FINAL REPORT - Stakeholders - Ofcom

channel, and would further increase the demand on the frequency. Note however that
TIS-B could in theory operate on the 1030MHz channel (underutilised at present) – here,
cross-channel usage leads to spectrum efficiency.
3.3.11 Conclusions and recommendations
The key developments which influence use of the 1030/1090 MHz frequencies are:
• The transfer to Mode S from current SSR. As well as a number of operational
benefits, this provides a reduction in the level of interference and makes it
possible to maintain SSR services as traffic grows.
• The implementation of ADS-B services via 1090 extended squitter, which whilst
offering potential operational benefits, will increase the use of the 1090 MHz
spectrum and possibly saturate.
Recommendations 3.15 to 3.17 below apply to the efficient use by SSR of the 1030/1090
MHz frequencies
Recommendation 3.15: Ofcom should satisfy themselves that the CAA has taken the
appropriate steps to ensure that the tailoring of SSR Pulse Repetition Frequencies
conforms to ICAO recommendations.
Recommendation 3.16: The implementation of Mode S SSR in the UK should be
encouraged (allowing selective addressing and potentially fewer replies) coupled with
implementation of measures to encourage equipage and the appropriate implementation
of controller tools which use the resulting data.
Recommendation 3.17: Mode S Extended Squitter implementation – Ofcom should work
with the CAA in ensuring that data downlinked from the aircraft is not superfluous to
requirements. In particular this means reviewing the need for regular broadcast of DAPs.
Socio-economic factors
Upgrade of the commercial fleet is a costly exercise but one for which there is reasonable
support. The first stage of upgrade to provide elementary surveillance is already covered
by a mandate, and this is likely to be extended to cover enhanced surveillance. Hence,
pricing measures are unlikely to be required.
Upgrade of GA aircraft is also highly cost sensitive and upgrade is generally resisted by
the GA fleet. The CAA’s intention is to mandate equipage for elementary surveillance for
all aircraft by 2008. The costs this will impose on the GA fleet are currently unknown
although it might be expected to be in the region of £1000 to £3000 6 . This amounts to a
total GA fleet cost of between £6M and £18M assuming a fleet of 6,200 aircraft. It may be
necessary to provide support for GA users in order to facilitate the equipage.
The next two recommendations apply to the introduction of new services on the 1090
MHz frequency.
Recommendation 3.18: The 1090MHz channel will be severely constrained in the
medium term. A review of the future use of this band should be carried out.
The review should ensure that any new applications meet clearly defined operational
requirements; if not, studies should be performed to assess the potential benefit against
6 CAA are currently sponsoring a programme to develop a low cost Mode S/1090 ES capable
transponder. The target cost, subject to verification by the programme, is below £1000.
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