AMCP WG/WP33
AERONAUTICAL MOBILE COMMUNICATIONS PANEL (AMCP)
Working Group of the Whole
Montreal, Canada
21-24 May, 2002
UK Statement on UAT
Presented by the U.S. Member
SUMMARY
At the Anchorage meeting of AMCP/WGC, a statement of support for the development of UAT SARPS was submitted by David Farncombe, UK AMCP member. The meeting is invited to note this paper in their deliberations.
AMCP WGC/3-WP19
E-mail message from David Farncombe on UAT SARPs
From: FARNCOMBE David [
Sent: Thursday, 11 October 2001 6:17 PM
To: 'Van Den Boogaard Kors'; 'Alessandro Capretti'
Cc: 'Phillips Brent'; 'Chris Moody'
Subject: UAT SARPS
Kors, Alessandro,
Brent has kindly passed me direct copies of his WPs 10 and 12 which invite
the WG C to recommend the development of SARPs for UAT.
As the Working Group may recall, I did not support the adoption of SARPS for
VDL Mode 4 at AMCP 7 and was forced to ensure that my minority view was
included in the Report of AMCP/7. For convenience I will repeat the wording
of this minority view as contained in Para 2.2.2.6.6 and the preceding
paragraph of the AMCP 7 Report:
2.2.2.6.5. On the basis of the information provided, the meeting decided
that there was a justified need for VDL Mode 4 SARPs.
2.2.2.6.6. This conclusion was not shared by (one member), who maintained
that AMCP had not yet satisfactorily completed Task No CNS-9603 since it
implicitly required an evaluation of candidate data links to be completed
before any specific recommendations were made. In his opinion, AMCP would
not be in a position to make a recommendation, with any degree of
confidence, until the complete set of operational requirements for ADS-B
has been completed by ADSP. This is not now expected before 2002. The
Member particularly noted that this view had been shared by the ANC when
they reviewed the report of AMCP/5. At that time, they too had accepted that
no decision on which data link should be used for ADS-B until the
operational requirements for ADS-B had been finalised by ADS-B. The member
did not support the accord reached by the VDL Mode 4 Validation Sub-group
and SICASP Working Group 2 that the performance characteristics of VDL Mode
4 and Mode S Extend Squitter were complementary. In his opinion, no such
decision could be made on this subject until the requirements for ADS-B had
been finalised by ADSP. Furthermore, in the event that the ADS-B
requirements could not be met by either VDL Mode 4 or Mode S Extended
Squitter, he considered that the logical conclusion would be to reject both
systems rather than proliferate standards. The appropriate action for ICAO
would then be to concentrate on the development of SARPs for a single
surveillance data link that would be capable of meeting the complete range
of requirements. The member drew particular attention to the fact that a
number of programmes were underway in Europe and the USA to carry out a
comparative evaluation of VDL Mode 4, Mode S Extended Squitter and UAT as
candidate data links for ADS-B applications. These programmes included
practical evaluations and were expected to provide results to allow a
decision on the choice of data link for ADS-B to be made in 2001. The
member therefore considered that it was premature for AMCP to make any
recommendations regarding SARPs for VDL Mode 4 until the requirements for
ADS-B had been developed by ADSP and the results of the evaluation
programmes being carried out in Europe and the USA were available.
Accordingly this member could not support any recommendation regarding the
adoption of VDL Mode 4 SARPs at the present time.
Having reviewed the US Papers, I remain convinced that my (albeit minority)
view was fundamentally correct and the decision to recommend for adoption
the SARPs for VDL Mode 4 as an ICAO global standard was flawed. As a result
ICAO has set an unfortunate precedent in that it is prepared to agree SARPs
for systems without a clear idea of the required operational requirements
or an objective analysis of the candidate technical options. It therefore
accepted the risk that superior systems would be required and developed, and
standards would be proliferated.
From a UK perspective, I have always supported the UAT concept. Although
our operational strategy does not envisage the use of ADS-B in domestic
airspace within the next 10 years, the concept has some long term promise
but will require a system that is compatible with the capacity and integrity
requirements of high traffic density areas. It must also have the
flexibility to accommodate changes in requirements as operational concepts
are developed to improve ATM system performance and cater for capacity
growth. A narrow band system operating in the VHF band, requiring
multi-channel operation in order to meet capacity requirements, is an
inappropriate technology and cannot be supported. Adapting the current Mode
S SSR system to provide the broadcast data link capability appears to have
limitations. It is surely axiomatic that the correct approach is to develop
a system that has been designed for purpose, employs a wide band channel
and is unfettered by the constraints of the VHF Band.
My assessment of the US papers is that UAT does indeed emerge as a superior
data link to the VDL Mode 4 and Mode S Extended Squitter systems. I do not
consider the fact that these systems are already in Annex 10 to be an issue
since the proliferation of standards was inevitable following AMCP/7. The
civil aviation community should be given the ability to select the best
system for its needs and not be constrained by premature and immature
decisions. I therefore fully support the recommendations that the
development of UAT SARPs be initiated. I also consider that this would be a
valid activity under ANC Task No CNS 9603 and should commence immediately.
I would be grateful if you would bring these views to the attention of WG C3
in my absence. Please introduce this e-mail as a Working Paper if you wish.
Regards.
David Farncombe
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