Transcript SITA Presentation

Integrated information and
telecommunications solutions
AIRCOM Implementation VHF Digital Link
Presented by Philip Clinch
to ATN 2001 Conference
19 September 2001
Integrated information and
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SITA VHF Digital Link Objectives
SITA has been working on VDL for 10 years to promote
Air Traffic Service provider use of aircraft data links
by defining a new VHF data link system whose
design is approved by the ATS providers and which
can at the same time replace the VHF ACARS
system we use today to serve over 100 aircraft
operators with 5000 aircraft.
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VHF ACARS use for ATS applications
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VHF AIRCOM was used by Eurocontrol PETAL 1
which installed a very basic ATS application on
pre-delivery AIRBUS aircraft flying between the
Toulouse and Hamburg factories.
When Eurocontrol launched PETAL phase 2 the
CPDLC system was intended to communicate with
aircraft having ATN avionics. SITA recommended
mitigating the risk of ATN avionics delivery delays
by opening up to aircraft with FANS-1/A CPDLC
and Eurocontrol connected the CPDLC system to
the VHF AIRCOM network.
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PETAL Benefits from incorporating FANS
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The benefit to the PETAL project of opening up to FANS
aircraft was to obtain a number of CPDLC equipped
aircraft sufficient to maintain controller familiarity with
data link.
– Since January 2000 an average of 10 FANS flights per
day have conducted CPDLC with controllers at
Eurocontrol Maastricht.
– FANS aircraft were the only PETAL participants in 2000
and they still represent 75% of the flights since the
NEAN aircraft restarted participation.
– PETAL CPDLC communications with FANS aircraft was
critical to keeping up the project momentum.
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VHF data link upgrade requirement
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While VHF ACARS is supporting CPDLC in the Petal 2
trial its performance is constrained because, when it
was implemented in 1978 to minimize the avionics
cost it used VHF analog voice radios.
– The VHF analog ACARS data rate of 2.4 kbit/sec is
not enough for the daily average of over 3000 aircraft
that use the service in Europe and the eastern USA.
– Aircraft data links with higher capacity would be easier
to implement in other radio bands not managed by
aviation authorities but this protection makes the VHF
band attractive to ATS providers and their use of VHF
data link triggered the definition of a new system.
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VHF Digital Link Mode 2
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SITA contributed to the ICAO decision in 1991 to task the
Aeronautical Mobile Communications Panel with defining
ATN subnetwork service provision by a VHF data link.
– AMCP defined a common subnetwork protocol using a
Mode 1 modulation scheme compatible with analog radios
for validation purposes and a high speed Mode 2 modulation
scheme requiring the use of digital radios.
– AMCP decided VDL Mode 2 should use the modulation
scheme selected by the the FAA for a system to support
digitized voice which they called VDL Mode 3.
– AMCP did not specify VDL Mode 2 provision of aircraft to
aircraft links because they are not used in the ATN.
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SITA Implementation of VDL Mode 2
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SITA has started deploying a ground station that handles
VDL Mode 2 and VHF analog ACARS.
– SITA has since October 2000 installed our first VDL ground
stations at Rockwell Collins, Honeywell, AIRBUS, Paris and
Amsterdam.
– Collins carried out VDL tests in October 2000 and AIRBUS
in September 2001 carried out their first tests of VDL in the
ATSU using the SITA VDL station at Toulouse.
– The SITA VDL service supports an AEEC defined ACARS
over AVLC (AOA) service which minimizes the cost of the
airborne implementation while providing a platform for the
subsequent addition of an ATN router and CPDLC.
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VDL Mode 2 Benefits
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SITA input to VDL Mode 2 standardization ensured its
implementation remained feasible by focusing on the
objective or replacing VHF ACARS.
– VDL Mode 2 is the only VDL mode that can credibly take over
the ACARS support for ATS and AOC enabling the ATN
CPDLC data link business case to profit from the value
generated by increasing AOC data link capacity.
– VDL Mode 3 support for data link is planned by the FAA for
2011, a generation after VDL Mode 2, and even then VDL
Mode 3 would probably not support AOC data link.
– VDL Mode 4 implementation would be driven by ADS-B but it
could not provide the reliability needed for ADS-B if was also
supporting engine reports and passenger lists.
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VDL Mode 2 Institutional Issues
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The VDL Mode 2 technical issues have been resolved
but debate continues over the service provider role.
– The Eurocontrol Link 2000+ and FAA CPDLC programs
assume that VDL Mode 2 service will be provided by the
current ACARS service providers and ATS providers will
pay for the traffic they exchange with aircraft.
– Some ATS providers are deploying or housing the VDL
Mode 2 stations in their territory and partnering with an
airline service provider to deliver AOC traffic.
– The dual role of ATS providers as VDL Mode 2 users
and providers makes resolution complicated.
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Conclusion
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VDL Mode 2 offers an aircraft to ground station data
link with the highest data rate possible in a 25 kHz
VHF channel and will be installed on most new jet
aircraft delivered in the next decade.
VDL Mode 2 competes with satellite data link and
the other VDL modes have different competitors:
– VDL Mode 3 competes with VHF analog voice using
8.33 kHz channels.
– VDL Mode 4 competes with Mode S and UAT to
support an ADS-B service.