1. Air-Ground Data Link - DFS Strategy
ATN’99 - An International Conference on the Implementation of Aeronautical Datalink
23 September 1999
Speaker: Thomas Belitz, DFS Telecommunications
In early 1997 DFS has addressed the question, if the provision of future Air Traffic Services should also include elements of Air-Ground datalink communication. Furthermore, the drafting of a realistic implementation scenario was desired. In order to give a consolidated answer to that question, a working group of multidisciplinary DFS-experts was formed. The task was to identify
current shortcomings of the ATS-environment and their possible relief enabled by Data Link,
operational requirements for Data Link enabled services,
the impact on operational systems in use and those planned for the future.
Taking into account the answers to these questions, an implementation scenario for DFS-provided Data Link enabled Air Traffic Services was created. Furthermore the group attempted to analyse the company-wide ratio of cost-benefit.
Finally the overall work of the expert group was formed to a draft DFS strategy on Air-Ground Data Link. This material was endorsed by DFS’ senior management in October 98.
This presentation is focused on the bottom line of the mentioned DFS Data Link Strategy. This strategy is still valid, although the international environment of aviation has further developed and DFS is a part of it.
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2. Air-Ground Data Link - DFS Strategy Contents
1. Today‘s Shortcomings
2. Environment
3. Operational Requirements
4. Air-Ground Data Link Media
5. DFS-ATM-Systems/ Processes
6. Implementation Scenario Phase 1 (from 2005)
7. Implementation Scenario Phase 2 (from 2007)
8. Benefits according to Implementation Phases
9. Cost-Benefit Considerations
10. Summary
11. Conclusions

3. Today‘s Shortcomings increasing number of aircraft results in
reaching capacity limits on voice frequencies/ frequency shortage
overload of executive controllers
increasing challenge to ensure the safety of flight
voice communication implies potential of misunderstandings
no automated exchange of information between data processing systems in the Air and on the Ground
Traffic growth in Europe/ Germany
especially in the airport environment voice frequencies are often overloaded; e.g. flight crews have to wait for their “voice communication slot” e.g. in order to get a Departure Clearance
very high workload for many controllers, sectors can not be splitted further
the increasing number of aircraft implies a significant increase in the potential for separation conflicts
In the voice communication environment, the Human operator (Pilot/ Controller) is the only interface for in-flight ATS-information exchange between highly sophisticated data processing systems on board and on the ground.
Airlines are increasingly requesting Data Link clearances, e.g. Departure Clearance (DCL) in order to overcome voice congestion.
Airline requirements regarding data link are not satisfied

4. Environment Relevant Strategies and Programs
ATM 2000+
The strategy was elaborated by a EUROCONTROL chaired Strategy Board in order to meet a request by the ECAC Transport Ministers for a comprehensive gate-to-gate oriented ATM Strategy for the year The board represents all parties involved in European Aviation (ATSOs, Airlines, Airports, Industry, etc.).
ATM foresees a phased implementation (2005, 2010) and an intensive use of Date Link as an enabler for operational benefits.
EATMS-OCD
European ATM System - Operational Concept Document The document describes the operational Concept of the future European ATM system. Data Link - Services are essential for the realisation of the expected operational benefits
EATCHIP-Communications Strategy
The document describes the future European ATM communication infrastructure. Air-Ground Data Link is a significant element of this strategy.
FAA NEXCOM Program
Phase 1 - CPDLC Build I (Implementation )
FAA develops first ICAO-ATN-SARPS-compliant Data Link Applications, 4 Messages are foreseen (Transfer of Communication, Initial Contact, Altimeter Setting, Pre- Defined Messages)
Implementation planned for the Miami- Centre
VDL M2 is the selected Air-Ground Data Link Medium (provided by ARINC)
Phase 2 - CPDLC Build IA (Implementation )
Extension to 18 messages planned (e.g. Pilot Initiated Downlink), special consideration of the EUROCONTROL-PETALII results
Implementation at additional sites
Phase 3 - CPDLC Build 2 (Implementation )
enhanced message set of more than 100 messages, Interoperability with the PETALII- message set
Implementation at all FAA sites
Phase 4 - CPDLC Build 3, NEXCOM ( ) - Next-Generation Air/Ground Communications
Segment 1 ( ); Procurement and Installation of Multimode Radios (VDL M3 capable Radios, used initially only for analog voice or digital voice in upper airspace)
Segment 2 ( ); Integration of Data Link Services (VDL M3)
Segment 3 ( ); Implementation of VDL M3 in selected TMAs and selected sectors in the lower airspace
LINK 2000+
under the umbrella of EUROCONTROL, representatives from airlines, air navigation service providers and other organisations are currently in the process to define a programme to implement an initial set of Data Link services in Europe.
There is an active participation of DFS in the ongoing LINK2000+ activities (drafting group/ CBA).
PIT - PETAL Integration Team
PETAL - Preliminary Eurocontrol Test of Air/Ground Data Link
Operational Trials with international participation: (EUROCONTROL, ATSOs, AAL, ARINC, FAA, Research organisations, others)
Focus is on validation of operational benefits from ATS- data communications
Message set is based on ODIAC- definitions
the current implementation is a sub-set of the ICAO-ATN-SARPs. Air-Ground Media are VDL M2 and others
timeframe
Military Aviation
Presently there is no specific Requirement for ATS-Data Link Services
Environment Relevant Strategies and Programs
Strategies, approved by DFS
ATM 2000+
EATMS-OCD
EATCHIP-Communications Strategy
Important Programs
FAA- NEXCOM- Program
LINK 2000+
PIT - PETAL Integration Team
Military Aviation
There was no specific military requirement for ATS-Data Link Services identified yet.

5. Environment EATCHIP Communications Strategy (dated July ´98) Mobile Network Services Deployment
BACKUP
Source:
EATCHIP Communications Strategy - Volume 2 - Technical Description (July 98)
BACKUP

6. Environment EATCHIP Communications Strategy (dated July ´98)
BACKUP
Source:
EATCHIP Communications Strategy - Volume 2 - Technical Description (July 98)
greyed activities are relevant to Data Link
BACKUP

7. Operational Requirements Data Link Services - specific to DFS
D-ATIS (INDAL)
D-FIS
D-OTIS, D-RVR, D-SIGMET
D-DCL (INDAL)
CPDLC
DCL, CIC, ACM, (COTRAC)
CAP, SAP
ADAP
PPD, (ADS)
The chart refers to the Data Link services requested by the DFS operational services. The chart does not take into account the real situation of DFS technical infrastructure and migration feasibility. Thus it serves as a contour towards a DFS-migration path.
D-ATIS (currently covered by the DFS-project „Initial Data Link -INDAL“)will be replaced/ supplemented by D-OTIS. The INDAL service „D-DCL“ will be continued according to the ODIAC- Definition.
COTRAC = Common Trajectory Co-ordination; COTRAC is a new service, currently under development by ODIAC.
FLIPCY
others
others
year
CPDLC Controller Pilot Data Link Communication
CIC Clearance and Information Communication
ADAP Automatic Downlink of Aircraft Parameter
ADS Automatic Dependant Surveillance
DAP Downlink of Aircraft Parameter
CAP Controller Access Parameters
PPD Pilot Preference Downlink
SAP System Access Parameters
FLIPCY Flight Plan Consistency
D-FIS Data Link Flight Information Service
D-OTIS Data Link Operational Terminal Information Service
D-RVR Data Link Runway Visual Range

8. Air-Ground Data Link Media Assumption of Availabilities
Alternative Media
The assumptions on data link media availability is a reflection of knowledge, gathered by DFS-experts who participate in several international working groups (e.g. AMCP-Aeronautical Mobile Communications Panel).
ACARS will be replaced by VDL M2 in the medium to long term. This process is estimated to last at least one decade.
Due to adjacent channel interference problems, the VDL M2 SARPs have been reworked. Resulting from this, certified equipment will not be available before late 2001.
The selection of suitable VOCODERS for VDL M3 has been done recently. Equipment certification work can be started after ICAO-SARPs adjustments that will follow the VOCODER selection.
The validation work of the VDL M4 ICAO-SARPs has started in spring 1998, its finalisation is expected for fall 1999.
It can be considered that only one technology - VDL M3 or M4 - will be implemented in one airspace finally.
The usage of SSR Mode S as a means of communications is based on it‘s earlier deployment in the context of „Enhanced Surveillance“.
SATCOM refers only to the present-day geo-stationary INMARSAT- system. Reliable facts concerning new emerging LEO- and MEO- systems were not available in time. This area has to be investigated in more detail.

9. DFS-ATM-Systems/Processes Potential in Performance-Enhancements resulting from the introduction of Data Link Services
The table lists DFS-systems/ processes that may profit from the introduction of data link services.

10. Implementation Scenario Phase 1 (from 2005) Non-Time Critical Services
Alternative Media (Selection of complementary media by 2001)
INDAL (D-ATIS, D-DCL)
CPDLC (DCL, CIC- none time critical)
ADAP (CAP, SAP)
DFIS (D-OTIS, D-SIGMET)
FLIPCY
DL-Services
A/G-Mediea
ACARS
VDL M2 primary datalink
Mode S Com
SATCOM, complementary datalink
The chart shows the introduction of non-time critical data link services in conjunction with the availability of media and the necessary stage of compatibility of relevant ATM-systems.
From about 2001 onwards, VDL M2 will de facto be introduced by the Airlines as ACARS-successor, mainly driven by AOC- requirements. This situation establishes good conditions, to make ATS-Data Link services available to many airspace users.
In an early phase the DFS-project „INDAL“ will offer initial data link services to the airline customers using the present ACARS-system. These services will later be offered to the airspace users via VDL M2 (D-OTIS, DCL, „learning phase“ for VDL M2). Further non-time critical applications will be implemented gradually.
It will become necessary to assess the need for a complementary data link and to decide about its selection and implementation at a later point in time.
The preparation of relevant ATM-systems and ground networks for the processing and transport of data associated with the air-ground link is substantial.
ATM-Systems
System adaptations
year

11. Implementation Scenario Phase 2 (from 2007) Time Critical Services
CPDLC(CIC-time critical), ADAP(PPD, ADS), DFIS(D-RVR), others
DL-Services
Alternative Media (Selection by 2001)
ACARS
VDL M2 primary link (non-time critical services only)
Mode S Com, complementary link
A/G-Link Media
SATCOM, complementary link
Alternative Media (Selection by 2002)
VDL M4
VDL M3
In connection with the implementation of a highly reliable data link media (VDL M3 or VDL M4), time critical services will be introduced from 2007 onwards.
With the increasing degradation of ACARS, the ACARS-carried services will be transferred to VDL M2.
VDL M2 will become the primary link for non-time critical data link services.
In the case that a complementary data link will become necessary, Mode S and SATCOM are candidates (or outsiders like LEO/MEO).
ATM-system adaptations become necessary with the introduction of every additional service (e.g. HMI).
System adaptations
ATM-Systems
year

12. Benefits according to implementation phases
The effects shown in the table have to be understood in an accumulative manner. This means Phase 1 shows the growth of benefit compared to the benefit generated by phase 0 and so on.
The assessment shown are based on operational considerations. It therefore points at fields that are most promising for the realisation of user benefits.
„Quality of Service“ has to be interpreted from the customers point of view.
CPDLC Controller Pilot Data Link Communication
CIC Clearance and Information Communication
ADAP Automatic Downlink of Aircraft Parameter
ADS Automatic Dependant Surveillance
DAP Downlink of Aircraft Parameter
CAP Controller Access Parameters
PPD Pilot Preference Downlink
SAP System Access Parameters
FLIPCY Flight Plan Consistency
D-FIS Data Link Flight Information Service
D-OTIS Data Link Operational Terminal Information Service
D-RVR Data Link Runway Visual Range

13. Cost-Benefit Considerations Requirement driven Capacity Plan
Traffic Growth
Data Link Introduction
„Do Nothing“-Alternative
EAM 04
P1 Program
RVSM
VAFORIT 1
Mode S ES
The use of data link services is not the only reason for the estimated growing number of service units, realised at increasing traffic levels.
due to the phased data link implementation the 15 % Capacity Enhancement, expected from the impact of Data Link will be splitted as follows:
from 2005: 10% from the expected additional service units from 2007: 15% from the expected additional service units (further 5%)

14. Cost-Benefit Consideration still in progress
DFS is a contributor to the ongoing Link CBA.
The objective is to conduct a European-wide analysis.
The uncertainty* of early conducted cost estimations with particular focus to DFS was very high. Therefore, the introduction of Data Link Services** could not be justified by economic reasons only. * At the moment of already conducted estimations there were very few reliable sources of monetary information regarding costs and benefits. ** There was no individual investigation particular to singular data link services.

15. Summary (1)
Future ATM-concepts depend on Air-Ground Data Link Services.
Air- Ground data communications is a major component of the „ATM Strategy for 2000+“.
The benefits of Air-Ground Data Link Services were demonstrated in the framework of PHARE and during the PETAL Life Trials.
The continued use of today's operational environment will result in further frequency shortages.
The cost/ benefit-ratio could not be finally calculated. There are a lot of currently unknown factors in the equation. This leaves the risk, that the figure will not justify the need.
 The introduction of Air-Ground Data Link Services could not only be justified by a cost/ benefit-analysis.

16. Summary (2)
The migration from ACARS to VDL M2 as the next generation AOC- Data Link media seems to be decided by the Airlines and the Service Providers (SITA/ ARINC).
Service Providers already decided on installation and operation of VDL M2 Ground- Infrastructure.
Airspace capacity shortages are expected when Data Link Services are not introduced before 2006.
DFS customers are requesting Data Link Services today, in order to receive enhanced and improved overall quality of ATC Services.

17. Conclusions (1) Data Link Services
There is a strategic requirement to introduce Air- Ground Data Link services within DFS controlled airspace.
Therefore DFS introduces Air-Ground Data Link Services in a phased approach:
Phase 0 (starting 1999): Initial Data Link Applications (Result of the Projects INDAL- DATIS and -DDCL)
Phase 1 (starting 2005): non- time critical Data Link Services
depending on operational requirements:
Phase 2 (starting 2007): time critical Data Link Services

18. Conclusions (2) Data Link Services
Data Link Services (main categories only)
Phase 1 (starting 2005):
non- time critical Services
CPDLC (DCL, CIC- non time critical)
ADAP (CAP, SAP)
D-FIS (D-OTIS, D-SIGMET)
other Services (e.g. FLIPCY)
additional Phase 2 Services (optional starting 2007):
time critical Services
CPDLC (CIC-time critical)
ADAP (PPD, ADS)
D-FIS (D-RVR)
other Services.
The introduction of a specific Data Link Service requires a formal approval by the DFS senior management. A detailed cost benefit analysis will be conducted prior to the launch of each project.
All relevant ATM systems must be prepared in due time to handle Data Link Services.

19. Conclusion (3) Air-Ground Data Link Media
Non- time critical ATS Data Link- messages will use VDL M2 (medium timeframe, starting 2005)
The need for and the type of a “complementary Data- Link Media” (in addition to VDL M2) needs to be investigated and decided till In the light of the DFS- decision on Mode S Enhanced Surveillance, SSR Mode S communications will get special attention.
The operational requirement for the use of time critical ATS- Data Link- messages - and if so the type of the media - needs to be defined till 2002.