AVIATION AND THE ENVIRONMENT
On the one hand there is the constant pressure on economic growth and mobility of companies increasing the demand for transport, on the other hand, negative impacts on the environment that require the finding of a way leading to the possible most respectful and most efficient use of resources and the environment in which we live. These are two sides of the one coin to be paid for progress. We all have merit in it, we all share the responsibility for all the consequences, even those unintended. However, the achievement of such an ambitious and necessary goal, which is the significant reduction of the negative impacts of human activities on the environment, goes beyond the capabilities of an individual, a company or even the government of a single country.
At the beginning of the 90s of the 20th century, an independent coalition of organizations and companies of the aviation industry from around the world was established, bearing the name ATAG (Air Transport Action Group), bringing together approximately 80 members, such as airlines, airports, air navigation service providers, aircraft manufacturers, airline pilots and traffic controller associations. ATAG collects and shares a large database of information and predictions, such as the planning and the development of an environmentally friendly transport infrastructure. Detailed information about the activities of this group can be found on www.atag.org.
AVIATION AND EMISSIONS
At altitudes of about 30,000 to 43,000 feet aircrafts produce gases (carbon dioxide, nitrogen oxides, water vapour - in the form of vapour trails) and particles that contribute to the overall effect of human activities on the greenhouse effect. But the important thing is that these emissions produced by flights at high altitudes, according to current research, do not contribute to ozone depletion. In addition, thanks to modern technology, the production of carbon monoxide, unburned hydrocarbons and smoke almost disappeared. It is worth mentioning that the amount of carbon dioxide emissions produced by air traffic (1992) made up 2% of its total production caused by human activities, in 2050 this ratio could constitute 3% of the total production, compared to approximately five per cent of the expected annual growth in air traffic.
Water vapour is a natural product of the combustion process, as well as carbon dioxide. Serious research has not confirmed the nature and the extent of the impact of water vapour on climate change so far but the consideration is that the water vapour creating vapour trails and sometimes resulting in the forming of cirrus clouds (clouds in the top floor) form a layer in the atmosphere that holds the solar radiation reflected from the surface of the Earth and thereby contributes to the warming process.
Nitrogen oxides are also a by-product of combustion, it being understood that the greater the pressure and temperature inside the combustion engine, the higher their production is. Which of course opens the door for further research and development in the field of aircraft propulsion units. Emissions of nitrogen oxides at lower levels tend to increase the formation of ozone, which has a local effect on air quality. Production of these oxides by aircrafts at high altitudes, on the contrary, have no noticeable effect on the concentration of these oxides in the stratosphere.
Altogether, emissions from air traffic make up a share of 3.5% on the climate change caused by man. The basic prerequisite for dealing with this problem was setting emission limits for aircraft engines, which was the task of ICAO (International Civil Aviation Organization). Today, these limits are defined in Annex No. 16 to the Chicago Convention. There are several ways of how not to exceed these limits and to seek to ensure the possibility of a further reduction of the environmental impact. The use of new technologies should lead to a further reduction in fuel consumption, among other things, through research in the field of propulsion units and aircraft designs. In 5-10 years, the airline industry has ambitions to reduce its share in the total production of nitrogen oxides by as much as 50%. Another way is to improve the infrastructure, supported by the research and implementation of new practices in the field of communications, navigation, ATM systems - allowing for the expected saving of 6-12% of the fuel used for one aircraft / flight.
Then there are the economical and environmentally proactive measures of airlines and their international Association (IATA) trying to free their aircrafts from each unnecessary burden increasing in direct proportion the fuel consumption, to fly in a range of optimum travel speed, to shorten taxiing times, etc. A possible solution is a market-oriented collection of taxes on emissions, a compensation for carbon production and emissions trading. For a better idea about the fuel consumption it can be added that compared to 75% of the total fuel consumption achieved by road transport, the aviation makes up a share of 12% within the whole transport sector.
During the last 30 years there has been approximately a 50% improvement in the use of the ratio of fuel / passenger / km. In the future, the use of alternative fuel types (such as kerosene replaced by hydrogen) is considered, but this also requires new airplane design solutions, finding the possibilities of supplying and storing the new type of fuel. This, however, brings additional safety requirements, the key criterion for the assessment of any alternatives in the aviation industry. At present, there is practically no substitute for kerosene, so the efforts of all involved airline entities focus on its effective use.
The air navigation service providers can participate on the solution of this problem in terms of the currently applied shortening of the time spent by aircraft taxiing on the airport surface with running engines (which can now save more than 300,000 tons of fuel per year in the European area), then by the use of, for this purpose, previously reduced vertical separation minima (another annual saving of approximately 310,000 tons of fuel). By using the concept of flexible airspace, approximately 120,000 tons of fuel per year need not be needlessly burnt in Europe, in sum, therefore, more than 700,000 tons of fuel are saved, the equivalent of 2.3 million tons of carbon dioxide produced.
The most frequently mentioned "by-product" of the significant contribution of air transport to the economic development is the NOISE that has the greatest impact on the residents of municipalities neighbouring the airport. The level of noise pollution depends on the location of municipalities in relation to the used take-off and landing runways, on the aircraft type and of course on the number of movements. There are three ways to deal with noise, where only their joint use can guarantee a truly effective solution of this problem. The first one is sophisticated development planning which would prevent the inhabited parts of villages continually approaching the airports. The second option is to use quieter aircraft, which the carriers try to achieve when renewing their fleets (it is worth mentioning that a conventional passenger aircraft is today by as much as 20 db. quieter in comparison with a similar machine which flew only thirty years ago, and recent research even suggests that during approx. one decade, it will be possible to reduce the noise from the plane by another 10 db. - a sound reduction by 10dB is perceived by human ear as a weakening of the original sound by a half). The third way to achieve noise reduction is the implementation and respecting of noise control measures.
Only this third option is under partial control by the company ANS CR, s. e., which in its activities proceeds solely under the provisions of Air Law No. 49/1997 Coll. When providing air navigation services the management respects all mandatory procedures, working technologies and the structure and use of departure and arrival routes to the airport. These procedures are based on the above Air Law, the essential part of which is the issue of protection zones in terms of limiting noise pollution, set out by the state administration in the field of civil aviation – the Civil Aviation Authority of the Czech Republic. When providing air traffic services, ANS CR, s. e. aims to provide the maximum possible elimination of the negative impact of noise on residents of adjacent municipalities, in any case, there is no violation of statutory limits for noise caused by air transport. For illustration, in the case of Ruzyně Airport this includes the alternate use of the take-off and landing runway 06/24, the maximum traffic limitation on runway 13/31 and the emphasis to be put on noise restrictions for air carriers, especially at night. More information about these procedures can be obtained in the Aviation Information Publication (AIP), in part AD.
Skyway – The EUROCONTROL Magazine – Volume 11, Number 44, Spring 2007
Aviation and the Environment – Material prepared for ATAG by IATA