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International Civil Aviation Organization
INFORMATION PAPER
FIRST MEETING OF THE COMMUNICATIONS PANEL (CP)
Montreal, Canada, 1 – 5 December, 2014
Agenda Item 9 and 5: AOB
Update on Data Link Implementation activities in Europe
(Prepared and presented by
France, Germany, Ireland, Italy, Sweden, United Kingdom and
EUROCONTROL)
SUMMARY
This Information Paper provides an update of the ongoing data link implementation
activities in Europe using the VDL2 data link. It provides information on the observed
performance and summarizes the planned activities to address the observed issues and
the way ahead
In addition the paper recalls the agreed strategy and planning in Europe in relation to
VDL2 and the implementation of ATN/B2 applications.
1/12/14
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INTRODUCTION
1.1
Data Link implementation is a critical element of the single European sky, as it is a
fundamental pre-requisite for the implementation of a number of essential requirements as identified
in the European ATM Master Plan.
1.2
In 2009 the EU adopted the Data Link Service Implementing Rule (DLS IR) which
provided the legal basis for deployment of the Link2000+ ATS data link services in Europe over the
ATN/VDL2 infrastructure. VDL2 was the identified means of compliance as it also allowed starting
and building upon an existing infrastructure (both on the avionics side and the ground side) which was
already deployed to support the continued growth in Airline Operational Communications (AOC)
traffic.
2.
VDL2 IMPLEMENATION IN EUROPE
2.1
CPDLC services over ATN/VDL2 started in Europe in the EUROCONTROL MUAC
Centre and are presently provided by the following States: Austria, Belgium, Germany, Hungary,
Ireland, Luxembourg, Netherlands, Switzerland and the United Kingdom.
2.2
Technical problems, most often in the form of the so-called Provider Aborts (PA)
which were identified in 2007, have affected the initial implementations. Several causes of PAs have
been identified and fixes have been developed (mainly software upgrades). However these software
updates for the avionics versions flying are in various stages of being rolled out.
2.3
Some ANSPs have decided to only accept CPDLC connections from aircraft with
updated avionics in order to maintain an acceptable level of service. This control is maintained
through a white list.
2.4
AOC has been in operation for many years and airlines have used the data link
applications to support their operations. More recently AOC applications that support aircraft and
engine health monitoring have also been introduced to support improvements in efficiency and safety
of flights. Such AOC services have caused a considerable increase in AOC data, and the full impact of
which is still not known. This has led to saturation problems as current European VDL2 deployment
is over a single frequency (the CSC- Common Signalling Channel at 136.975 MHz).
2.5
The need for additional frequencies has been identified as one of the necessary steps
to help resolve the congestion of the existing frequency. The forecast for when these new frequencies
will be required has already been investigated in the past and is now also the subject of an SJU study.
Whilst it is clear that moving to multi-frequency infrastructure is needed, multifrequency should not
be considered as the definitive solution.
2.6
In summary, delays in deployment and unresolved performance and implementation
issues have led to a situation where the system currently does not fully meet the
expectations/requirements of operational CPDLC service. It is understood that AOC services
operating on the shared CSC are operating largely within service requirements.
2.7
In response to this situation, the European Commission, supported by EASA and the
SJU, have initiated a series of actions to investigate the issue. A preliminary analysis was undertaken
by EASA and the results were provided in a report published by EASA in April 2014.
2.8
Following the recommendations of the EASA Report, EC has asked SJU to undertake
additional R&D activities to provide greater insight into the issues.
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2.9
In EUROCONTROL the Data Link Central Reporting Office (DLS CRO) monitors
the performance of the end-to-end system as well as conducting a number of investigations into the
problems supporting the stakeholder (airlines, ANSPs, SJU, EASA, ) in resolving the identified issues
in relation to the PA.s.
2.10
Performance metrics are published regularly on the DLS CRO wiki and these
highlight in particular the continuing problem with ‘Provider Aborts’ and round trip delays being
above the target values. Figure 1 below shows the most recent data in relation to the PA rate.
Figure 1: Provider Abort (PA) rate
2.11
In Figure 1, the target rate1 for provider aborts is 1 PA per 100 hours of CPDLC
usage. Figure 2 below shows the technical Round Trip Delay. In Figure 2 the target for the 95 th
percentile delay is 16 seconds.
Figure 2: Technical Round Trip Delay
1
The targets are have been derived from ED120 requirements and are documented in the Link 2000+ DLS CRO Performance Monitoring
Requirements document. Document reference CFC/Datalink/PMR, edition 1.3. Available from the DLS CRO wiki.
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VDL2 INVESTIGATIONS BY SESAR JU
3.1
The SJU has launched 2 studies which constitute the first actions (Phase 1) in
response to the EASA report.
3.2
Phase 1a: Datalink Study kicked off in June 2014 and addresses the sustainability of
VDL2 in the SESAR context addressing a subset of the EASA actions including multi-frequency
VDL2 capacity vs future data load needs. The objectives of the study include:

Determine limits of capacity and performance of VDL2 to support future SESAR services

Scenarios cover the time period 2015 - 2040,

Datalink load to include AOC & ATN Baseline 2 Services

Mixed equipage in dense continental airspace scenarios to be considered

Simulations foreseen covering services, link budgets, data volumes and timing.
3.3
Phase 1b: A new Call for Tender was launched August 2014 which requests further
validations, equipment testing and flight campaigns addressing RF load, avionics performance,
ground system topology and multi-frequency options investigation. The procurement process is still
ongoing but it is hoped that the study will be launched in January 2015. Topics to be taken into
consideration in this study include:

Ground network topologies

Traffic flows and peak demand scenarios

Channel occupancy and RF Interference levels

Validation of Multi-frequency approach

Channel management and ATS Message prioritization

Network performance monitoring
4.
NETWORKING TECHNOLOGY (OSI AND IPS) CONSIDERATIONS IN EUROPE
4.1
In Europe, the first set of data link services as covered by the DLS IR have been
implemented using the ATN/OSI protocols.
4.2
Currently, data link implementation is actively pursued primarily in Europe and US.
While there is divergence in the planning of the initial set of data link services between Europe and
US, there is now agreement between US and Europe (in the context of the RTCA and EUROCAE
SC214 and WG78 committees) on the next set of data link applications to be implemented.
4.3
The converged set of future data link applications is referred to as ATN Baseline 2
(ATN/B2) applications. Europe has been actively supporting the work in the WG78/SC214 groups to
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specify the required performance of the ATN/B2 applications. In Europe, it is planned to provide
ATN/B2 applications over VDL2 and ATN/OSI.
4.4
Europe is also following the ongoing discussions in particular in AEEC about the
future use of OSI and IPS.
4.5
Europe is planning to continue the VDL2 network rollout over OSI as there have so
far been no clear benefits identified to support consideration of using VDL2 over IPS.
4.6
In relation to IPS, Europe has been very supportive of the ICAO IPS work. IPS is
already implemented in Europe for the ground side. For the air/ground side, Europe aims to
implement IPS with the new links such AeroMACS, new SATCOM and new terrestrial (LDACS)
system.
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