AERONAUTICAL COMMUNICATIONS PANEL (ACP)
Working Group C – 6th meeting
Toulouse, France
20 – 24 October 2003
Agenda items 5: VHF Spectrum Congestion
Evolution of the AM(R)S VHF capacity in the ECAC States
Presented by EUROCONTROL
SUMMARY
This paper presents the result of a simulation which has been undertaken in 2002 to assess the VHF AM(R)S demand Vs the VHF frequency availability in the ECAC States.
1.Background
As a result of the increasing VHF frequency congestion experienced in some European States in the 90’s, the ICAO recommended the introduction of 8.33 kHz spacing in congested European airspace (EUR RAN meeting - Vienna 1994, SP/COM/OPS/95, Montreal March-April 1995).
The 25 kHz to 8.33 kHz conversion started during an initial phase in airspace over FL 245 of 7 States by October 99. It was latter decided to extend the conversion to 22 additional States over FL 245 as from October 2002.
Recently (December 2002), the ICAO/EANPG 44 decided to proceed with the vertical expansion of the 8.33 kHz channel spacing down to FL195 as from 2006, and as required in selected terminal control areas (TMA)s and control zones (CTR)s where individual States would determine this to be a practical measure for alleviating VHF local congestion. The ICAO/EANPG agreed also on the principle to consider operation of 8.33 in designated controlled airspace in the ICAO EUR Region from 2009 onwards in case of severe congestion.
Despite all these measures, VHF congestion is still expected to be experienced again in some European States.
This paper presents a prevision of the forecast frequency demand and a simulation of the available spectrum capacity in the VHF AM(R)S band up to mid of next decade.
It is based on a Paper [Ref 1] which was approved by the EUROCONTROL ACG[1] 16 (May 2002) in the framework of the decision process to extend the 8.33 in the lower airspace.
2.Aviation Traffic forecast
As a first step a model of the aviation traffic evolution was established based on STATFOR[2] forecast figures.
Fig 1 – Model of Aviation Traffic evolution in the ECAC States
The computation used Feb 2002 figures (which were the latest figures available at the date of the computation). Two cases were identified (a worst case and a best case scenario) (see figure 1 - bleu diamond shape).
From the results, it was noticed that the traffic would roughly increase on a linear basis in the coming years.
It was then decided to compare this prediction with another prediction based on information which were available before September 2001. July 2001 figures were computed (see figure 1 - green triangles shape). Based on this second computation, the same conclusions were drawn on linear increase of the traffic although a 2-years delay was identified.
Therefore, it was decided to apply a linear model increase on the aviation traffic.
3.Frequency demand evolution
From an Eurocontrol study on mobile communication operating concept applicable up to 2015 [Ref 2], it results that no fundamental change would appear during this period in the way the aircraft are managed by the controller.
For voice communication, this will still result in the association of one channel for each controller and since no revolution is expected for the voice communication systems in this timeframe, it will result in one VHF frequency for each controller.
The ever increasing usage of datalink is not foreseen to change this tendency although a part of the exchange will be supported by datalink. This will only result in less frequently used voice channel, however one voice channel will still have to be assigned to the controller.
To be able to cater with the linear increase in aviation traffic, the number of controllers has to be increased linearly as well (note: although there is not a general consensus on this aspect).
As a consequence, it was decided to apply a linear model for the VHF Frequency-demand increase for the coming years (up to 2015).
The linear increase of the demand was also confirmed by the analysis of the past demand.
Note: STATFOR identified a 2 years delay in aviation traffic. However, taking into account current projects (e.g. implementation of VDL. CEATS), which would require additional spectrum, it has been decided to not integrate this delay in the VHF frequency requirement evolution.
4.Frequency assignment success
A computation was undertaken based on a tool developed by Eurocontrol (SENSI[3]). The linear frequency demand model was applied.
Fig 2 – VHF Frequency demand Vs VHF Freq availability in Europe
The line as identified by a “1” in a square represents the linear frequency demand.
The curve identified with a “2” in a square is roughly similar to the scenario which has been endorsed by the EANPG (horizontal extension to 29 states, vertical extension i.e. 8.33 applicable over FL 195, and 8.33 operation in major CTR and TMA). According this scenario, around 60% of the new requirements will not get a frequency assigned in the middle on the next decade.
The curve identified with a “3” in a square is related to a scenario related to the introduction of 8.33 in all the controlled airspace. This is a very constraining scenario since a significant part of VFR and military aircraft should be 8.33 converted. In this ambitious scenario, yet 40% of the new requirements would not get a frequency assigned in the middle on the next decade.
Note: As an outcome of the ICAO/EANPG 44, it was decided to proceed to the vertical extension of 8.33 in a stepped approach. This would result in a slightly more pessimistic simulation results.
5.Conclusions
As a conclusion of the simulation of the frequency demand Vs the available VHF AM(R)S capacity up to 2015, the WG C is invited to note the expected continuous AM(R)S VHF congestion expected to be experienced in Europe, despite the extension of the 8.33 system.
Reference document
[Ref 1]: AP/ACG/16/27 (08/05/2002) – High-Level Communications Group Report on VHF Congestion
[Ref 2]: MACONDO - Operating Concept for the future mobile communication infrastructure
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[1] The ACG (ATM/CNS Consultancy Group) is a High Level Management Group composed of Eurocontrol Stakeholders representatives aiming at advising Eurocontrol on ATM aspects
[2] Air Traffic Statistics and Forecast (STATFOR) is the EUROCONTROL service in charge of establishing and providing statistics and forecasts on air traffic in Europe. STATFOR has been established by EUROCONTROL in 1967
[3]SENSI is a software tool developed for Eurocontrol and used for predicting the VHF spectrum occupancy in the future. As input the software requires a database which reflects the current spectrum situation, a scenario which simulates the frequency demand on a long period based on a statistical model which has been established considering the demands over the past years. The computation uses the frequency protection criteria and rules which are applied for frequency planning in Europe.
The software has been used successfully for the 8.33 and other.