged with others) grouped into three classes:
- Ground Surveillance applications: ADS-B-GS
- Air Traffic Situational Awareness Applications: ADS-B-ATSA
- Airborne Spacing and Passing Applications: ADS-B-ASPA
2.4 These sub-divide into the ten applications in Appendix One provides the definitions that the ASAS community agreed, and work with.
What is ASAS-TN?
3.1 The ASAS-TN is a Thematic Network that was established specifically to address the observation among European organisations that there was little co-ordination between ASAS projects across Europe. This has led to redundant work and to topics not being addressed or being treated in sufficient depth. It was also identified that research within Europe was not harmonised with US research activities and that global standardisation could not begin until this was achieved. The output of a Thematic Network consists of seminar and workshop reports and a final report that considers the progress of the specific subject being studied.
3.2 The Thematic Network draws from the global ASAS community thus there are a wide range of operational contexts and ASAS design solutions that are brought together.
3.3 The ASAS-TN:
- Facilitates the exchange of ideas to provide a framework for discussion and to ease the dissemination of information;
- Provides a data base of ASAS related documents to support studies and projects;
- Facilitates the training of people involved in the development process of ASAS applications;
- Facilitates co-ordination of on-going Research and Technical Development (RTD) projects related to ASAS and specifically between ground and airborne oriented projects;
- Facilitates consensus for standardisation and certification;
- Provides guidance and recommendations for future ASAS strategy including RTD, technical feasibility, validation and implementation; and
- Allows the presentation of results and discussion of information with stakeholders.
3.3 The most recent workshop (Malmo, September 26-28th 2005 is the first of five in ASAS-TN 2. ASAS-TN1 concluded in Brighton one year ago, so this recent workshop sets the scene for the next iteration.
3.4 The ASAS-TN is managed by a consortium led by EUROCONTROL that includes BAE Systems, ENAV, LFV, NLR, THALES ATM and THALES Avionics. In addition to the above organisations, the ASAS-TN involves a very wide range of organisations (e.g. ATM stakeholders, Universities) including pilot and controller professional associations (ATCEUC, IFATCA, IFALPA and ECA).
3.5 ASAS-TN work programmes take two forms, workshops and a document that reviews and comments on the work carried out in the focus area.
4.1 ASAS-TN 1 existed for two years, from January 2003 until December 2004. Three workshops and a seminar were held. The output of the thematic network will be found in the ASAS-TN Work Package 3 documents “ASAS Implementation Strategy” (ASAS-Implementation Strategy. ASAS-Thematic Network, (2004) Eurocontrol Experimental Centre. Bretigny). Additionally, workshop and seminar reports were produced.
4.2 The workshops are tabled below:
4.3 For each of the workshops and seminar, a report is published. These can be found on the ASSA-TN website at the following address: https://asas-tn.eurocontrol.fr/tn1/workshops.html
Results of ASAS-TN 1
5.1 The output of the thematic network can be found in the ASAS-TN Work Package 3 document “ASAS Implementation Strategy”. The conclusions from the work of the thematic network are presented in Appendix two.
5.2 Work Package 3 made a number of recommendations with the intention to speed up the progress of implementation of ASAS. These can be found in Appendix three.
5.3 In brief, there was considerable frustration that despite the extensive research activities that have been carried out, in Europe at least, there was little progress towards implementation of an operational system.
5.4 Elsewhere in the world however, ASAS applications are being deployed, notably Australia, in the Burnett Basin, and the establishment of ADS-B surveillance above FL290 across the UIR. In the USA, the CAPSTONE project uses ADS-B for ATSA applications, and after the Ohio River trials, certain Cargo Airline Association operations use ADS-B and a Cockpit Display of Traffic Information for other ASAS applications. The majority of these ASAS applications, but by no means all, are of the nature of surveillance only, and in some cases do offer safety benefits.
5.5 It was evident from the workshops that although the technology of ASAS is maturing, that there is still a naïve idea of how it will be applied. In part, this is because the lure of “self-Separation” ASAS applications is so great – it is very seductive. In practise, these applications are along way away. Indeed, many of the strongest ASAS supporters do not fully understand just what will be required to implement certain ASAS applications that involve the flight deck. Certification of ASAS applications that involve the flight deck will be complex and costly. Training flight crew and controllers will also be costly and time consuming. Without these in place, few of the ASAS applications of the ATSA or ASPA classes can be deployed.
6.1 ASAS-TN2 will last three years, and has been established with the following objectives:
- The main objective of the ASAS Thematic Network 2 is to accelerate the implementation of ASAS applications in European Airspace, taking into account global applicability in order to increase airspace capacity and safety.
- The transfer and comparison of information and results on ASAS research will meet the main project objective in order to improve the research strategy.
6.2 The work programme will include five workshops and one summary seminar. The subjects of each of the workshops will develop particular themes related to implementation issues. Whereas ASAS-TN1 was limited to ASAS Package I applications, Package two will include Package II and III i.e. separation transfer.
6.3 Work Package 3 of the ASAS-TN2 programme aims to develop a yearly maturity assessment related to ASAS applications. The review the progress of research and development, operational standards (e.g. ICAO SARPs), technical standards (e.g. MASPS and MOPS from RTCA/EUROCAE) and implementation. The approach taken is to cluster the ASAS applications and develop a template to identify the maturity and severity of specific dimensions of the implementation cycle. The model used to develop this approach is a formal and recognised technique in system engineering.
6.4 The Application Clusters for the maturity assessment, and the reviewers within the consortium are:
- ADS-B Surveillance: Thales ATM
- Situation Awareness: Thales Avionics
- Runway applications: LFV
- Spacing: ENAV
- Separation: BAE Systems
- Self-Separation: NLR
6.5 The first ASAS-TN2 workshop was held in Malmo, Sweden between September 26th and 28th 2005. It was entitled “Implementing ASAS”, and was largely a review of ASAS implementation to date. The report is published, and can be found at: https://asas-tn.eurocontrol.fr/reports.html.
6.6 This workshop provided some reassurance that the human and operational issues were seriously considered by those present and in the ASAS community. However, there remain several mis-conceptions, on just what is achievable or even desirable in ASAS operations. There were numerous observations pertinent to IFATCA, and these can be found in the other reports presented.
6.7 The second ASAS-TN2 workshop will be held in Rome in April 2006, and is entitled “ASAS as an integral part of future ATM”. IFATCA will present a paper at this workshop.
7.1 ASAS systems have been a long time coming, and the potential for disparate approaches that would lead to a lack of inter-operability and duplication of effort has been recognised. ASAS-TN2 is a vehicle accepted as significant in bringing the global ASAS stakeholders together.
7.2 The ASAS partners have welcomed IFATCA into the ASAS-TN management group, and a very good working relationship has been established, where the importance of the controller perspective is respected and recognised as a significant contribution to the development and implementation of ASAS applications
8.1 That this paper be accepted as information material.
Appendix 1 – ASAS Application Clusters
ATC surveillance for en-route airspace and in in terminal areas (ADS-B-RAD):
ADS-B is going to enhance ATC surveillance currently provided with radars. This is particularly the case at low altitude and close to the terrain and also in areas where, for example, single radar coverage is provided.
ATC surveillance in non-radar areas (ADS-B-NRA):
ADS-B is going to provide ATC surveillance in non- radar areas; e.g. remote areas, offshore operation areas, any continental areas and certain oceanic areas, which, due to the level of traffic or the cost of the equipment, could not justify the installation of radars. The purpose is to enhance traffic information and separation services.
Airport surface surveillance (ADS-B-APT):
ADS-B is going to provide a new source of surveillance information for SMGCS and possibly to contribute to runway incursion alerting. This is particularly the case for large airports already equipped with an SMGCS. For smaller airports, this application will allow the implementation of basic airport surveillance. Airport ground vehicles can also be fitted with the necessary equipment and displayed on an airport map, together with aircraft.
Aircraft derived data for ATC tools (ADS-B-ADD):
The objective of the application is to provide additional aircraft derived data through ADS-B to be used by the ATC ground system for developing or enhancing ATC tools like displays, MTCD, AMAN, DMAN and ground based safety nets.
It should be noted that this application does not encompass the ATC tools themselves; it only provides additional input data for these tools.
Enhanced traffic situational awareness on the airport surface (ATSA-SURF):
This application provides the flight crews with an “enhanced traffic situational awareness” on the airport surface for both taxi and runway operations, in all weather conditions. The objectives are to improve safety (e.g. at taxiway crossings, before entering a runway, on pushback) and to reduce taxi time in particular during low visibility conditions or at night.
Enhanced traffic situational awareness during flight operations and visual acquisition for “see & avoid” (ATSA-AIRB):
This application provides the flight crews with an “enhanced traffic situational awareness” during flight operations in all weather conditions. Additional data is provided to flight crews to supplement traffic information provided either by controllers or by other flight crews. The objectives are to improve safety of flight and the efficiency of air traffic control. In procedural-controlled airspace, the flight crews will be able to detect unsafe situation. In radar-controlled airspace, the flight crews will better understand the reasons of ATC instructions.
This application is an aid for the flight crews to perform their collision avoidance task when separation service in not provided by ATC (e.g. IFR/VFR in class D and E airspace, class G airspace). The objective is safer flight operations.
Enhanced successive visual approaches (ATSA-VSA):
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.
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.
In-trail procedure in oceanic airspace (ASPA-ITP):
The In-Trail Procedure in non-radar oceanic airspace is a procedure allowing in-trail ADS-B equipped aircraft, which may not be longitudinally separated from each other, to climb or descend through each other’s flight levels. The objective is to improve the utilisation of the NAT oceanic airspace by facilitating a higher rate of flight level changes than is currently provided, yielding better flight efficiency (e.g. fuel savings, avoiding turbulent flight levels).
Enhanced crossing and passing operations (ASPA-C&P):
The objective is to provide the controller with a new set of instructions to solve conflicts directing, for example, the flight crews to cross or pass a designated traffic while maintaining a given spacing value. The flight crews will perform these new tasks using a suitable human-machine interface. The main expected benefit is increased controller availability through the reorganisation and the streamlining of tasks.
Appendix 2 – Conclusions of the ASAS-Thematic Network One
(Taken from the ASAS-TN ASAS-Implementation Strategy. ASAS-Thematic Network, (November 2004))
In order to speed up the introduction of ASAS and ADS-B, a package of applications that could be implemented within a 5 to 10 year period has been defined. This timeframe is a challenge but experts consider it feasible. It is possible to go faster with a local implementation of specific applications but ‘Package 1’ defines a set of operational applications offering benefits for a large majority of airspace users.
The packaging approach is pragmatic and aims at the early implementation of these applications on a worldwide basis. ‘Package 1’ is going to help to focus the energies required for the development of the appropriate operational/technical standards and equipment. The approach is flexible. States, ANSPs and airspace users may select, from the set of applications, those that are the best suited to their operations and their needs and then opt for actual implementation. However, ‘Package 1’ applications were meant to be taken as a whole in terms of standards and equipment.
The basic strategy is to begin implementation of ASAS and ADS-B concepts at a local level so that the proof of concept and associated benefits can be demonstrated operationally at low cost to the airlines and ANSPs. Once the benefits have been demonstrated operationally, the aircraft operators can be encouraged to equip all of their aircraft and enable the application of ASAS and ADS-B concepts to become more widespread. The first part of this strategy requires that sufficient aircraft operating within a single airspace are equipped so that they become ASAS/ADS-B capable. This will require the introduction of ASAS functions into the cockpit. These functions will improve situation awareness in the cockpit by providing a CDTI capability and will enable ASAS manoeuvres to be implemented by providing appropriate guidance information to the pilot.
The introduction of ASAS and ADS-B presents a number of challenges including the generation of a clear operational definition, technology issues and certification of new equipment. It is clear that for ASAS to progress there has to be support from aircraft operators, pilots, ANSPs, controllers and equipment manufacturers. In order to achieve this, the roles and responsibilities of both the pilot and controller for each application must be clearly defined so that safety is not compromised. There is a cost associated with the introduction of ASAS and ADS-B, much of which will be paid by airlines and ANSPs. Therefore, the benefits to the airlines and ANSPs of implementing ASAS and ADS-B must be sufficient to justify the investment costs. The use of incentives or, where appropriate mandates, as a way to accelerate deployment should also be considered as a means of transferring costs to the party that benefits.
ASAS and ADS-B are not purely European issues but global ones. It is important for global activities to be co-ordinated so that GS/AS applications and terminology become standardised. Across Europe and the US, GS/AS applications have been developed and demonstrated within many research programmes. The Requirements Focus Group (RFG) provides a framework for co-operative work between the USA, Europe and now, Australia and Japan. It will ensure that the experience gained from the various research programmes is reflected in ASAS/ADS-B standards.
For the long-term, work needs to continue on applications for ‘Package 2’ and ‘Package 3’. This requires more analysis of the safety implications of delegating responsibility for separation applications, including self-separation, to the cockpit.
The selection of the ADS-B datalink technology has proved to be a stumbling block and implementation of ADS-B has been slowed down by the lack of agreement. This position has been changing. At ANConf/11, it was noted that one of the key factors in selecting a datalink technology appeared to have been a requirement to ensure global interoperability while enabling the near-term introduction of ADS- B services. The main consequence of this is that most early implementations are likely to be based on SSR Mode S extended squitter although some regions may adopt alternative approaches. It is also expected that additional alternative link technologies will be required in the future in order to meet requirements for integrity and capacity. In Europe, the initial deployment of ADS-B will be based on SSR Mode S extended squitter with VDL Mode 4 providing regional implementations and a dual link capability where necessary.
Among the various applications identified for inclusion in ‘Package 1’, there is a subset that is expected to bring early benefits. The benefits arise because many aircraft are being equipped with SSR Mode S extended squitter and as result, are visible to any suitably equipped receiver.
In areas with no existing radar cover or restricted radar coverage, the introduction of ADS-B-out equipped aircraft will enable ANSPs to provide a radar-like service. The Upper Airspace Project in Australia is leading the way here by installing a large number of ADS-B ground stations. This is expected to provide a significant improvement to the service supplied to the aircraft operators while reducing the long-term cost to the ANSP.
Another GS application that would be suitable for early implementation is ADS-B-APT. This is of immediate benefit to airports that are not equipped with SMGCS and where restricted visibility as a result of poor weather is a frequent occurrence. At airports equipped with SMGCS but with restricted ground surveillance cover or blind spots, the application is expected to provide benefits by providing an additional source of position information. A related application is ATSA-SURF. This could enhance situation awareness in the cockpit while the aircraft is on the airport surface. The full benefits of this application though, will only be achieved when all aircraft and relevant ground vehicles are ADS-B-out equipped. During the transition period, the benefits would only be achieved if the positions of non-equipped aircraft and ground vehicles were made available to equipped aircraft.
The AS application expected to generate the greatest benefit in the short term is the ASPA-S&M application. This provides a means for controllers to create more regular flows of aircraft. The new instructions should decrease the controller workload, without significantly changing the pilot workload, by reducing the need for tactical control of aircraft within a sector. The main expected benefits are reduced controller workload and potentially, increased capacity through better adherence to the optimum approach spacing.
Progress towards the implementation of ASAS in Europe has been slow but steps are being taken to speed this up. The North European Update Programme (NUP) and the Mediterranean Free Flight (MFF) project are progressing. The first stages of planning for large-scale evaluation trials began in January 2004 with the start of the European Union part Trans European Network (TEN) project called SEAP.
ASAS-TN has provided the means to share the current knowledge on ASAS/ADS-B between all European stakeholders and provides recommendations for future activities required to reach the operational use of GS/AS applications. It is expected that these results will be of use to guide European actions. The expectation is also that the shared knowledge and the agreed recommendations will allow European industry to optimally plan and focus their new product development strategy.
Appendix 3 – ASAS-TN One Recommendations
Recommendations for an Early Implementation Strategy
ASAS and ADS-B are not purely European issues but global ones. It is important for global activities to be co-ordinated so that GS/AS applications and terminology become standardised. The Requirements Focus Group (RFG) has been created to co-ordinate ASAS activities between Europe and the US.
Recommendation 1: It is essential that the RFG continues to bring together the experience and knowledge from global ASAS and ADS-B activities in order to define a common set of GS/AS applications along with the associated safety and interoperability requirements.
In order to support the work of the RFG, the results from European research projects such as MFF, NUP and MA-AFAS need to be validated with respect to safety, human factors and pilot acceptance.
Recommendation 2: The ASAS and ADS-B validation work should be accelerated and co-ordinated within Europe across the NUP, SEAP, C- ATM, LAVA and other programmes.
There have been many studies on the ADS-B datalink technology and the evidence from the studies has been less than conclusive. The main conclusion from the studies is that most early implementations are likely to be based on SSR Mode S extended squitter although some regions may adopt alternative approaches. It is also expected that additional alternative link technologies will be required in the future in order to meet requirements for integrity and capacity.
Recommendation 3: In line with ANConf/11 recommendations 7/1 and 7/2, the initial deployment of ADS-B in Europe should be based on SSR Mode S extended squitter with VDL Mode 4 providing regional implementations.
In order to provide incentives for aircraft operators to equip aircraft, it is important to demonstrate the operational performance and cost benefits to the aircraft operators early. This can probably best be achieved by initially targeting local areas where it is feasible to equip sufficient numbers of aircraft to enable the benefits of ASAS and ADS- B to be demonstrated.
Recommendation 4: Demonstrate ASAS and ADS-B benefits at local level first.
The initial implementation should be capable of handling many of the ‘Package 1’ applications and of being extended to handle some ‘Package 2’ type applications. The implementation could be largely independent of other aircraft systems and as a consequence would probably include its own display and control units. In such an implementation, the pilot will control the aircraft during spacing manoeuvres using the autopilot.
Recommendation 5: Develop a retrofit solution for equipping existing aircraft.
This approach to a retrofit solution should enable earlier introduction of ASAS and ADS- B because it reduces the extent of aircraft modification and hence certification required. The main limitation with this approach is that it is a short term solution. It may not provide the operational flexibility or automated operation required for the long-term.
Recommendation 6: The preferred implementation in the long-term of ASAS and ADS-B applications is expected to be within a fully integrated, dual redundant avionics system.
The integration of ACAS display information with the ADS-B display information needs to be considered for the initial implementation and particularly for the final implementation where a common display surface is likely to be used.
Recommendation 7: It is essential that the ADS-B based traffic display and ACAS display do not present conflicting pictures and that the presence of ADS-B information does not in any way compromise the safety net provided by ACAS.
Among the various applications identified for inclusion in ‘Package 1’, there are three applications that are expected to bring early benefits in Europe:
In areas with no existing radar cover or restricted radar coverage, the introduction of ADS-B-out equipped aircraft will enable ANSPs to provide a radar-like service.
Recommendation 8: Consider the ADS-B-NRA application for early implementation.
The other GS application that would be suitable for early implementation is ADS-B-APT. This is expected to provide benefits at airports with restricted ground surveillance cover or where there is no existing surveillance system and restricted visibility as a result of poor weather is a frequent occurrence.
Recommendation 9: Consider the ADS-B-APT application for early implementation.
Last Update: September 29, 2020