Mirko Tatalović, D.Sc.Sanja Steiner, D.Sc.Ivan Mišetić, M.Sc.Manuela Košenski, B.Eng.

NEW TECHNOLOGIES AND AIR TRAFFIC SAFETY

Zagreb, 22 March 2004

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INTRODUCTIONThe external challenges that increase the pressure on the efficiency and safety of airline operation

are intensifying and becoming more complex. Various mechanisms of controlling the costs that were used in the eighties are no longer sufficient, and neither are the new management models of optimising the revenues that were used in the nineties of the last century. It is necessary to introduce new elements of increasing the fleet productivity. Efficient harmonisation of the fleet capacities not only at the level of the annual expected industrial standard of occupancy (e.g. aircraft occupancy of 68 per cent), lacks a sufficiently stratified and integral approach to solving the problem of different oscillations in the traffic demand. This does not refer to the need to reduce or increase the fleet capacities, but rather to find the dynamic solution of the optimal mix of the range of different aircraft sizes according to different phenomena regarding peak loads (weekends, tourist season, holidays, etc.).

New technologies of air traffic have to respect the basic factors of sustainable development, especially with regard to the congestion of traffic and infrastructure capacities, replacement of noisy aircraft, reduction of jet engine emissions. Apart from its safety dimension, the future development of technology in air traffic will be predominantly oriented towards increasing the cost-effectiveness of operation.

1. DYNAMIC MANAGEMENT OF FLEET CAPACITIESAdapting the dimensions of the fleet capacities according to peak requirements would obviously

prove to be irrational and counterproductive. Using the dynamic approach, the capacity marketing can be adjusted by modelling the forecast demand and by monitoring over time the determined positive or negative deviation of the interests expressed by the service users (usually at least one week before the planned aircraft departure), thus resulting in higher utilisation rate of the capacities. Two preconditions have to be met here in order to implement the dynamic management of fleet capacities:

the possibility of aircraft replacement on the route network at the adequate transfer point of the hub-and-spoke system;

structure of the fleet which consists of aircraft of various capacities, if possible within the same operative family of aircraft (e.g. A320 family, which consists of A318, A319, A320 and A321).(1)

The assumptions for categorizing the family of aircraft are harmonised integrated systems of size and range of the aircraft, cabin and cockpit configuration, as well as the peak of the designer's philosophy, i.e. operative synergy which allows usage of different types of aircraft of the same family without any additional requirements and costs for the pilot training, maintenance and ground services of aircraft handling.

Crucial requirements regarding aircraft replacement are thus met and the exchange can be done very flexibly in harmony with the current situation on the route network, without adding any frustrations for the flight schedule planners and the airline operative centre. However, additional problems can be caused by a possible need for a bigger cabin crew, i.e. by specific requirements of cargo transport that do not have to correlate with the decline or increase in the traffic demand, but can have completely opposing tendencies. Of course, there may appear other unplanned difficulties for the reservation agents, occupancy control, etc. However, the technological and operative harmonisation of dynamic fleet capacity management certainly contributes in a much more positive manner to the expected results than the mentioned possible problems and deviations.

The hypothetical example of the network of the European airports with the adequate fleet of eight units of various types from A318 (107 seats) over A319 to A320 (150 seats), which use the same transfer airport for the change of fleet capacities, by applying the known “Monte Carlo” mathematical method of operative research, direct annual savings of US$ 700,000 were determined, and the total saving including other induced and indirect savings amounted to as much as US$ 1,600,000.(2)

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2. OPTIMISATION OF THE ROUTE NETWORKThe issue of airline route network optimisation can be valorised differently, since its starting

positions do not necessarily have to be identical to the requirements and responsibilities of the civil aviation administration which represents wider social interests including also the government aircraft regulations, the availability of air routes and airports capacities. The creation of the so-called "hub-and-spoke" system parallel with the process of liberalisation and deregulation of the air traffic in the U.S.A. has influenced the rationalisation of the network and transition from the linear route structure to the route structure via central transfer airport (hub), which is discussed further in the text.

Since in practice the direct and indirect connections are usually combined, the idealised schematic "hub & spoke" presentation leads to the conclusion that the introduction of one central inter-landing in cross-connecting combinations (connecting the pairs of cities) has significantly rationalised the route network. It is obvious and can be mathematically proven that the number of connections necessary to serve all the nodes in the network, either directly or indirectly, does not increase linearly with the increase of adding new nodes, i.e. airports served by an airline.

Number of service nodes Number of direct serving Number of indirect serving

3 3 24 6 35 10 46 15 57 21 6

Further evolution and improvement of the route network efficiency follows the increasingly intense growth of traffic effects and the appearance of alliances. A model of multiplicative hub system has appeared and usually two big transfer centres (hubs) interconnected directly with the possibility of serving numerous satellite towns - airports.

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Scheme 2: “Hub & Spoke” route structureScheme 1: Linear route structure

AA BB CC

DDHHGG

II EE FF

AA

BB

CC

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II HH

The appearance of global alliances has resulted in the doubling of the presented effects of the multiplicative hub system in two different regional units (e.g. Europe and the USA in combinations Lufthansa and United, British + American, KLM + Northwest, Air France + Delta, etc.).

Of course, a great number of airlines in the world have neither objective need nor conditions to implement the presented models in practice due to the restricted size of the market and the serving frequency. Even in the U.S.A. where a dominant number of especially big airlines uses in practice the “hub” system there is an exception from the rules e.g. in case of SOUTHWEST which avoids in this way the negative implications of congestion and saturation of airport capacities. (3) But this is the general rule of the so-called “low cost” carriers who build the route network primarily on the domination of “point to point” passengers compared to transfer or interline passengers. There is an increasing development of interconnected pairs of cities (cross-connecting flights), and intensifying of the number of aircraft that fit into the arrival – departure waves (bank, wave) within a certain reasonable time interval. A good example is the optimisation of the route network at the Chicago O’Hare airport resulting from the following assumptions:(4)

peak wave of 50 aircraft;

time interval of arrivals – 1.5 aircraft per minute;

time interval of departures – 7 aircraft every 5 minutes.

Based on the mentioned starting parameters it follows that the time interval necessary for the transfer of passengers amounts to 34 minutes in arrival, 35 minutes in departure and 30 minutes for the ground transfer, which means a total of 99 minutes. Obviously, from the position of increasing productivity it is important to insure maximally short time of the overall passenger transfer.

In the optimisation process of the route network there are of course many route restrictions and potential threats. These are first of all airport slots, limited number of departure/arrival gates, ground transfer, limited capacities of runways, manoeuvring areas, restrictions in the security checks of passengers and baggage, restrictions at customs control points, restrictions due to adverse weather conditions (fog, snow, wind, etc.). The mentioned restrictions have made certain transfer airports to “stretch” and reduce the excessive transport demand by the logic of continuous flows, filling the gaps in daily traffic low tides. It is interesting to note that the US mega carriers (the MAJORS group) have already reached the level of 14 daily waves at their domicile transfer airports (hubs), whereas the leading European air-carriers have not yet exceeded the two-digit figure of daily waves.(5)

There are certain rules of consistency in creating the flight schedule, which contribute to its easier monitoring, and also more successful realisation. There are also the following practical instructions:

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Scheme 3: Multiplicative hub route structure

AA

BB

II

FF

HH11

CC

HH2 2

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EE

GG

LLKK

set the identical times of arrivals and departures during the week;

plan the weekly servicing with the same type of aircraft excluding the day of extremely low demand;

use always the same flight number in the considered week;

keep the same flight number during the entire flight schedule season (summer/winter);

use always the same daily departure / arrival gates;

leave the big transfer markets as close to each other in order to facilitate ground transfer.

In practice the appearance of global world alliances as a rule facilitates and speeds up the transfer flows of the alliance partners compared to airlines of the competitive alliance.

The mentioned flows within the complex of the transfer airport by sequential approach are additionally regulated according to the character (in arrival, in departure), aircraft type (long range jet, wide-body jet, narrow-body jet, turbo-prop). Using the mathematical methods of sequential algorithm of LIFO type (last in – first out) for the arrival complex, unlike FILO (first in - last out) especially in case of intercontinental arrivals due to the complexity of procedure and minimising the possibilities of delays for the ongoing flight. Apart for themselves, the domicile airlines use the same FILO principle also for the flights of their code-share partners.

It should be eventually concluded that the process of optimising the route network is a challenging and complex task which includes also additional requirements of optimising the fleet, forecasting traffic flows, revenues management, statistic processing of start and end destinations, highly trained and educated personnel, etc. Also, the security dimension of the problem is important, which does not put up with concessions.

3. CONGESTION OF TRAFFIC CORRIDORS AND AIRPORT CAPACITIESThe difficulties in regular safe and high-quality operation of air traffic in the world are growing,

causing additional extra costs. The Federal Aviation Administration (FAA) in the U.S.A. found that the average delay per flight in the year 1989 in the U.S.A. amounted to 16.6 minutes, which represents over 1.74 million hours of delays annually, primarily due to the saturation of air routes.

The Association of European Airlines – AEA has estimated that, due to the limited capacities and bottlenecks, the inefficient European air traffic control realised an expenditure of over US$ 4 billion in the year 1988.

In Europe the situation is extremely bad since, according to the AEA annual report the air traffic control had 49 different ATC centres, 31 national systems, 18 hardware suppliers, 22 operative systems and 30 programming languages.(6)

Furthermore, the distribution of the cruising altitude according to the EUROCONTROL data indicates that there is maximum demand for the flight level from 33,000-35,000 feet referring to almost one third of the total number of flights.

Therefore new solutions have been proposed, in which the current limit of minimal vertical separation of 1000 ft would be moved from FL 290 to FL 410, and after that, up to FL 450, it would be defined at the level of 2000 ft.(7) The so-called RVSM project (Reduced Vertical Separation Minima) was introduced in April 2001 between Great Britain and Ireland, and the introduction of the system is to follow in the North Atlantic and within Europe, which could increase the aircraft throughput capacity by as much as 30 per cent by the year 2007. (8) Eurocontrol introduced RVSM in Europe for a total of 41 European countries on 24 January 2002, representing 20 per cent increase in capacities of upper airspace. Due to reduced delays, fuel saving and positive influence on environmental protection, this might result in Euros 3.9 billion of reduced costs.

Similar to this is the project of polar route which significantly reduces the overflight time between the destinations of North America and Asia, whereas the introduction of FL290-FL390 for the U.S.A. is planned in the year 2004.(9)

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The time savings between single attractive city pairs (cross-connecting flights) is presented further in the text:(10)

ATLANTA – SEOUL 124 min

BOSTON – HONG KONG 138 min

LOS ANGELES – BANGKOK 142 min

NEW YORK – SINGAPORE 209 min

VANCOUVER – HONG KONG 125 min

Whereas at the end of the eighties there were about 100 nodes in Europe, in the year 2000 there were already over 450 nodes and they had an excess of 20 aircraft per hour.(11)

By the year 2010 the magnitude of the global investments required by the airport infrastructure and the air traffic control equipment will have risen to the amount of US$ 350 billion (12) where 75-80 per cent of the mentioned investment requirements refers to the region of N. America, Europe and the Asia-Pacific region.(13)

According to the research of the SRI institute, in the year 2010, the list of major European airports that will need significant expansion of infrastructure capacities comprises 14 (Athens, Copenhagen, Düsseldorf, Frankfurt, Geneva, Hamburg, London (LGW), London (LHR), Madrid, Manchester, Milan (LIN), Munich, Paris (ORL), Zurich).(14)

The experts from the Institute have quantified the annual European losses due to the failure to undertake timely investment activities and consequent creation of traffic jams and congestion to the amount of almost US$ 10 billion annually.(15)

The situation is similar also in other parts of the world. By the year 2010, US$ 14 billion will have been invested in the U.S.A. in the expansion and modernisation of the airport infrastructure at Dallas, Phoenix, Denver, Charlotte, Miami, Houston, Orlando, Minneapolis, Washington, Dulles, Seattle, St Louis, Atlanta and Cincinnati.(16)

In Asia the biggest infrastructure modifications are planned in Singapore, Kuala Lumpur, Suwannabhuma (Thailand), Guangzhon (China), Haneda and Narita (Japan), etc.

4. PROBLEMS OF NOISY AIRCRAFT REPLACEMENTReacting positively to the requirements of improving the conditions of environmental protection,

ICAO has determined the liability of gradual noise reduction by 10 decibels (EfDBPN).

In this respect it has determined, classified and issued certificates on the levels of noise caused by single types of subsonic jet engines. In simple terms, the aircraft are divided into three categories:

1. Aircraft that comply with the required level of noise – "silent" aircraft – Chapter 3 Annex 16,

2. Aircraft that comply partly with the required level of noise, and need to be fitted with hushkits or phased out of service - Chapter 2 Annex 16,

3. Inadequate aircraft that cannot obtain the certificate of airworthiness – NNC (Non Noise Certificated).

Significant reduction of aircraft noise regarding the first generation of subsonic jet aircraft has been realised owing to the wider implementation of the advanced acoustic technology. The average improvement of the level of noise at three certification reference points (takeoff, lateral line, and approach) amounted to 9 EPNdB for long-range four-engine aircraft, 7 EPNdB for three-engine mid-range aircraft, and 15 EPNdB for twin-engine short to mid-range aircraft.(17)

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FAA has decided to solve the problem of aircraft noise level in the U.S.A. with reference to Chapter 2, according to two different scenarios:

1. For airlines whose entire fleet consists of Chapter 2 aircraft, Annex 16 according to the following schedule:(18)

25 per cent of aircraft by the end of 1994;

50 per cent of aircraft by the end of 1996;

75 per cent of aircraft by the end of 1998;

100 per cent of aircraft by the end of 1999.

2. For airlines with fleets consisting only partly of Chapter 2 aircraft, Annex 16:

minimum 55 per cent of aircraft by the end of 1994;

minimum 65 per cent of aircraft by the end of 1996;

minimum 75 per cent of aircraft by the end of 1998;

100 per cent of aircraft by the end of 1999.

However, 15 per cent of the mentioned fleet category are permitted to stay until the end of 2003 provided technological process of fitting the engines with hushkits is performed, and further import of such aircraft in the U.S.A. is banned “but maximally for 10 per cent of the adequately aged fleet group”.

The start in regulating noise in the mentioned manner affected the airlines in non-restrictive regions, especially Africa, South America and Eastern Europe, both due to the limited investment possibilities of purchasing new, more advanced fleet, and by extremely high noise penalisation.(19)

According to the ICAO data, at the beginning of the year 1991, in the world, out of a total (excluding the Russian aircraft in domestic traffic) of ca 9000 jet aircraft, the share of the problematical, i.e. "Chapter 2" aircraft amounted to 48 per cent of the entire fleet. Based on the consultations with single ICAO member countries, some regions and countries, e.g. the ECAC countries, USA, Australia, Japan and New Zealand immediately announced operative restrictions for aircraft that do not comply with the "Chapter 3" conditions.

Operative restrictions started on 1 April 1995, and the final deadline for "silencing" the noisy aircraft was 1 April 2002, determining the guaranteed life-cycle of aircraft up to 25 years for the duration of the mentioned time interval.

It was found that out of 4749 Chapter 2 aircraft, 3425 refer to aircraft in the mentioned restrictive areas, and 1324 are aircraft in other regions which did not accept such stringent conditions.(20)

It is estimated that the whole replacement of narrow-body aircraft including the engine hushkitting procedures amounted to about US$ 4-5 billion.

Respecting the basic components of sustainable development (economic, environmental and social), regarding future generations of aircraft engines the manufacturers will have to comply with the following requirements by the year 2010:

reduction of fuel consumption by about 20 per cent;

reduction of direct operative costs by about 3 per cent;

reduction of noise level by 10 dB;

reduction of NOx emissions by 85 per cent.(21)

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5. ESTIMATE OF EFFECTS OF CONTROLLING AIR POLLUTION CAUSED BY JET ENGINE EMISSIONS

Similarly to the previously described problems of noise, the technology has been continuously developing in the attempt to reduce maximally the jet engine exhaust emissions. The least expensive of the performed measures is to minimise the time of engines running on the ground such as e.g. delayed or last-minute starting of the engine, during the pre-takeoff waiting on the taxi- and runways for clearance. Similarly, early shutdown of the engines after landing, although it should be noted that the described application of this technology at the same time increases the level of noise due to the fact that this requires usage of more power and greater engine thrust.

Based on the very intensive research and published results by the Environmental Task Force ETF formed by IATA it has been undoubtedly determined that the range of air traffic impacts on the environment includes: (22)

air traffic energy consumption amounts to 5 per cent of the world oil consumption, and 12 per cent of oil reserves of the total world transport system;

jet aircraft emit 2-3 per cent of global world emissions of nitrogen oxide NOx and carbon dioxide CO2;

jet engines with the mentioned CO2emissions account for as little as 1 per cent of the global warming phenomenon;

air traffic uses as little as 8 per cent of useful land compared to the areas necessary for railway traffic, i.e. 1 per cent compared to the needs of road traffic;

regarding noise, one should keep in mind that aircraft are not the only noise generators at airports.

Besides all the mentioned, it has been determined that aircraft of the nineties are many times more efficient compared to the obsolete types of the seventies regarding:

more rational energy consumption, of 3-4 per cent on the average annually;

85 per cent less unburned carbon dioxide;

70 per cent less carbon monoxide emissions;

reducing the number of noise endangered population to only 5 per cent compared to the situation in the seventies.(23)

Air pollution caused by regular needs for engine testing and maintenance can be controlled by using test stations equipped with after-burn chambers and catalytic converters.(24)

Actually, the air pollutants are divided into five groups:(25)

tiny particles;

carbon monoxide;

photochemical oxidants;

nitrogen oxidants;

sulphur oxide.

Tiny particles are solid or liquid substances dispersed in air and smaller than 500 microns. The average annual concentration of tiny particles of 75 microns/m3 can have negative impact on the people's health identical to the maximum daily level of 260 microns/m3 which occurs once a year.(26)

Apart from the need to modify ground operations and airport infrastructure capacities, and due to the mentioned dimensions of significant increase in the air traffic volume regarding the projection of the future development, the jet engine modifications obviously also need to be taken into account. Especially "dangerous" is the nitrogen oxide (NOx) which contributes to the phenomena of ozone

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holes in the upper layers of the atmosphere and is related to acid rains and smog in the lower atmospheric layers.

Although it is estimated that, compared to other pollutants, the share of NO x is hardly 1 per cent (road traffic almost 50 per cent),(27) the Boeing Company, as well as other aircraft manufacturers are continuously emphasising the need to reduce fuel consumption and to reduce the engine exhaust emissions. Thus, e.g. the proposed GE90 engine of the B-777 implements the new technology of energy-efficient engines (E3), which can reduce the NOx emission by 35 per cent compared to the previous engine generation.

Considering all the mentioned factors and the applied methodology of long-term projection of air traffic development in the world the authors of which are the most relevant subjects and have to be as objective as possible in their forecasts, it may be concluded that the implementation of the ever stricter standards of sustainable development and environmental preservation will partly affect the slowed dynamics of air transport growth, thus including the level of realised productivity. However, on the other hand, their implementation will have positive effects on the level of air traffic safety.

6. FUTURE DEVELOPMENT OF ADVANCED TECHNOLOGIES IN AIR TRAFFIC

From its start, the aviation has been in constant dynamic tension with marked and continuous technical and technological improvements and progressive changes in trying to realise the increase in capacities, speed, range, comfort and safety of air transport. There is a long way yet to go until all the possibilities of further improvement are used, especially regarding the improvement of productivity and business efficiency.

The latest research funded by the NASA (National Aeronautics and Space Administration) and FAA indicate the technical, technological and economic acceptability and justification of introducing the tilt-rotor into commercial exploitation. The tilt-rotor has originated from the military program, but the achievements regarding the increase in productivity of air transport are significantly limited.(28)

The basic idea of the mentioned technical and technological improvements is the modernisation and improvement of efficiency, throughput capacity and safety in air traffic flows in the world.

In spite of intensive research in technology of aircraft engine manufacturing, as the latest evolution phase in the series of classical engines, it is considered that the turbo-jet aircraft and engine may be swept out of exploitation only at the moment when one of the developing and qualitatively new concepts of electro-dynamic theory of matter e.g. ionic or photon engine, plasma engine, etc. make the technical and technological turn and satisfy the conditions of economic exploitation.(29)

A similar futuristic and for the moment commercially and regarding exploitation unreachable dimension seems to belong to the announcements of revolutionising the cargo traffic involving the introduction of dirigibles of the capacity of about 500 t at a speed of about 150 km/h.

Consequently, by the year 2020 and later, no major revolutionary changes in the technologies of manufacture and usage of commercial aircraft can be envisaged. New electronics, new engines, new materials and other innovations result primarily from the reduction of unit operative costs per passenger seat, i.e. passenger kilometre, first of all by maximal rationalisation and reduction of fuel consumption. According to the forecasts made by the Airbus experts, the average annual rate growth of the flight distance by the year 2019 as compared to 1999 will amount to as little as 0.26 per cent, speed block 0.07 per cent, annual utilisation of aircraft 0.32 per cent, and passenger load factor PLF only by 0.22 per cent, i.e. 3.2 points.(30)

Also the changes in technology are envisaged regarding the usage of classical fuels, i.e. kerosene that in new supersonic aircraft could be replaced by natural gas, liquefied oxygen or liquefied hydrogen. However, the airline productivity in the world will increase on the whole by a very moderate growth dynamics.

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7. NEW TECHNOLOGICAL AND COMMUNICATION REQUIREMENTS IN AIR TRAFFIC

New technological requirements of aircraft design are increasing daily, but could be basically reduced to several main assumptions:(31)

reduction of the frontal drag of the supporting structure;

increase in aircraft maximum takeoff weight;

improvement of flight performances;

increase in fuel capacity (increased flight range);

reduction of supporting structure weight;

improvements in engine design.

Every of the mentioned activities hides a whole number of subsystems which have to be enhanced. In optimally satisfying the mentioned development requirements, a well-planned and efficient communication system is necessary for the development co-ordination, once known as FANS (Future Air Navigation System), and recently the so-called CNS-ATM system (Communications, Navigations, Surveillance – Air Traffic Management).

One of the significant preconditions for implementing the World Area Forecast System, WAFS, is precisely a high-quality communication system that will provide timely, accurate and full information on the meteorological and other preparation activities for safe flying. By completing the satellite distribution by installing the Intelsat satellite in the Indian Ocean with the base in London, the so-called SADIS, entire world coverage was realised together with the already earlier installed WAFS centre in Washington, which covered by satellite network a wider area of the Atlantic and the Pacific.(32) The system enables the implementation of the digital binary coordinate codes and graphic forms for stressed weather situations (the co-called SIGWX – Significant Weather) wind and temperature changes at different altitudes, and alphanumeric operative meteorological messages.(33)

The mentioned communication improvements are extremely important, since without integral and good information, which is contained in the mentioned reports, errors would be possible as well as significant deviations in the 24-hour or 36-hour forecasts, where the error in estimated value of the upper level wind is sometimes almost doubled.(34)

8. APPLICATION OF AIRCRAFT SATELLITE COMMUNICATION AND TECHNOLOGY

Considering the present technical restrictions in the existing communication, aero-navigation and surveillance systems, the FANS(Future Air Navigation System) Committee was formed in 1988 within the ICAO, with the aim of organising and preparing for implementation the future global concept based on the integration of two latest world satellite navigation systems – the Russian GLONASS (Global Navigation Satellite System) and the US GPS (Global Positioning System) forming thus a unique GNSS (Global Navigation Satellite System).

The satellite navigation revolution started in 1978 with the GPS system that the USA offered for civil usage at the end of 1983, and the whole constellation was completed in 1994. This system consists of the satellites, ground control instruments and the users. The air segment consists of 21 orbiting satellites and three active parts. The satellites follow the orbit in an interval of 11 hours 57 minutes at the altitude of 20,187 km. The satellite constellation is organised in six orbital planes with the inclination of 55 towards the equator, allowing 99 per cent of tracking and usage. The GLONASS system has been set in a similar manner and the time interval is 11 hours 15 minutes at the altitude of 19,100 km, and the satellite constellation is organised in 3 orbital planes, each consisting of 8 satellites with orbits that have an inclination of 64.8 to the equator. With additional 24 satellites on both sides it realises a 100 per cent coverage, even in case of breakdown of 3 GPS and 3 GLONASS satellites.(35)

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The schedule of realising satellite communication, navigation and surveillance plans the development tests, demonstrations and partial implementation of the new system, after which FANS system would run parallel with the existing navigation systems until 2005, and by the year 2015 the current classical systems would be gradually abandoned, and in 2015 only FANS operations and activities would start to be used..(36)

The analyses done by the experts and scientists speak in favour of the new CNS/ATM system because of its many advantages, such as e.g.: (37)

increase in the level of safety and quality of aircraft operations;

implementation of the system can be achieved by different institutional arrangements;

state sovereignty and FIR borders (borders of the regional air traffic controls) will not affect the implementation of the new system;

the implementation will be progressive and supervised by the interested individual countries;

ICAO and professional regional organisations can offer professional assistance and support to countries that will need or require it.

Consequently, and having information about the estimates and attitudes of professionals, scientists and operators, IFALPA(38) have assessed that the introduction of satellite technology is the biggest and most revolutionary move in the civil aviation since the beginning of jet engine usage. The CNS system evolution obviously has no alternatives and has caught a sound rhythm of realisation, thus making it necessary to mention the basic elements of the system. As implied by the word CNS system itself, it refers to three subsystems:

Aircraft communication C

Aircraft navigation N

Control and surveillance S

The conclusion of the performed analyses and research is that the elements of introducing the CNS system are in close connection with the trends of productivity and safety of air transport. The analyses show safe and unambiguous advantage of implementing the new system of satellite technology. The US FAA (Federal Aviation Administration), namely, have analysed the overall effects of implementing the satellite CNS system and have confirmed the definite advantages resulting from:(39)

favourable routes;

favourable flight altitudes;

reduction in delays;

regarding wind more efficient routes;

reduced fuel stocks;

more dynamic rerouting;

fast response to variable requirements, etc.

Thus, owing to the still sound development rates of air traffic which are forecast in the near and far perspective, new technological and communication requirements are becoming more complex, detailed and more precise. This has resulted in the need to elaborate a model of implementing the latest aircraft satellite communications and technologies known under the title CNS technology. Its three basic components – communication, navigation and surveillance will significantly improve the essential elements of efficiency and safety of air traffic flows. The experts have estimated that the implementation of the ATM system will start the greatest changes in the field of the so-called conflict management.(40)

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9. AIR TRAFFIC SAFETY INDICATORS IN THE WORLDThe analysis of air traffic safety in the world distinguishes, according to the causes, two basic

categories of aircraft accidents:

- accidents involving fatalities caused by illegal violation of air traffic safety (hijacking, etc.);

- accidents caused by other factors (technical failure, human factor, etc.)

This section refers to the term 'safety', i.e. operative procedures in air traffic process which result in endangering the safety of this process due to carelessness, ignorance or technical failure.

The table presents the classification of aircraft accidents according to the causes. It contains 10 basic causes for the period between 1988 and 1993.

Table 1: Classification of aircraft accidents according to causes

Cause Number of accidents

Number of fatalities

CFIT (Controlled Flight into Terrain) 28 1883

Loss of control (aircraft) 10 460

Loss of control (crew) 14 357

Design 4 278

Mid-air collision 1 157

Ice/snow 4 134

Fuel depletion 5 107

Loss of control (weather) 2 79

Missed runway 3 43

Other 5 15Source: L. Taylor: Air Travel: How safe is it?, Blackwell Science Ltd, Oxford, 1997.

The analysis of aircraft accidents indicates the distribution of flight operation, with the approach phase being the most critical. The presentation of the distribution of aircraft accidents according to flight phases leads to the conclusion that the highest incidence (about 70 per cent) of accidents is in the start-end operations which account for 6 per cent of the overall flight operation time.

Table 2: Analysis of aircraft accidents according to flight phases

Flight phase Share in accidents (%) Share in flight time (%)

Boarding/disembarking, taxiing

1.9 0

Takeoff 14.2 1

Initial climb 10.1 1

Climb 6.7 14

Cruising 4.5 57

Descent 6.9 11

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Initial approach 11.4 12

Final approach 24.3 3

Landing 20.1 1Source: Ibidem, Table 1

According to the ICAO data, in 2002 there were 14 fatal aircraft accidents in the scheduled air traffic with 791 killed persons, as compared to 13 accidents with 577 killed in 2001.

The number of killed passengers per 100 mill. of realised passenger kilometres increased from 0.020 in 2001 to 0.025 in 2002.

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

0.080

0.090

0.100

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

Source: ICAO Journal, Annual Review of Civil Aviation, Vol. 58, No. 6, 2003, p. 38

The graphic presentation shows that there is no rule in the incidence of fatal accidents, and that the oscillations are big and unpredictable. However, on the whole, it may be concluded that, considering the increase in the traffic volume, change in exploitation performances and the fleet age structure, the number of accidents is on a relative and sometimes even absolute decline.

All that has been mentioned confirms the thesis that the safety area in air traffic is studied in great detail and very studiously, and it is being improved, including the human factor.

The air traffic safety can be positively affected by the pilot training and the implementation of safety equipment. The prevention is oriented to the improvement of airport instruments for approach guidance of aircraft, air carriers are advised to use flight data registers, and to use the systems that warn of dangerous approaching the terrain – GPWS (Ground Proximity Warning Systems) etc.

This is the only way in which better results can be achieved.

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10.CONCLUSIONSNew air traffic technologies are based on the optimal dimensioning of the sizes and methods of

fleet capacity management as precondition for the optimisation of the route network that should efficiently respond to the problems of the congestion of traffic corridors and airport capacities.

The improvement and modernisation of technology imposes increasingly stringent conditions for the replacement of noisy aircraft and the control of air pollution resulting from jet engine emissions.

However, the future development of advanced technology regarding the possible wider implementation of the tilt rotor, new technological and communication requirements, and the implementation of the aircraft satellite communication and technology, will not improve significantly the productivity of air transport. The forecasts by the experts and scientists are very moderate and range within the average annual growth rates of only 0.07 per cent (block hours), PLF of 0.22 per cent, flight distance 0.26 per cent, and WLF of 0.32 per cent.

LITERATURE AND REFERENCES1. More than 40 airlines in the world use at least two models of the mentioned A320 family of

aircraft.

2. CLARK, P.: Dynamic Fleet Management, Handbook of Airline Economics, New York, 2002, p. 115-116.

3. BUTTON, K.: Airline Network Economics, Handbook of Airline Economics, New York, 2002, p. 32.

4. BERDY, P.: Developing Effective Route Networks, Handbook of Airline Economics, New York, 2002., p. 121.

5. Ibidem, p. 123.

6. AEA: Yearbook 1997, Bruxelles, 1997, p. 24.

7. HEIJL, M.: More Cruising Levels Expected at Higher Altitudes, ICAO Journal 1/90, Montreal, 1990,

8. Rolls-Royce: op. cit., p. 23.

9. ITA Press broj 400, Paris, 02/2002, p. 11.

10. AVIONICS MAGAZINE 04/2002, p. 26.

11. IATA REVIEW: Europen Congestion – the Way Out 1/90, Geneva, 1990, p. 5

12. ICAO Circular 236-AT/95: Investment Requirements for Aircraft Fleets and for Airport and Route Facility Infrastructure to the Year 2010., Montreal, 1995, p. 1.

13. Ibidem.

14. SRI Intl: A European Planning Strategy for Air Traffic to the Year 2010, Menlo Park, 1990., p. ES-2.

15. SRI Intl: op. cit. p. ES-2.

16. Rolls Royce: op. cit. p. 22.

17. ICAO Circular 157-AN/101: Assessment of Technological Progress Made in Reduction of Noise from Subsonic and Supersonic Jet Aeroplanes, Montreal, 1981, p. 41.

18. IATA: Environmental Review 1996, Geneva, p. 76. 77.

19. During years 1995 and 1996 the noise penalisation for Croatia Airlines aircraft B737-200 was more than US$ 1 mill.

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20. WICKRAMA, K.K.: ICAO Study Estimates Economic Impact of Newly Adopted Noise Resolution, ICAO Journal, Nov/1990, Montreal, 1990, p. 9.

21. ICAO: Aviation Industry Development, 2000, SPL London, p. 72.

22. IATA-ETF: Air Transport and the Environment, Geneva, 1994, p. 4.

23. Ibidem: p. 4-5.

24. ICAO: Airport Planning Manual, Doc 9184, Part 2 Land Use and Environmental Control, Montreal, 1985, p. 2-7.

25. ASHFORD, N-WRIGHT, P.H.: Airport Engineering, New York, 1984, p. 416.

26. Ibidem, p. 417.

27. Commercial Airplane Group of Boeing: op. cit. p. 47.

28. Cfr. supra chapter 5.5.4.

29. NOVAKOVIĆ, S. et al.: Razvoj saobraćaja Jugoslavije do 2000. godine, knjiga I, Beograd, 1981., p. 253.

30. Airbus: op. cit., p. 15.

31. OUEY, J.: Application of new technologies to airframe, systems and engines improve Trijet’s performance, ICAO Journal 1-2/96, Montreal, 1996, p. 7.

32. DALTON, F.: The satellite distribution system provides WAFS products issued by WAFC London to users in an area stretching from the eastern Atlantic to western Japan and Western Australia, ICAO Journal 10/95, Montreal, 1995, pp. 4-5.

33. Cfr. CERNAVA, S.: WATS is on threshold of final phase of implementation, ICAO Journal 10/95, Montreal, 1995, pp. 4-5.

34. Cfr. TURPEINEN, O.M.: Provisions governing air reporting updated by recent amendment to ICAO Annex 3, ICAO Journal 10/95, Montreal, 1995, pp. 12-13.

35. Cfr. HARTMAN, R.: Combined Satellite Navigation Systems Could Lead to More Reliable and More Precise Air Navigation, ICAO Journal, 3/91, Montreal, 1991, pp. 9-12.

36. OSTIGUY, N.: Potential Impact of FANS Far-Reaching and Positive, ICAO Journal 12/91, Montreal,

37. Ibidem: p. 7.

38. IFALPA (The International Federation of Airline Pilots Association), ICAO Journal 12/91, p. 19.

39. DONOHUE, G.: Technologically advanced and integrated ATC system is on our future, ICAO Journal 1-2/96, Montreal, 1996, p. 6.

40. HOWEL, J.: Ground breaking initiative in spotlight at pivotal air navigation conference, ICAO Jurnal 5/2003, p. 9.

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