From the first flight of Wright brothers(1903) to the world’s first airline DELAG, DeutscheLuftschiffahrts-Aktiengesellschaft I(1909), from just one airline to over 5000 airlines and from just one plane to 23,600 passenger planes the aviation industry has come a long way. Airlines transported a total of 4.3 billion passengers in 2018 as of InternationalCivil Aviation Organization (ICAO) and these numbers tend to increase at considerable rates. The enormous economic and social impact of the aviation industry has led to radical changes in the way people travel.
The convenience brought in travel to far-flung places is substantial and the employment generation is tremendous. In India the commendable increase in a number of airports is driving the growth of civil aviation connectivity and infrastructure. Flying has been made accessible and affordable more than ever before. Passengers carried by domestic airlines during Jan-Dec 2018 were 1389.76 lakhs as against 1171.76 lakhs during the corresponding period of previous year thereby regis-tering a growth of 18.60% (DGCA). Thus the aviation industry is growing at a very fast pace in many developing countries like India.
Finally, this brings us to a natural question, ‘Is the Aviation Industry damaging our environment?’
Aviation is basically a fossil fuel industry, one which guzzles an eye-watering 5 million barrels of oil on a daily basis. Burning that fuel currently contributes around 2% of all human-induced carbon dioxide. The second problem is that many of the other sectors have a greener alternative (solar power), there is currently no way to fly 8 million people every day without burning lots of dirty kerosene.
Aircraft are becoming more fuel-efficient, but not fast enough to offset the huge demand in growth. Electric planes remain decades away, weighed down by batteries that can’t deliver nearly as much power density as jet fuel. Several studies have found individuals to be quite unaware of how their own flying behaviour contributes to global climate change. Research into airline websites shows little or no mention of environmental impact. Green NGO’s are typically quiet on this issue, perhaps being reluctant to “preach” their members to fly less, and concerned over accusations of hypocrisy as their own workers fly around the world to conferences. The processing and transportation of the aviation fuel, and therefore the manufacture and maintenance of planes, airports and support vehicles all produce additional greenhouse gases.1
The noise originates from three main sources: Engine and other mechanical noise (gear-box and transmission) Aerodynamic noise (shear layers and sonic speeds) CombustionnoiseThe majority of engine noise is due to jet noise—although high bypass-ratio turbofans do have considerable fan noise. The high-speed jet departure from rear of the engine has an inherent shear layer instability and rolls up into ring vortices. This later breaks down into turbulence. The SPL (Sound Pressure Level measured in decibels) associated with engine noise is proportional to the jet speed (to a high power). Therefore, even modest reductions in exhaust velocity will produce a large reduction in jet noise.The Federal Aviation Administration (FAA) regulates the maximum noise level that individual civil aircraft can emit through requiring aircraft to meet certain noise certification standards. The FAA (Federal Aviation Administration) says that a maximum day-night average sound level of 65 dB is incompatible with residential communities. Communities in affected areas may be eligible for alleviation such as soundproofing. On newer engines, noise-reducing chevrons further reduce the engine’s noise, while on older engines the user of hush kits are used to help mitigate their excessive noise.
What’s an ’aviation multiplier’?The impact of planes on the climate is complicated and not perfectly understood. TheCO2 emissions are straightforward enough, but plane engines also generate a host of other ‘outputs’, including nitrous oxide, water vapour and soot. At flying altitudes in the upper troposphere and lower stratosphere, these outputs produce a range of climatic effects, multiplying the plane’s environmental impact. For example, nitrous oxide causes the formation of ozone — a greenhouse gas that warms the local climate — butat the same time undergoes reactions which destroy methane, thereby removing another greenhouse gas from the atmosphere. Even more complicated is the impact of soot and water vapour, which together can cause contrails (vapour trails) and in cold air can lead to the formation of cirrus clouds. The science surrounding this topic is not yet rock-solid, but researchers believe that contrails add to the greenhouse effect – especially at night, when their tendency to stop heat escaping from the Earth isn’t offset by their tendency to reflect incoming sunlight. Today, most experts favour an aviation ‘multiplier’ of around two. In other words, they believe that the total impact of a plane is approximately twice as high as its CO2emissions. The exact multiplier, however, will always depend on the individual plane, the local climate and the time of day.
Political leaders are unwilling to point the finger at passenger-voters. How many politicians facing a potential election would vote to finish low-cost air travel, none. Aviation is a golden goose for politicians. Aviation, together with shipping, was given special standing and excluded from the Kyoto and Paris climate change agreements. The industry was tasked to come up with its own solutions instead. The International Civil Aviation Organisation (ICAO), finally addressed aviation emissions in 2016, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). Under CORSIA, countries airlines are given allowances to emit carbon, and if they exceed their allowances then they should tradeoff the offset from other sectors. Yet this plan is not nearly radical enough. Offsetting processes may divert the focus from reducing emissions to trading on emissions. CORSIA has also not stated any upper limit to the aviation-related emissions that may be produced by an airline operator ora country. Emissions from domestic air travel are not included in CORSIA. India and Russia are yet to join CORSIA. India has four of the five carbon-neutral airports in the theAsia-Pacific region.
A number of technologies designed to reduce the environmental impact of flying have been researched, tested and implemented. However, compared with greener cars, where the technologies are proved and the carbon saving huge, the potential for eco-friendly flying looks rather limited. There will be some further gains in engine efficiency over the coming decades, and larger planes with more seats will allow slightly lower emissions per passenger. But there is nothing in the pipeline with the transformative potential of the electric car. The problem is that electric motors can’t produce enough power to get a plane off the ground, so the only alternative to regular kerosene-based aviation fuels is special kinds of biofuels. These aren’t an ideal solution, since biofuels can be environmentally problematic in themselves, and anyhow it would take a huge chunk of the world’s arable land to grow enough crops to fuel all the world’s planes. (A back-of-the-envelope calculation suggests it might require as much as a fifth of all cropland.)For anyone concerned about their contribution to global warming, cutting back on air travel is an obvious goal. This might mean giving up flying altogether or it might mean taking fewer flights and picking destinations that are closer to home. It’s true that short flights tend to be more harmful to the climate per mile travelled than long-haul flights (because they have more empty seats, and because taking off and landing burns more fuel than cruising) but this doesn’t change the fact that the further you travel, the greater the emissions that will result. Is it really greener to go by train? As a rule, taking the train instead of the plane will substantially reduce your carbon emissions – perhaps by a factor of five to ten on a domestic trip. The benefits will be somewhat reduced as the journey gets longer. That’s partly because shorter flights are more polluting per passenger mile than longer ones, but it’s also because long train jour-neys usually necessitate sleeping onboard. Sleeper cars usually carry fewer passengers than regular carriages, so their emissions per passenger are higher. If, as is common in some countries, the train is powered by diesel rather than electricity, then the emissions will typically be higher still. Indeed, an old diesel sleeper train travelling a long distance might emit nearly as much CO2per passenger as a plane. Even then, the train will typically be greener once you consider the plane’s non-CO2 warming effects, but the fact remains that long-haul rail is not by any means inherently eco-friendly.