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close this book The Courier N°139 May- June 1993- Dossier: Factors and development - Country Reports: Trinidad and Tobago : Zimbabwe
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View the document Aeronautical satellite telecommunications for Central and Western Africa


Aeronautical satellite telecommunications for Central and Western Africa

by Edmund APPELBAUM *


In 1985, concern over levels of safety in Nigerian airspace were such that, at the request of the Nigerian Government, the UNDP financed a study on how aviation standards could be brought up to internationally accepted levels.

The International Civil Aviation Organisation (ICAO), which carried out the study, pointed out that among the most alarming problems were inadequate air to ground communications and the virtual absence of communications with neighbouring countries by means of either direct speech or 'Aeronautical Fixed Telecommunication Network' (AFTN) circuits.

In an effort to determine the optimum system of communication between airports, the ICAO considered conventional means such as microwave links and high frequency but it finally recommended the use of satellite facilities offered by INTELSAT (the International Telecommunications Satellite Organisation).

A request to finance a project along these lines was submitted to the EC Commission. The national authorising officers of the region, at their meeting with the Commission in Cotonou in May 1987, gave priority to the use of Lome III regional funds for measures to improve air traffic safety in Central and Western Africa.

A feasibility study produced by International Aeradio Ltd (IAL) in January 1989, proposed that a closed digital network - using INTELSAT facilities - be established between eight countries and 15 airports in the region, with communications limited to air traffic control matters. In July of the same year,, a study for detailed design, specifications, preparation of the tender documents and adjudication was awarded to IAL.

However, the launching of a call for i international tender could only take place once a series of preliminary requirements had been fulfilled by each of the eight ' states participating in the project. INTELSAT regulations only allow contracts to be made with INTELSAT signatories, who are normally the PTT or telecommunications organisations of the countries concerned. 1As a result, close cooperation between the eight countries was necessary at the preparatory stage. Within each country, the INTELSAT signatory had to inform the organisation of its firm intention to participate in such a network. Furthermore, individual operating agreements between the INTELSAT signatory and the local civil aviation authority had to be signed, allowing the latter to own, operate and maintain the earth stations at a rate specified by INTELSAT plus a 5% allowance for the PTT's overhead expenses.

The problems of coordination, when so many different authorities are involved, may explain why, although INTELSAT has since 1973 offered a full range of services which are specially designed for developing countries, these have not hitherto been used for civil aviation purposes.

Another complication which arose during the project implementation phase was in finding a Regional Authorising Officer (RAO) for the eight countries, in accordance with normal EDF procedures. The solution finally found was to entrust the responsibility for preparing, implementing and operating the project to three RAOs. These were: for Nigeria, the Federal Civil Aviation Authority; for Ghana, the Ghana Civil Aviation Authority, and for the remaining six countries, the 'Agence pour la Securite de la Navigation Aerienne en Afrique et Madagascar' (ASECNA).

In practice, this division of responsibility meant that the Financing Agreement had to be signed by all three RAOs and the contract for the 15 earth stations had to be divided into three subcontracts covering Ghana, Nigeria and the ASECNA members.

Although the Commission is represented in all the countries concerned, it took some time (from May 1990 to June 1991) to carry out the preliminary procedures between INTELSAT, the PTTs and the civil aviation authorities. An international tender for manufacture, supply, installation and training was launched in July 1991 and, following the award of contracts, work commenced in July of the following year. The implementation period is fixed at 22 months and the aim, therefore, is for the whole closed network to be operational by May 1994.

Project description

The project will enable safe and continuous operation of Aeronautical Fixed Services by creating independent links (the so-called 'closed system') between the eight countries and 15 airports in the area covered by the 'Flight Information Regions' (FIRs) of Niamey, N'Djamena, Accra, Brazzaville and Kano as well as the new Lagos FIR which is due to come into operation in 1993. These links will permit direct speech between the airports covered by the system as well as transmission of air-traffic control and meteorological data. In addition, in Nigeria the project will significantly improve groundair communications through extended range VHF schemes. The project overall, therefore, has two components - a regional one and a national (Nigerian) one.

The regional component consists of nine earth stations to be installed at Accra, Brazzaville, Douala, Libreville, N'Djamena, Bangui, Niamey, Kano and Lagos. Kano will be the coordination centre of the network and will, therefore, have a direct connection with the INTELSAT operations centre in Washington.

Two stations will be responsible for supervision and remote maintenance monitoring, Kano for Nigeria and Ghana, and Brazzaville for the ASECNA countries. All stations will be linked by direct speech communications through an INTELSAT satellite.

Nigeria is the main focus of the network and, as stated earlier, there is a need to improve air traffic safety over this country. This will be achieved by the installation of six earth stations, together with the associated communications equipment, in Abuja, Ilorin, Jos, Maiduguri, Port Harcourt and Sokoto. Each of these centres, together with Kano and Lagos, will also receive VHF stations to provide extended coverage for Nigeria's airspace.

The project includes provision for technical assistance to be provided by the supplier of the earth stations for the first four years of operation. One expert will be based at Kano and a second at Brazzaville.

The satellite network

Training of operators for the network is included in the project, as well as training for engineers on equipment for Nigeria's aviation systems.

As this is the first project of its kind in the world, a test period of 18 months is foreseen. During this time, evaluation of the reliability and effectiveness of the complete closed network will be carried out by independent experts.

The project is being financed with grants, consisting of ECU 18.5million from Lome III regional funds and ECU 20.0 million from Nigeria's National Indicative Programme under Lome IV.


The improvement of aeronautical communications throughout the region will clearly have significant positive effects, particularly as regards safety and regularity of air traffic. The result should be better flight operations, as well as enhanced passenger comfort and convenience, leading to more comprehensive economic and other benefits for operators and travellers alike.

More specifically, the following improvements may be expected:

Changes to Air Tratfic Control Separation Standards. The standards applied to keep aircraft apart in the skies are based on a variety of factors, but communications clearly play an important part. With enhanced facilities, there will certainly be a strong case for reviewing current standards since it should be possible to handle more aircraft in a given area without compromising safety. In addition, the application of common separation standards throughout the region should simplify and expedite traffic flow.

International Air Traffic System Liaison. There should be an improvement in flight regularity, particularly for scheduled operations. To take the example of aircraft transiting across a particular Flight Information Region, given that efficient communications between neighbouring flight information centres are the basis for transferring control of aircraft as they cross international FIR boundaries, guaranteed communications should allow them to proceed unhindered. In addition, where so-called 'flow control measures' are necessary (which might, for example, mean delaying takeoff times at the airport of departure), good communications can ensure that these are more accurately and efficiently achieved. This should help, in particular, to avoid time-consuming and costly 'holding' delays in which an aircraft is forced to stay in the air burning fuel until a landing slot is available.

Routing flexibility. Although airlines will naturally choose the most economic route wherever possible, there are occasions when alternative routing is desirable for operational reasons. Immediate liaison between different air traffic systems will ensure a more effective and coordinated response in such situations.

Weather routing. Similar benefits can be envisaged in respect of reroutings which are required because of adverse weather conditions.

Cruising leyels. The achievement of optimum cruising heights is often hindered because of inability to ensure that there has been proper liaison regarding level changes. When such liaison is assured, the result can be significant economies for the operators.

Diversions. These are unavoidable from time to time, but proper communications ensure that they can be slotted in with minimal disruption.

information. Clearly, a better system of liaison will also mean that information which is critical for flight planning can be passed on to operators, while passengers too can be better informed.

Departure delays. Delays in obtaining take-off clearance - which can be very expensive for the airlines once the aircraft has started up, should be alleviated by the new system.

Airspace congestion. This is not currently a serious problem in the West Africa region but efficient communications are clearly beneficial in improving traffic flow more generally and should reduce problems in the event of any future increase in air traffic.

Finally, as regards the operating costs of the new system, there will obviously be financial implications for the civil aviation authorities in the eight countries covered. The total rental costs for the satellite circuits associated with the new stations amount to approximately $164 000 per annum. ($71 000 for the six ASECNA countries, $8000 for Ghana and $85 000 for Nigeria). Annual replacement costs, covering depreciation and spare parts, are estimated at $1.8 million. It should be possible to recover these costs from the air carriers, given that they will benefit from substantial savings once the system is operational.