By: E. O. ONASANYA

INTRODUCTION

Airspace Management (ASM), the purpose of which is to manage airspace - a scarce
resource - as efficiently as possible in order to satisfy its many users, both civil and
military. The service concerns both the way airspace is allocated to its various users (by
means of routes, flight levels, etc.) and the way in which it is structured in order to provide air traffic services. The International Civil Aviation Organisation in the ATS Planning Manual stated, "in planning and management of airspace, States should aim to promote flight safety, provide sufficient capacity to meet normal traffic demands, ensure maximum utilization of airspace, ensure compatibility with international developments, and balance the legitimate, but sometimes conflicting requirements of all users".

Therefore, in its basic configuration an effective airspace management must provide:

1. Information and/or instructions with respect to aircraft safety and efficiency of operation.

2. Navigational guidance to aircraft along designated routes and at airports.

3. Meteorological information to prevent aircraft operation in uneconomical or dangerous conditions.

4. Assistance to aircraft in need of search and rescue aid.

5. System status information to identify the reliability and availability of services, facilities and specific system components.

6. Adequate room for military operation so as not to impede civil aviation.

In addition the government must assure the users of the airspace system that it is reliable and without risk. These requirements are generally accomplished through the application of internationally agreed standards and procedures and through a continuous monitoring and supervision (safety oversight) of all air navigation activities.

PLANNING

International agreed standards and procedures relating to airspace management are contained in the various Annexes to the Chicago Convention. States, while planning at the national level, refer to these documents to determine the quality and quantity of the services they are to provide and the infrastructure to support such services. At the regional level, in order to ensure an integrated and harmonious air traffic management system that would enhance
seamless navigation, regional planning group (RPGs) are mandated to specify the services,
facilities and procedure that will enable States meet biennially to review the status of
implementation of specified services and facilities arising from regional air navigation (RAN) meetings. Generally, the planning and operation of air traffic management is carried out on a national basis with varying degrees of coordination with ICAO regional offices and the contiguous States. To ensure an efficient development of air traffic management system and cost control, States are obliged to develop their Master Plan that will serve as a road map for the development of air navigation services. The plan would normally define:

STRUCTURE

An airspace system contains two basic elements. The first is the structure which defines the dimensions of the airspace and names various elements such as control zones, terminal manoeuvring areas, air traffic services routes, etc. The second is the airspace classification. The application of any classification to an airspace structure determines the operating rules, the level of service provided within the structure and, to some extent, the infrastructure requirements. The separation of rules from the structure provides the flexibility to reclassify - thus change the rules - for any portion of the structure without having to deal with the cumbersome process of restructuring. Airspace restructuring is a complex process that should be dictated by demands of airspace users, regional or national plan, lack of airspace capacity, or availability of improved technologies (aircraft and ATC). Airspace restructuring would normally be part of an overall air traffic services plan.

TECHNOLOGICAL RESOURCES

The airspace structure and its management are greatly influenced by the equipment used to support air traffic services. According to its function, equipment will fall into one of three separate "domains".

Communications - includes all technology for transferring information needed for navigation, surveillance and air traffic management. "Aero-mobile" is distinct from "Aero-fixed", but each has separate networks both speech and data transmission;

Navigation- refers to all equipment that facilitates an en route navigation by aircraft along the routes they have to fly;

Surveillance- means all technologies that enable ground-based air traffic controllers to keep track of aircraft. The use of radar is now enhanced by the introduction of radar data processing system (RDPS).

THE LEVEL AND QUALITY OF AIR TRAFFIC SERVICES

There are three main criteria by which the success of an ATM system can be judged:

The system is assessed against these criteria using performance indicators:

Level of safety

The number of airmisses recorded within a national airspace must be stable over a period of many years (about 20years) or decrease disproportional to the number of traffic handled by the ATC system.

Factors influencing airspace capacity

"Airspace capacity" means the maximum number of aircraft that can be handled simultaneously by a typical sector while maintaining an acceptable safety level. Capacity will therefore depend on: The minimum separation between aircraft, and hence the maximum potential number of movement at any one time, and

The size of the sector, in terms of the volume of airspace controlled.

Capacity can be improved by increasing the number of flights handled in the sector; by decreasing their separation; and by reducing the size of the sector's airspace while maintaining the number of flights controlled. The separation between aircraft depends on several factors. The principal one is the criteria applied for procedural or radar separation. Standards for all radar subsystems are set by criteria for the performance of the radar sensor, and the central data processing system. In the procedural environment, the accuracy, reliability, availability and integrity of the navigational facilities (which depends largely on strict adherence to manufacturer's installation parameters and calibration schedule, and adequate power supply) affect the criteria applied. Other factors may affect the ATC system and hence the separation minima.

Communications: It is essential to have proper means of communication, with proper coverage and performance, which always allow immediate contact with aircraft.

Meteorology: Adverse weather conditions can mean that wider separation distances has to be allowed between aircraft. Airspace management and procedures: This means having a type of airspace structure that has the maximum flexibility to adapt to different separation requirements.

The human element: This includes pilots, who must be able to monitor and respond promptly to controllers' instructions, as well as the controllers themselves. The extent of controllers' expertise, experience and stamina are critical factors when establishing the maximum workload they can cope with.

Assessing the causes of ATC delays

Delays affect both aircraft operators, because increased flight times directly affect airlines' costs and passengers in terms of inconvenience and reduced reliability of flying compared to other means of travel. Delays also means that the airspace is not used effectively, since the effect is to spread the same flow of flights over a longer period; and the resulting increase in ATC operators' cost per kilometer flown is directly reflected in user charges. Delays survey should be done regularly (on monthly or quarterly basis) to determine the causal factors. Survey is useful in that it:

1. Samples the delays incurred by major international carriers for all their international flights - a particularly important sector of that market.

2. Shows historic trends for different causes of delay; and whether they are related directly to ATC operations, or more indirectly through flow restrictions, industrial action etc.

3. Attempts to draw conclusions about the extent to which delays are attributable to weaknesses in the ATS structure, in terms of capacity shortages resulting from lack of technical or human resources.

En route charges

Route charges are levied for the use of en route air navigation facilities and services. The route charges recover the costs incurred by Air Traffic Control. Organizations for en route air navigation services. The overall charge exacted by a State equates to the sum of individual charges for flights that have entered the airspace of that State. The individual charge for a flight is calculated by multiplying the national unit rate of charge by the number of "service units" of that flight. For each country, the national unit of charge is fixed each year by dividing the national en route facility cost-base by the total number of "service units" in that country's airspace in that year. "Unit rate of charge" for a year are fixed at the end of the previous year, on the basis of actual costs. There is a mechanism that allows any consequent disparity to be adjusted subsequently. These values must refer only to chargeable flights. Some flights are usually exempted - such as those aircraft under 2 tons, State aircraft, SAP flights, training flights and navigational aids check flights.

Development of methods of economic analysis

As seen earlier, there is a price to be paid for the development of capacity and the reduction of inefficiencies, and the economic viability of certain technical options cannot be guaranteed in advance. As seems to be the case with most ATM equipment plans and investment decisions, the decisions are based on purely operational considerations. Little is known of the cost of implementing it and the improvements that may be expected as a result have not always been quantified. There is a risk that this shortcoming will have even more serious consequences when it comes to choosing new concepts or deciding on the implementation of new technologies.

OVERVIEW OF THE NIGERIAN EXPERIENCE

The development of basic airspace infrastructure such as communications, navigation and surveillance to a large extent determine the level of service provided to airspace users. A developed infrastructure invariably enhances safe and efficient airspace management while undeveloped system creates gaps that lead to unsafe operations. The Nigerian airspace had in the past been labeled "unsafe" by airspace users primarily due to lack of communications and navigational aids.

Communications

One of the basic requirements for efficient airspace management is VHP coverage of the national airspace from the base of the ATS routes and above; air traffic direct speech (ATS/DS) circuits between the ATC Center and the station under the center. Up till today these requirements have not been achieved. This is despite the installation of satellite communications (SATCOM) in eight Nigerian airports including remote control air-ground stations. The SATCOM project itself has not been completed, that is, the Ilorin station. This is a project that has been completed in other parts of the western African sub-region over five years I ago. Other countries that benefited from the EU 4 sponsorship have since implemented Very Small Aperture Terminal (VSAT) to ensure total coverage of their national airspace. However, it must be acknowledged that communications has improved in the airspace arising from the completion of most aspects of the EU SATCOM project.

Navigation

The navigation aids distribution in Nigeria is inadequate to build an efficient air traffic services network that meets the aspiration of today's operations. They are dispersed making the width of the routes rather wide. This affects the utilization of airspace capacity. In the past the navaids often broke down. This led the then FCAA to issue guideline on the need for aircraft operators in the Nigerian airspace to carry GPS as supplemental navigation aid. This was when many countries in the world had not really appreciated the future role of GPS in the global air navigation system. New navaids and landing aids are being installed at nearly all the airports in Nigeria. Unfortunately, some of them have started to breakdown. It is necessary to complete the installation of navaids as soon as possible.

Surveillance

Six terminal radar stations were installed in the country in the late 1970s. None of them is serviceable today. The Lagos and Abuja radar stations are being refurbished as a stop-gap measure before the implementation of total radar coverage of the national airspace. It is arguable whether radar should be implemented to cover the national airspace considering the traffic level in the airspace. It is unarguable however that radar needs to be implemented in pertain TMAs to reduce the delays now being experienced by airlines. We need to recognize that the automation of air traffic services processes starts in many cases with the installation of radar. In other words, radar promotes the automation of ATS.

Air Traffic Services

In the recent past, the air traffic services provided in Nigeria was rather rudimentary. This was before the test-run of area control service in Kano Sector of the Flight Information Region (FIR). Even then, coordination of traffic among ATS units is still difficult. It is obvious that air traffic management is still inefficient. Airmiss incidents and delays are becoming, once again, major problems in some of our busy TMAs. Airlines sometimes experience up to one and a half hours delay in Abuja. This has more to do with capacity constraints. The establishment of ACC will allow for coordination of traffic and proper management.

Research and Development

The importance of research in the development of airspace management has not been given any priority. This is another major reason why air traffic management is still, to some extent, elementary in Nigeria. The problem of airmisses, delays and capacity constraints should be subjected to studies. Problems must be assessed scientifically with a view to eliminating them. The work and rest scheme and stress management programme of the organization affect the well being of the ATCO. For instance, the maximum number of traffic that should be handled by an ATCO in any particular sector has not been defined. So is the number of hours he has to rest during a shift period or between shifts etc. All these impact seriously on the health of the ATCO.

Investment Policy

The development of infrastructure (and equipment procurement) has been haphazard in the past and not based on any thought out plan. Investment decisions have been based on
operational considerations. Proper cost/benefit analysis is not always carried out. This attitude might be borne out of the fact that the government provides capital project costs and the airspace users are not owed any explanation as to how the funds are disbursed. However this attitude must change when full cost recovery policy is implemented and the airspace users are made to bear the entire cost of infrastructure development.

En route charges

Over the years, the en route charges policy of the Nigerian air navigation services providers had not been to recover the whole cost. This could be seen from the fact that the $55 unit rate introduced since 1990 is just being raised to $75. For each country that has full recovery policy, the national unit rate of charge is fixed each year.

CONCLUSION

Aside from the implementation of the new CNS/ ATM elements, external challenges will force government and airspace management authorities to review and restructure existing ownership and management. On the demand side, the biggest challenge is accommodating air traffic with existing capacity constraints. Air traffic has been growing steadily due to the globalization of civil aviation industry as well as airline industry deregulation and restructuring. Air traffic forecast for the next ten years or thereabout ranges from 3% to 6%. Many of the existing facilities will need to be rehabilitated and upgraded to meet the demands of air traffic. Given the need for government to reduce fiscal expenditure, Private Sector funding will need to be sought to meet anticipated investment requirements.