![CO2 emissions fraction of Aviation (%)](https://upload.wikimedia.org/wikipedia/commons/8/8e/CO2_emissions_fraction_of_Aviation_%28%25%29.png)
Like other emissions resulting from
fossil fuel
A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels m ...
combustion,
aircraft engine
An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many ...
s produce gases,
noise
Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference arise ...
, and
particulates
Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM) or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The ter ...
, raising
environment
Environment most often refers to:
__NOTOC__
* Natural environment, all living and non-living things occurring naturally
* Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
al concerns over their global effects and their effects on local air quality.
Jet airliners
A jet airliner or jetliner is an airliner powered by jet engines (passenger jet aircraft). Airliners usually have two or four jet engines; three-engined designs were popular in the 1970s but are less common today. Airliners are commonly cl ...
contribute to
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
by emitting
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
(), the best understood
greenhouse gas
A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
, and, with less
scientific understanding,
nitrogen oxides Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:
Charge-neutral
*Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide
*Nitrogen dioxide (), nitrogen(IV) oxide
*Nitrogen trioxide (), or ni ...
,
contrails
Contrails (; short for "condensation trails") or vapor trails are line-shaped clouds produced by aircraft engine exhaust or changes in air pressure, typically at aircraft cruising altitudes several miles above the Earth's surface. Contrails ar ...
and particulates.
Their
radiative forcing
Radiative forcing (or climate forcing) is the change in energy flux in the atmosphere caused by natural or anthropogenic factors of climate change as measured by watts / metre2. It is a scientific concept used to quantify and compare the external ...
is estimated at 1.3–1.4 that of alone, excluding induced
cirrus cloud
Cirrus ( cloud classification symbol: Ci) is a genus of high cloud made of ice crystals. Cirrus clouds typically appear delicate and wispy with white strands. Cirrus are usually formed when warm, dry air rises, causing water vapor deposition on ...
with a very low level of scientific understanding.
In 2018, global commercial operations generated 2.4% of all emissions.
[
Jet airliners have become 70% more fuel efficient between 1967 and 2007, and emissions per revenue ]ton-kilometer
The units of measurement in transportation describes the unit of measurement used to express various transportation quantities, as used in statistics, planning, and their related applications.
Transportation quantity
The currently popular units ...
(RTK) in 2018 were 47% of those in 1990. In 2018, emissions averaged 88 grams of per revenue passenger per km.
While the aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...
industry is more fuel efficient
Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
, overall emissions have risen as the volume of air travel
Air travel is a form of travel in vehicles such as airplanes, jet aircraft, helicopters, hot air balloons, blimps, gliders, hang gliders, parachutes, or anything else that can sustain flight. has increased. By 2020, aviation emissions were 70% higher than in 2005 and they could grow by 300% by 2050.[
]Aircraft noise pollution
Aircraft noise pollution refers to noise produced by aircraft in flight that has been associated with several negative stress-mediated health effects, from sleep disorders to cardiovascular ones. Governments have enacted extensive controls that a ...
disrupts sleep
Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...
, children's education and could increase cardiovascular risk
Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, ...
.
Airports
An airport is an aerodrome with extended facilities, mostly for commercial air transport. Airports usually consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surface ...
can generate water pollution
Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water ...
due to their extensive handling of jet fuel
Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial a ...
and deicing
Deicing is the process of removing snow, ice or frost from a surface. Anti-icing is the application of chemicals that not only deice but also remain on a surface and continue to delay the reformation of ice for a certain period of time, or preve ...
chemicals if not contained, contaminating nearby water bodies.
Aviation activities emit ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
and ultrafine particles
Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 0.1 μm or 100 nm in diameter).
Regulations do not exist for this size class of ambient air pollution particles, which are far smaller than the regulated PM10 and ...
, both of which are health hazard
A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would allow them, even just theoretically, to cause damage to health, life, property, or any other interest of value. The probabi ...
s. Piston engines used in general aviation
General aviation (GA) is defined by the International Civil Aviation Organization (ICAO) as all civil aviation aircraft operations with the exception of commercial air transport or aerial work, which is defined as specialized aviation services ...
burn Avgas
Avgas (aviation gasoline, also known as aviation spirit in the UK) is an aviation fuel used in aircraft with spark-ignited internal combustion engines. ''Avgas'' is distinguished from conventional gasoline (petrol) used in motor vehicles, w ...
, releasing toxic lead.
Aviation's environmental footprint can be reduced by better fuel economy in aircraft
The fuel economy in aircraft is the measure of the transport energy efficiency of aircraft.
Efficiency is increased with better aerodynamics and by reducing weight, and with improved engine BSFC and propulsive efficiency or TSFC.
Enduran ...
or Air Traffic Control
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airs ...
and flight routes can be optimized to lower non- effects on climate from , particulates or contrails.
Aviation biofuel
An aviation biofuel or bio-jet fuel Note: About">Investable Universe>About' or bio-aviation fuel (BAF) is a biofuel used to power aircraft and is said to be a sustainable aviation fuel (SAF). The International Air Transport Association (IATA) co ...
, emissions trading
Emissions trading is a market-based approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants. The concept is also known as cap and trade (CAT) or emissions trading scheme (ETS). Carbon emission t ...
and carbon offsetting
A carbon offset is a reduction or removal of emissions of carbon dioxide or other greenhouse gases made in order to compensate for emissions made elsewhere. Offsets are measured in tonnes of carbon dioxide-equivalent (CO2e). One ton of carbo ...
, part of the ICAO's CORSIA, can lower emissions. Aviation usage can be lowered by short-haul flight ban
A short-haul flight ban is a prohibition imposed by governments on airlines to establish and maintain a flight connection over a certain distance, or by organisations or companies on their employees for business travel using existing flight con ...
s, train connections, personal choices and aviation taxation and subsidies
Aviation taxation and subsidies includes taxes and subsidies related to aviation.
Taxation is one of several methods to mitigate the environmental impact of aviation.
Types of taxes
* Airport improvement fee, paid by passengers to the airp ...
. Fuel-powered aircraft may be replaced by hybrid electric aircraft A hybrid electric aircraft is an aircraft with a hybrid electric powertrain. As the energy density of lithium-ion batteries is much lower than aviation fuel, a hybrid electric powertrain may effectively increase flight range compared to pure electri ...
and electric aircraft
An electric aircraft is an aircraft powered by electricity.
Electric aircraft are seen as a way to reduce the environmental effects of aviation, providing zero emissions and quieter flights.
Electricity may be supplied by a variety of methods, ...
or by hydrogen-powered aircraft
A hydrogen-powered aircraft is an aeroplane that uses hydrogen fuel as a power source. Hydrogen can either be burned in a jet engine or another kind of internal combustion engine, or can be used to power a fuel cell to generate electricity to pow ...
.
Climate change
Factors
Airplanes emit gases (carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
, water vapor
(99.9839 °C)
, -
, Boiling point
,
, -
, specific gas constant
, 461.5 J/( kg·K)
, -
, Heat of vaporization
, 2.27 MJ/kg
, -
, Heat capacity
, 1.864 kJ/(kg·K)
Water vapor, water vapour or aqueous vapor is the gaseous pha ...
, nitrogen oxide Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:
Charge-neutral
*Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide
*Nitrogen dioxide (), nitrogen(IV) oxide
* Nitrogen trioxide (), or n ...
s or carbon monoxide
Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
− bonding with oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
to become upon release) and atmospheric particulates (incompletely burned hydrocarbons
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
, sulfur oxide
Sulfur oxide refers to many types of sulfur and oxygen containing compounds such as SO, SO2, SO3, S7O2, S6O2, S2O2, etc.
Sulfur oxide (SO''x'') refers to one or more of the following:
* Lower sulfur oxides (S''n''O, S7O2 and S6O2)
* Sulfur monox ...
s, black carbon
Chemically, black carbon (BC) is a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fue ...
), interacting among themselves and with the atmosphere.
While the main greenhouse gas
A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
emission from powered aircraft is , jet airliners
A jet airliner or jetliner is an airliner powered by jet engines (passenger jet aircraft). Airliners usually have two or four jet engines; three-engined designs were popular in the 1970s but are less common today. Airliners are commonly cl ...
contribute to climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
in four ways as they fly in the tropopause
The tropopause is the atmospheric boundary that demarcates the troposphere from the stratosphere; which are two of the five layers of the atmosphere of Earth. The tropopause is a thermodynamic gradient-stratification layer, that marks the end of ...
:
; Carbon dioxide ()
: emissions are the most significant and best understood contribution to climate change. The effects of emissions are similar regardless of altitude. Airport
An airport is an aerodrome with extended facilities, mostly for commercial air transport. Airports usually consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surface ...
ground vehicles, those used by passengers and staff to access airports, emissions generated by airport construction and aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
manufacturing also contribute to the greenhouse gas emissions
Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...
from the aviation industry.
; Nitrogen oxides Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:
Charge-neutral
*Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide
*Nitrogen dioxide (), nitrogen(IV) oxide
*Nitrogen trioxide (), or ni ...
(, nitric oxide
Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...
and nitrogen dioxide
Nitrogen dioxide is a chemical compound with the formula . It is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year for use primarily in the producti ...
)
: In the tropopause, emissions of favor ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
() formation in the upper troposphere
The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...
. At altitudes from , emissions result in greater concentrations of than surface emissions and these in turn have a greater global warming effect. The effect of surface concentrations are regional and local, but it becomes well mixed globally at mid and upper tropospheric levels. emissions also reduce ambient levels of methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
, another greenhouse gas, resulting in a climate cooling effect, though not offsetting the forming effect. Aircraft sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
and water emissions in the stratosphere
The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...
tend to deplete , partially offsetting the -induced increases, although these effects have not been quantified.[ Light aircraft and small commuter aircraft fly lower in the troposphere, not in the tropopause.
]
; Contrails and cirrus clouds
: Fuel burning produces water vapor, which condenses at high altitude, under cold and humid conditions, into visible line clouds: condensation trails (contrails). They are thought to have a global warming effect, though less significant than emissions. Contrails are uncommon from lower-altitude aircraft. Cirrus clouds can develop after the formation of persistent contrails and can have an additional global warming effect. Their global warming contribution is uncertain and estimating aviation's overall contribution often excludes cirrus cloud enhancement.[
; Particulates
: Compared with other emissions, ]sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ar ...
and soot
Soot ( ) is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolysed ...
particles have a smaller direct effect: sulfate particles have a cooling effect and reflect radiation, while soot has a warming effect and absorbs heat, while the clouds' properties and formation are influenced by particles. Contrails and cirrus clouds evolving from particles may have a greater radiative forcing effect than emissions. As soot particles are large enough to serve as condensation nuclei, they are thought to cause the most contrail formation. Soot production may be decreased by reducing the aromatic compound
Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past grouping ...
of jet fuel.
In 1999, the IPCC
The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) a ...
estimated aviation's radiative forcing in 1992 to be 2.7 (2 to 4) times that of alone − excluding the potential effect of cirrus cloud enhancement.[
This was updated for 2000, with aviation's radiative forcing estimated at 47.8 mW/m2, times the effect of emissions alone, 25.3 mW/m2.][
In 2005, research by David S. Lee, et al, published in the scientific journal '']Atmospheric Environment
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
'' estimated the cumulative radiative forcing effect of aviation at 55 mW/m2, which is twice the 28 mW/m2 radiative forcing effect of its emissions alone, excluding induced cirrus cloud, with a very low level of scientific understanding.
In 2012, research from Chalmers university estimated this weighting factor at 1.3–1.4 if aviation induced cirrus is not included, 1.7–1.8 if they are included (within a range of 1.3–2.9).
Uncertainties remain on the NOx–O3–CH4 interactions, aviation-produced contrails formation, the effects of soot aerosols on cirrus clouds and measuring non-CO2 radiative forcing.[
In 2018, represented 34.3 mW/m2 of aviation's effective radiative forcing (ERF, on the surface), with a high ]confidence level
In frequentist statistics, a confidence interval (CI) is a range of estimates for an unknown parameter. A confidence interval is computed at a designated ''confidence level''; the 95% confidence level is most common, but other levels, such as 9 ...
(± 6 mW/m2), 17.5 mW/m2 with a low confidence level (± 14) and contrail cirrus 57.4 mW/m2, also with a low confidence level (± 40).[
All factors combined represented 43.5 mW/m2 ( that of alone) excluding contrail cirrus and 101 mW/m2 (±45) including them, 3.5% of the anthropogenic ERF of 2290 mW/m2 (± 1100).]
Volume
By 2018, airline
An airline is a company that provides civil aviation, air transport services for traveling passengers and freight. Airlines use aircraft to supply these services and may form partnerships or Airline alliance, alliances with other airlines for ...
traffic reached 4.3 billion passengers with 37.8 million departures, an average of passengers per flight and 8.26 trillion RPK
The RPK (russian: Ручной пулемёт Калашникова/РПК, Ruchnoy Pulemyot Kalashnikova, link=no, English: "Kalashnikov hand-held machine gun"), sometimes retroactively termed the RPK-47, is a Soviet 7.62×39mm light machine ...
s, an average journey of , according to ICAO
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...
.
The traffic was experiencing continuous growth, doubling every 15 years, despite external shocks − a 4.3% average yearly growth and Airbus
Airbus SE (; ; ; ) is a European Multinational corporation, multinational aerospace corporation. Airbus designs, manufactures and sells civil and military aerospace manufacturer, aerospace products worldwide and manufactures aircraft througho ...
forecasts expect the growth to continue.
While the aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...
industry is more fuel efficient
Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
, halving the amount of fuel burned per flight compared to 1990 through technological advancement
Innovation is the practical implementation of ideas that result in the introduction of new goods or services or improvement in offering goods or services. ISO TC 279 in the standard ISO 56000:2020 defines innovation as "a new or changed entity ...
and operations improvements, overall emissions have risen as the volume of air travel
Air travel is a form of travel in vehicles such as airplanes, jet aircraft, helicopters, hot air balloons, blimps, gliders, hang gliders, parachutes, or anything else that can sustain flight. has increased.
Between 1960 and 2018, RPKs increased from 109 to 8,269 billion.[
In 1992, aircraft emissions represented 2% of all man-made emissions, having accumulated a little more than 1% of the total man-made increase over 50 years.]
By 2015, aviation accounted for 2.5% of global emissions.
In 2018, global commercial operations emitted 918 million tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s (Mt) of , 2.4% of all emissions: 747 Mt for passenger transport and 171 Mt for freight operations.
Between 1960 and 2018, emissions increased 6.8 times from to 1,034 million tonnes per year.[
Emissions from flights rose by 32% between 2013 and 2018.][
]
Between 1990 and 2006, greenhouse gas emissions from aviation increased by 87% in the European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
.
In 2010, about 60% of aviation emissions came from international flights, which are outside the emission reduction targets of the Kyoto Protocol
The Kyoto Protocol was an international treaty which extended the 1992 United Nations Framework Convention on Climate Change (UNFCCC) that commits state parties to reduce greenhouse gas emissions, based on the scientific consensus that (part ...
. International flights are not covered by the Paris Agreement
The Paris Agreement (french: Accord de Paris), often referred to as the Paris Accords or the Paris Climate Accords, is an international treaty on climate change. Adopted in 2015, the agreement covers climate change mitigation, Climate change a ...
, either, to avoid a patchwork of individual country regulations. That agreement was adopted by the International Civil Aviation Organization
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international sc ...
, however, capping airlines carbon emissions to the year 2020 level, while allowing airlines to buy carbon credits
A carbon credit is a generic term for any tradable certificate or permit representing the right to emit a set amount of carbon dioxide or the equivalent amount of a different greenhouse gas (tCO2e).
Carbon credits and carbon markets are a compo ...
from other industries and projects.
In 1992, aircraft radiative forcing
Radiative forcing (or climate forcing) is the change in energy flux in the atmosphere caused by natural or anthropogenic factors of climate change as measured by watts / metre2. It is a scientific concept used to quantify and compare the external ...
was estimated by the IPCC at 3.5% of the total man-made radiative forcing.
Per passenger
As it accounts for a large share of their costs, 28% by 2007, airlines have a strong incentive to lower their fuel consumption, reducing their environmental footprint.
Jet airliners have become 70% more fuel efficient between 1967 and 2007.[
Jetliner fuel efficiency improves continuously, 40% of the improvement come from engines and 30% from airframes.
Efficiency gains were larger early in the ]jet age
The Jet Age is a period in the history of aviation defined by the advent of aircraft powered by jet turbine engines, and by the social change this brought about.
Jet airliners were able to fly much higher, faster, and farther than older pisto ...
than later, with a 55–67% gain from 1960 to 1980 and a 20–26% gain from 1980 to 2000.
The average fuel burn of new aircraft fell 45% from 1968 to 2014, a compounded annual reduction of 1.3% with variable reduction rate.
By 2018, emissions per revenue ton-kilometer
The units of measurement in transportation describes the unit of measurement used to express various transportation quantities, as used in statistics, planning, and their related applications.
Transportation quantity
The currently popular units ...
(RTK) were more than halved compared to 1990, at 47%.
The aviation energy intensity
Energy intensity is a measure of the energy inefficiency of an economy. It is calculated as units of energy per unit of GDP.
* High energy intensities indicate a high price or cost of converting energy into GDP.
* Low energy intensity indicate ...
went from 21.2 to 12.3 MJ/RTK between 2000 and 2019, a % reduction.[
In 2018, emissions totalled 747 million tonnes for passenger transport, for 8.5 trillion ]revenue passenger kilometre
A passenger (also abbreviated as pax) is a person who travels in a vehicle, but does not bear any responsibility for the tasks required for that vehicle to arrive at its destination or otherwise operate the vehicle, and is not a steward. The ...
s (RPK), giving an average of 88 gram per RPK.[
The UK's Department for calculate a long-haul flight release 102g of per passenger kilometre, and 254g of equivalent, including non-CO2 greenhouse gas emissions, water vapor etc; for a domestic flight in Britain.]
The ICAO targets a 2% efficiency improvement per year between 2013 and 2050, while the IATA targets 1.5% for 2009–2020 and to cut net emissions in half by 2050 relative to 2005.
Evolution
In 1999, the IPCC estimated aviation's radiative forcing may represent 190 mW/m2 or 5% of the total man-made radiative forcing in 2050, with the uncertainty ranging from 100 to 500 mW/m2. If other industries achieve significant reductions in greenhouse gas emissions over time, aviation's share, as a proportion of the remaining emissions, could rise.
Alice Bows-Larkin estimated that the annual global emissions budget would be entirely consumed by aviation emissions to keep the climate change temperature increase below 2 °C by mid-century. Given that growth projections indicate that aviation will generate 15% of global emissions, even with the most advanced technology forecast, she estimated that to hold the risks of dangerous climate change to under 50% by 2050 would exceed the entire carbon budget in conventional scenarios.
In 2013, the National Center for Atmospheric Science at the University of Reading
The University of Reading is a public university in Reading, Berkshire, England. It was founded in 1892 as University College, Reading, a University of Oxford extension college. The institution received the power to grant its own degrees in 192 ...
forecast that increasing levels will result in a significant increase in in-flight turbulence experienced by transatlantic airline flights by the middle of the 21st century.
Aviation emissions grow despite efficiency innovations to aircraft, powerplants and flight operations.
Air travel continue to grow.
In 2015, the Center for Biological Diversity
The Center for Biological Diversity is a nonprofit membership organization known for its work protecting endangered species through legal action, scientific petitions, creative media and grassroots activism. It was founded in 1989 by Kieran Suckl ...
estimated that aircraft could generate of carbon dioxide emissions through 2050, consuming almost 5% of the remaining global carbon budget. Without regulation, global aviation emissions may triple by mid-century and could emit more than of carbon annually under a high-growth, business-as-usual scenario.
Many countries have pledged emissions reductions for the Paris Agreement, but the sum of these efforts and pledges remains insufficient and not addressing airplane pollution would be a failure despite technological and operational advancements.[
*]
The International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing carb ...
projects aviation share of global emissions may grow from 2.5% in 2019 to 3.5% by 2030.
By 2020, global international aviation emissions were around 70% higher than in 2005 and the ICAO forecasts they could grow by over further 300% by 2050 in the absence of additional measures.
By 2050, aviation's negative effects on climate could be decreased by a 2% increase in fuel efficiency and a decrease in emissions, due to advanced aircraft technologies, operational procedures and renewable alternative fuels decreasing radiative forcing due to sulfate aerosol and black carbon.[
]
Noise
Air traffic
Air Traffic are an English alternative rock band from Bournemouth signed to EMI Records. Formed in 2003, the band consists of Chris Wall (piano, lead vocals), David Ryan Jordan (Drums), Tom Pritchard (guitar) and Jim Maddock (bass guitar).
...
causes aircraft noise
Aircraft noise pollution refers to noise produced by aircraft in flight that has been associated with several negative stress-mediated health effects, from sleep disorders to cardiovascular ones. Governments have enacted extensive controls that a ...
, which disrupts sleep, adversely affects children's school performance and could increase cardiovascular risk
Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, ...
for airport neighbours. Sleep disruption can be reduced by banning or restricting flying at night, but disturbance progressively decreases and legislation differs across countries.[
The ]ICAO
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...
Chapter 14 noise standard applies for aeroplanes submitted for certification after 31 December 2017, and after 31 December 2020 for aircraft below , 7 EPNdB (cumulative) quieter than Chapter4. The FAA
The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...
Stage 5 noise standards are equivalent. Higher bypass ratio
The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for ev ...
engines produce less noise. The PW1000G
The Pratt & Whitney PW1000G, also called the Geared Turbofan (GTF), is a high-bypass geared turbofan engine family produced by Pratt & Whitney.
After many demonstrators, the program was launched with the Mitsubishi MRJ's PW1200G in March 2008, ...
is presented as 75% quieter than previous engines. Serrated edges or 'chevrons' on the back of the nacelle
A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
reduce noise.[
A ]Continuous Descent Approach
Continuous descent approach (CDA), also known as optimized profile descent (OPD), is a method by which aircraft approach airports prior to landing. It is designed to reduce fuel consumption and noise compared to other conventional descents. Inst ...
(CDA) is quieter as less noise is produced while the engines are near idle power. CDA can reduce noise on the ground by ~1–5 dB per flight.
Water pollution
Airports can generate significant water pollution
Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water ...
due to their extensive use and handling of jet fuel, lubricants and other chemicals. Chemical spills can be mitigated or prevented by spill containment
Spill containment is where spills of chemicals, oils, sewage etc. are contained within a barrier or drainage system rather than being absorbed at the surface. One method is to use an inflatable stopper or pneumatic bladder which is inserted into t ...
structures and clean-up equipment such as vacuum trucks, portable berms and absorbents.
Deicing
Deicing is the process of removing snow, ice or frost from a surface. Anti-icing is the application of chemicals that not only deice but also remain on a surface and continue to delay the reformation of ice for a certain period of time, or preve ...
fluids used in cold weather can pollute water, as most of them fall to the ground and surface runoff
Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...
can carry them to nearby streams, rivers or coastal waters.[ Deicing fluids are based on ]ethylene glycol
Ethylene glycol (IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odo ...
or propylene glycol
Propylene glycol (IUPAC nomenclature, IUPAC name: propane-1,2-diol) is a viscous, colorless liquid, which is nearly odorless but possesses a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH.
Containing two Alcohol (chemistry), alcoho ...
.[ Airports use pavement deicers on paved surfaces including runways and taxiways, which may contain ]potassium acetate
Potassium acetate (CH3COOK) is the potassium salt of acetic acid. It is a hygroscopic solid at room temperature.
Preparation
It can be prepared by treating a potassium-containing base such as potassium hydroxide or potassium carbonate with acetic ...
, glycol compounds, sodium acetate
Sodium acetate, CH3COONa, also abbreviated Na O Ac, is the sodium salt of acetic acid. This colorless deliquescent salt has a wide range of uses.
Applications
Biotechnological
Sodium acetate is used as the carbon source for culturing bacteria ...
, urea
Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid.
Urea serves an important r ...
or other chemicals.
During degradation in surface waters, ethylene and propylene glycol exert high levels of biochemical oxygen demand
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen (DO) needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at a certain temperature over a specific time period. T ...
, consuming oxygen needed by aquatic life. Microbial populations decomposing propylene glycol consume large quantities of dissolved oxygen
Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It ca ...
(DO) in the water column
A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...
.[
Fish, ]macroinvertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate s ...
s and other aquatic organisms need sufficient dissolved oxygen levels in surface waters. Low oxygen concentrations reduce usable aquatic habitat because organisms die if they cannot move to areas with sufficient oxygen levels. Bottom feeder
A bottom feeder is an aquatic animal that feeds on or near the bottom of a body of water. Biologists often use the terms ''benthos''—particularly for invertebrates such as shellfish, crabs, crayfish, sea anemones, starfish, snails, bri ...
populations can be reduced or eliminated by low DO levels, changing a community's species profile or altering critical food-web
A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one ...
interactions.
Air pollution
Aviation is the main human source of ozone, a respiratory health hazard
A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would allow them, even just theoretically, to cause damage to health, life, property, or any other interest of value. The probabi ...
, causing an estimated 6,800 premature deaths per year.
Aircraft engines emit ultrafine particles
Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 0.1 μm or 100 nm in diameter).
Regulations do not exist for this size class of ambient air pollution particles, which are far smaller than the regulated PM10 and ...
(UFPs) in and near airports, as does ground support equipment
File:Qatar Airways Airbus A380-800 at Heathrow Airport Terminal 4 before Flying to Doha, 6 Jan 2015.jpg, Qatar Airways Airbus A380-800 on apron outside Heathrow Terminal 4 with a wide range of ground handling equipment around such as aircraft con ...
. During takeoff, 3 to 50 × 1015 particles were measured per kg of fuel burned, while significant differences are observed depending on the engine. Other estimates include 4 to 200 × 1015 particles for 0.1–0.7 gram, or 14 to 710 × 1015 particles, or 0.1–10 × 1015 black carbon
Chemically, black carbon (BC) is a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fue ...
particles for 0.046–0.941 g.
In the United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, 167,000 piston aircraft engine
An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many ...
s, representing three-quarters of private airplanes, burn Avgas
Avgas (aviation gasoline, also known as aviation spirit in the UK) is an aviation fuel used in aircraft with spark-ignited internal combustion engines. ''Avgas'' is distinguished from conventional gasoline (petrol) used in motor vehicles, w ...
, releasing lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
into the air. The Environmental Protection Agency
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
estimated this released 34,000 tons of lead into the atmosphere between 1970 and 2007. The Federal Aviation Administration
The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...
recognizes inhaled or ingested lead leads to adverse effects on the nervous system, red blood cells, and cardiovascular and immune systems. Lead exposure in infants and young children may contribute to behavioral and learning problems and lower IQ.
Mitigation
In February 2021, Europe's aviation sector unveiled its ''Destination 2050'' sustainability initiative towards zero emissions by 2050:
* aircraft technology improvements for 37% emission reductions;
* sustainable aviation fuel
An aviation biofuel or bio-jet fuel Note: About">Investable Universe>About' or bio-aviation fuel (BAF) is a biofuel used to power aircraft and is said to be a sustainable aviation fuel (SAF). The International Air Transport Association (IATA) co ...
s (SAFs) for 34%;
* economic measures for 8%;
* air traffic management 334x334px,
Air traffic management (ATM) is an aviation term encompassing all systems that assist aircraft to depart from an aerodrome, transit airspace, and land at a destination aerodrome, consisting of air traffic services (ATS) including air tr ...
(ATM) and operations improvements for 6%;
while air traffic should grow by 1.4% per year between 2018 and 2050.[
The initiative is led by ]ACI Europe
Airports Council International Europe (ACI EUROPE) is a European industry trade association which advances the collective interests of Europe's airports and promotes professional excellence in airport management and operations. The members are over ...
, ASD Europe, A4E
A4e (''Action for Employment'') was a for-profit, welfare-to-work company based in the United Kingdom. The company began in Sheffield in 1991 with the objective to provide redundant steelworkers with the training required to obtain new jobs.
Th ...
, CANSO
The Civil Air Navigation Services Organisation (CANSO) is a representative body of companies that provide air traffic control. It represents the interests of Air Navigation Service Providers (ANSPs). CANSO members are responsible for supporting ov ...
and ERA
An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth.
Comp ...
.
Reducing air travel
Aviation's environmental footprint would be mitigated by reducing air travel, route optimization, emission caps, short-distance restrictions, increased taxation, and decreased subsidies.
;Route optimization
An improved Air Traffic Management 334x334px,
Air traffic management (ATM) is an aviation term encompassing all systems that assist aircraft to depart from an aerodrome, transit airspace, and land at a destination aerodrome, consisting of air traffic services (ATS) including air tr ...
system, with more direct routes than suboptimal air corridor
In the United States, airways or air routes are defined by the Federal Aviation Administration (FAA) in two ways:
"VOR Federal airways and Low/Medium Frequency (L/MF) (Colored) Federal airways"
These are designated routes which aeroplanes f ...
s and optimized cruising altitudes, would allow airlines to reduce their emissions by up to 18%.[ In the European Union, a ]Single European Sky
The Single European Sky (SES) is a European Commission initiative that seeks to reform the European air traffic management system through a series of actions carried out in four different levels (institutional, operational, technological and contr ...
has been proposed since 1999 to avoid overlapping airspace restrictions between EU countries and to reduce emissions. By 2007, 12 million tons of emissions per year were caused by the lack of a Single European Sky.[ As of September 2020, the Single European Sky has still not been completely achieved, costing 6 billion euros in delays and causing 11.6 million tonnes of excess emissions.
;Emissions trading
]ICAO
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...
has endorsed emissions trading
Emissions trading is a market-based approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants. The concept is also known as cap and trade (CAT) or emissions trading scheme (ETS). Carbon emission t ...
to reduce aviation emission, guidelines were to be presented to the 2007 ICAO Assembly. Within the European Union, the European Commission
The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body o ...
has included aviation in the European Union Emissions Trading Scheme
The European Union Emissions Trading System (EU ETS) is a "cap and trade" scheme where a limit is placed on the right to emit specified pollutants over an area and companies can trade emission rights within that area. It covers around 45% of th ...
operated since 2012, capping airline emissions, providing incentives to lower emissions through more efficient technology or to buy carbon credit
A carbon credit is a generic term for any tradable certificate or permit representing the right to emit a set amount of carbon dioxide or the equivalent amount of a different greenhouse gas (tCO2e).
Carbon credits and carbon markets are a compo ...
s from other companies. The Centre for Aviation, Transport and Environment at Manchester Metropolitan University
Manchester Metropolitan University is located in the centre of Manchester, England. The university has over 40,000 students and over 4,000 members of staff. It is home to four faculties (Arts and Humanities, Business and Law, Health and Educat ...
estimates the only way to lower emissions is to put a price on carbon and to use market-based measures like the EU ETS.
;Short-haul flight ban
; Train connections
Train connections reduce feeder flights.[ By March 2019, ]Lufthansa
Deutsche Lufthansa AG (), commonly shortened to Lufthansa, is the flag carrier of Germany. When combined with its subsidiaries, it is the second- largest airline in Europe in terms of passengers carried. Lufthansa is one of the five founding m ...
offered connections through Frankfurt with the Deutsche Bahn
The (; abbreviated as DB or DB AG) is the national railway company of Germany. Headquartered in the Bahntower in Berlin, it is a joint-stock company ( AG). The Federal Republic of Germany is its single shareholder.
describes itself as the se ...
(AIRail Service
AiRail Service is offered by Deutsche Bahn AG in cooperation with Lufthansa, American Airlines and Emirates. It is one example of several a dedicated air-rail alliances currently operating worldwide.
AiRail Service is currently offered between ...
) and Air France
Air France (; formally ''Société Air France, S.A.''), stylised as AIRFRANCE, is the flag carrier of France headquartered in Tremblay-en-France. It is a subsidiary of the Air France–KLM Group and a founding member of the SkyTeam global air ...
offered TGV
The TGV (french: Train à Grande Vitesse, "high-speed train"; previously french: TurboTrain à Grande Vitesse, label=none) is France's intercity high-speed rail service, operated by SNCF. SNCF worked on a high-speed rail network from 1966 to 19 ...
connections through Paris. In October 2018, Austrian Airlines
Austrian Airlines AG, often shortened to Austrian, is the flag carrier of Austria and a subsidiary of the Lufthansa Group. The airline is headquartered on the grounds of Vienna International Airport in Schwechat where it also maintains its hub ...
and the Austrian Federal Railways
Austrian may refer to:
* Austrians, someone from Austria or of Austrian descent
** Someone who is considered an Austrian citizen, see Austrian nationality law
* Austrian German dialect
* Something associated with the country Austria, for example: ...
introduced train connections through Vienna Airport
Vienna International Airport (german: Flughafen Wien-Schwechat; ) is the international airport of Vienna, the capital of Austria, located in Schwechat, southeast of central Vienna and west of Bratislava, the capital of Slovakia. It is the ...
. In March 2019, the Dutch cabinet
The cabinet of the Netherlands ( nl, Nederlands kabinet) is the main executive body of the Netherlands. The current cabinet of the Netherlands is the Fourth Rutte cabinet, which has been in power since 10 January 2022. It is headed by Prime Minis ...
was working on an Amsterdam connection via NS International
NS International, formerly ''NS Hispeed'', is a rail operator in the Netherlands that operates international intercity and high-speed connections to several European cities. The operator is a subsidiary of the ''Nederlandse Spoorwegen''.
History ...
or Thalys
Thalys (French: ) is a French-Belgian high-speed train operator originally built around the LGV Nord high-speed line between Paris and Brussels. This track is shared with Eurostar trains that go from Paris, Brussels or Amsterdam to London via Li ...
. By July 2020, Lufthansa and Deutsche Bahn expanded their offer through Frankfurt Airport
Frankfurt Airport (; german: link=no, Flughafen Frankfurt Main , also known as ''Rhein-Main-Flughafen'') is a major international airport located in Frankfurt, the fifth-largest city of Germany and one of the world's leading financial centres ...
to 17 major cities.
; International conferences
Most international professional
A professional is a member of a profession or any person who works in a specified professional activity. The term also describes the standards of education and training that prepare members of the profession with the particular knowledge and skil ...
or academic conference
An academic conference or scientific conference (also congress, symposium, workshop, or meeting) is an event for researchers (not necessarily academics) to present and discuss their scholarly work. Together with academic or scientific journals an ...
attendants travel by plane, conference travel is often regarded as an employee benefit
Employment is a relationship between two parties regulating the provision of paid labour services. Usually based on a contract, one party, the employer, which might be a corporation, a not-for-profit organization, a co-operative, or any othe ...
as costs are supported by employers. By 2003, Access Grid technology had hosted several international conferences. The Tyndall Centre has reported means to change common institutional and professional practices.
; Flight shame
In Sweden the concept of "flight shame
Flight shame or ''flygskam'' is an anti-flying social movement, with the aim of reducing the environmental impact of aviation. Flight shame refers to an individual's uneasiness over engaging in consumption that is energy-intense and climatical ...
" or "flygskam" has been cited as a cause of falling air travel. Swedish rail company SJ AB
SJ (formally ''SJ AB'') is a government-owned passenger train operator in Sweden. SJ was created in 2001, out of the public transport division of ''Statens Järnvägar'', when the former government agency was divided into six separate government- ...
reports that twice as many Swedish people chose to travel by train instead of by air in summer 2019 compared with the previous year. Swedish airports operator Swedavia
Swedavia AB is a Swedish state-owned company, which owns and operates ten of airports of Sweden, Sweden's busiest airports. It has its head office at the air traffic control tower of Stockholm-Arlanda Airport in Sigtuna Municipality near Stockholm ...
reported 4% fewer passengers across its 10 airports in 2019 compared to the previous year: a 9% drop for domestic passengers and 2% for international passengers.
The estimates that 3% of the global population take regular flights.[
Stefan Gössling of the ]Western Norway Research Institute
The Western Norway Research Institute (WRNI, Vestlandsforsking in Norwegian), is an assignment based research foundation founded by the county municipality of Sogn og Fjordane. Located in the Fosshaugane Campus, of the Sogn og Fjordane University ...
estimates 1% of the world population emits half of commercial aviation's CO2, while close to 90% does not fly in a given year.
In early 2022, the European Investment Bank
The European Investment Bank (EIB) is the European Union's investment bank and is owned by the EU Member States. It is one of the largest supranational lenders in the world. The EIB finances and invests both through equity and debt solutions ...
published the results of its 2021–2022 Climate Survey, showing that 52% of Europeans under 30, 37% of people between 30 and 64 and 25% for people aged 65 and above plan to travel by air for their summer holidays in 2022; and 27% of those under 30, 17% for people aged 30–64 and 12% for people aged 65 and above plan to travel by air to a faraway destination.
; ICAO regulation and CORSIA
In 2016, the International Civil Aviation Organization
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international sc ...
committed to improve aviation fuel efficiency by 2% per year and to stabilize carbon emissions
Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and larg ...
from 2020.[
To achieve these goals, multiple measures have been planned: more fuel-efficient aircraft technology; development and deployment of sustainable aviation fuels; Improved air traffic management; market-based measures like ]emission trading
Emissions trading is a market-based approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants. The concept is also known as cap and trade (CAT) or emissions trading scheme (ETS). Carbon emission t ...
, levies, and carbon offsetting
A carbon offset is a reduction or removal of emissions of carbon dioxide or other greenhouse gases made in order to compensate for emissions made elsewhere. Offsets are measured in tonnes of carbon dioxide-equivalent (CO2e). One ton of carbo ...
, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA).
Taxation and subsidies
Financial measures can discourage airline passengers and promote other transportation mode
Mode of transport is a term used to distinguish between different ways of transportation or transporting people or goods. The different modes of transport are air, water, and land transport, which includes rails or railways, road and off-road t ...
s and motivates airlines to improve fuel efficiency. Aviation taxation include:
* air passenger taxes, paid by passengers for environmental reasons, may be variable by distance and include domestic flights;
* departure tax
A departure tax is a fee charged (under various names) by a country when a person is leaving the country.
Background
Some countries charge a departure tax only when a person is leaving by air. In these cases, the departure tax can be ''de fa ...
es, paid by passengers leaving the country, sometimes also applies outside aviation;
* jet fuel taxes, paid by airlines for the consumed jet fuel, like the kerosene tax
The kerosene tax (German: ''Kerosinsteuer'', French: ''taxe kérosène''; Dutch: ''kerosinetaks'') is an ecotax on the kerosene-based jet fuel in commercial aviation, which can be levied within and by the European Union. The legal basis for it ...
for the European Union or fuel taxes in the United States
The United States federal excise tax on gasoline is 18.4 cents per gallon and 24.4 cents per gallon for diesel fuel.http://www.fhwa.dot.gov/infrastructure/gastax.cfm US Department of Transportation, Federal Highway Administration: When did the Fed ...
.
Consumer behavior can be influenced by cutting subsidies for unsustainable aviation and subsidising the development of sustainable alternatives.
By September–October 2019, a carbon tax on flights would be supported by 72% of the EU citizens, in a poll conducted for the European Investment Bank
The European Investment Bank (EIB) is the European Union's investment bank and is owned by the EU Member States. It is one of the largest supranational lenders in the world. The EIB finances and invests both through equity and debt solutions ...
.
Aviation taxation could reflect all its external costs
In economics, an externality or external cost is an indirect cost or benefit to an uninvolved third party that arises as an effect of another party's (or parties') activity. Externalities can be considered as unpriced goods involved in either co ...
and could be included in an emissions trading scheme.
International aviation emissions escaped international regulation until the ICAO
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...
triennial conference in 2016 agreed on the CORSIA offset scheme.
Due to low or nonexistent taxes on aviation fuel, air travel has a competitive advantage over other transportation modes.
Alternative fuels and technology
Aviation biofuels
Hydrogen and e-fuel
In 2020, Airbus unveiled liquid-hydrogen-powered aircraft
A hydrogen-powered aircraft is an aeroplane that uses hydrogen fuel as a power source. Hydrogen can either be burned in a jet engine or another kind of internal combustion engine, or can be used to power a fuel cell to generate electricity to pow ...
concepts as zero-emissions airliners, poised for 2035.
Aviation, like industrial processes that cannot be electrified, could use primarily Hydrogen-based fuel.
A 2020 study by the EU Clean Sky
The Clean Sky Joint Undertaking (CSJU) is a public-private partnership between the European Commission and the European aeronautics industry that coordinates and funds research activities to deliver significantly quieter and more environmentally ...
2 and Fuel Cells and Hydrogen 2 Joint Undertakings found that hydrogen could power aircraft by 2035 for short-range aircraft.[ A short-range aircraft (< ) with hybrid ]Fuel cell
A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most batteries in requ ...
/Turbines could reduce climate impact by 70-80% for a 20-30% additional cost, a medium-range airliner with H2 turbines could have a 50-60% reduced climate impact for a 30-40% overcost, and a long-range aircraft (> ) also with H2 turbines could reduce climate impact by 40-50% for a 40-50% additional cost.[ Research and development would be required, in aircraft technology and into hydrogen infrastructure, regulations and certification standards.]
The Potsdam Institute for Climate Impact Research
The Potsdam Institute for Climate Impact Research (PIK, German: ''Potsdam-Institut für Klimafolgenforschung'') is a German government-funded research institute addressing crucial scientific questions in the fields of global change, climate imp ...
reported a €800–1,200 mitigation cost per ton of for hydrogen-based e-fuels.[
Those could be reduced to €20–270 per ton of in 2050, but maybe not early enough to replace fossil fuels.][
Climate policies could bear the risk of e-fuel uncertain availability, and Hydrogen and e-fuels may be prioritised when direct ]electrification
Electrification is the process of powering by electricity and, in many contexts, the introduction of such power by changing over from an earlier power source.
The broad meaning of the term, such as in the history of technology, economic histor ...
is inaccessible.
Electric aircraft
Electric aircraft
An electric aircraft is an aircraft powered by electricity.
Electric aircraft are seen as a way to reduce the environmental effects of aviation, providing zero emissions and quieter flights.
Electricity may be supplied by a variety of methods, ...
operations do not produce any emissions and electricity can be generated by renewable energy
Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
. Lithium-ion batteries
A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also se ...
including packaging and accessories gives a 160 Wh/kg energy density
In physics, energy density is the amount of energy stored in a given system or region of space per unit volume. It is sometimes confused with energy per unit mass which is properly called specific energy or .
Often only the ''useful'' or extract ...
while aviation fuel gives 12,500 Wh/kg. As electric machines and converters are more efficient, their shaft power available is closer to 145 Wh/kg of battery while a gas turbine
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directi ...
gives 6,545 Wh/kg of fuel: a :1 ratio. For Collins Aerospace
Collins Aerospace is an American technology corporation that is one of the world's largest suppliers of aerospace and defense products. Headquartered in Charlotte, North Carolina, it is a subsidiary of Raytheon Technologies.
History
On No ...
, this 1:50 ratio forbids electric propulsion for long-range
Range may refer to:
Geography
* Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra)
** Mountain range, a group of mountains bordered by lowlands
* Range, a term used to i ...
aircraft. By November 2019, the German Aerospace Center
The German Aerospace Center (german: Deutsches Zentrum für Luft- und Raumfahrt e.V., abbreviated DLR, literally ''German Center for Air- and Space-flight'') is the national center for aerospace, energy and transportation research of Germany ...
estimated large electric planes could be available by 2040. Large, long-haul aircraft are unlikely to become electric before 2070 or within the 21st century, whilst smaller aircraft can be electrified. As of May 2020, the largest electric airplane was a modified Cessna 208B Caravan.
For the UK's Committee on Climate Change (CCC), huge technology shifts are uncertain, but consultancy Roland Berger
Roland Berger (born 22 November 1937) is a German entrepreneur, consultant and philanthropist.
Life
Roland Berger was born in Berlin in 1937 as Robert Altmann; his family name changed later, after his father, Georg L. Berger, married his mot ...
points to 80 new electric aircraft programmes in 2016–2018, all-electric for the smaller two-thirds and hybrid
Hybrid may refer to:
Science
* Hybrid (biology), an offspring resulting from cross-breeding
** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species
** Hybridity, the property of a hybrid plant which is a union of two dif ...
for larger aircraft, with forecast commercial service dates in the early 2030s on short-haul routes like London to Paris, with all-electric aircraft not expected before 2045. Berger predicts a 24% share for aviation by 2050 if fuel efficiency improves by 1% per year and if there are no electric or hybrid aircraft, dropping to 3–6% if 10-year-old aircraft are replaced by electric or hybrid aircraft due to regulatory constraints, starting in 2030, to reach 70% of the 2050 fleet. This would greatly reduce the value of the existing fleet of aircraft, however.
Limits to the supply of battery cells could hamper their aviation adoption, as they compete with other industries like electric vehicle
An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...
s.
Lithium-ion batteries
A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also se ...
have proven fragile and fire-prone and their capacity deteriorates with age. However, alternatives are being pursued, such as sodium-ion batteries.
Non- emissions
Besides carbon dioxide, aviation produces nitrogen oxides (), particulates, unburned hydrocarbon
Unburned hydrocarbons (UHCs) are the hydrocarbons emitted after petroleum is burned in an engine.
When unburned fuel is emitted from a combustor, the emission is caused by fuel "avoiding" the flame zones. For example, in piston engines, some of th ...
s (UHC) and contrail
Contrails (; short for "condensation trails") or vapor trails are line-shaped clouds produced by aircraft engine exhaust or changes in air pressure, typically at aircraft cruising altitudes several miles above the Earth's surface. Contrails ar ...
s. Flight routes can be optimized: modelling , and effects of transatlantic flight
A transatlantic flight is the flight of an aircraft across the Atlantic Ocean from Europe, Africa, South Asia, or the Middle East to North America, Central America, or South America, or ''vice versa''. Such flights have been made by fixed-wing air ...
s in winter shows westbound flights climate forcing can be lowered by up to 60% and ~25% for jet stream
Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...
-following eastbound flights, costing 10–15% more due to longer distances and lower altitudes consuming more fuel, but 0.5% costs increase can reduce climate forcing by up to 25%.
A 2000 feet (~600 m) lower cruise altitude than the optimal altitude has a % lower radiative forcing, while a 2000 feet higher cruise altitude % higher radiative forcing.
; Nitrogen oxides ()
: As designers work to reduce emissions from jet engine
A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, Pump-jet, water jet, and hybrid propulsion, the term ...
s, they fell by over 40% between 1997 and 2003. Cruising at a lower altitude could reduce -caused radiative forcing from 5 mW/m2 to ~3 mW/m2.
; Particulates
: Modern engines are designed so that no smoke is produced at any point in the flight while particulates and smoke were a problem with early jet engines at high power settings.[
; Unburned hydrocarbons (UHC)
: Produced by ]incomplete combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combusti ...
, more unburned hydrocarbons are produced with low compressor pressures and/or relatively low combustor temperatures, they have been eliminated in modern jet engines through improved design and technology, like particulates.[
; Contrails
: ]Contrail
Contrails (; short for "condensation trails") or vapor trails are line-shaped clouds produced by aircraft engine exhaust or changes in air pressure, typically at aircraft cruising altitudes several miles above the Earth's surface. Contrails ar ...
formation would be reduced by lowering the cruise altitude
Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...
with slightly increased flight times, but this would be limited by airspace
Airspace is the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere. It is not the same as aerospace, which is the ...
capacity, especially in Europe and North America, and increased fuel burn due to lower efficiency at lower altitudes, increasing emissions by 4%. Contrail radiative forcing could be minimized by schedule
A schedule or a timetable, as a basic time-management tool, consists of a list of times at which possible tasks, events, or actions are intended to take place, or of a sequence of events in the chronological order in which such things are i ...
s: night flights cause 60–80% of the forcing for only 25% of the air traffic, while winter
Winter is the coldest season of the year in polar and temperate climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Different cultures ...
flights contribute half of the forcing for only 22% of the air traffic. As 2% of flights are responsible for 80% of contrail radiative forcing, changing a flight altitude by to avoid high humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.
Humidity depe ...
for 1.7% of flights would reduce contrail formation by 59%.
National carbon budgets
In UK, transportation replaced power generation as the largest emissions source. This includes aviation's 4% contribution. This is expected to expand until 2050 and passenger demand may need to be reduced.[ For the UK ]Committee on Climate Change
The Climate Change Committee (CCC), originally named the Committee on Climate Change, is an independent non-departmental public body, formed under the Climate Change Act (2008) to advise the United Kingdom and devolved Governments and Parliament ...
(CCC), the UK target of an 80% reduction from 1990 to 2050 was still achievable from 2019, but the committee suggests that the Paris Agreement should tighten its emission targets.[
Their position is that emissions in problematic sectors, like aviation, should be offset by ]greenhouse gas removal
Carbon dioxide removal (CDR), also known as negative emissions, is a process in which carbon dioxide gas () is removed from the atmosphere and sequestered for long periods of time. Similarly, greenhouse gas removal (GGR) or negative greenho ...
, carbon capture and storage
Carbon capture and storage (CCS) or carbon capture and sequestration is the process of capturing carbon dioxide (CO2) before it enters the atmosphere, transporting it, and storing it (carbon sequestration) for centuries or millennia. Usually th ...
and reforestation.[
In December 2020, the UK Climate Change Committee said that: "Mitigation options considered include demand management, improvements in aircraft efficiency (including use of hybrid electric aircraft), and use of sustainable aviation fuels (biofuels, biowaste to jet and synthetic jet fuels) to displace fossil jet fuel." The UK will include international aviation and shipping in their ]carbon budget
A carbon budget is "the maximum amount of cumulative net global anthropogenic carbon dioxide () emissions that would result in limiting global warming to a given level with a given probability, taking into account the effect of other anthropogen ...
s and hopes other countries will too.
Carbon offsetting
A carbon offset is a means of compensating aviation emissions by saving enough carbon or absorbing carbon back into plants through photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
(for example, by planting trees
Tree-planting is the process of transplanting tree seedlings, generally for forestry, land reclamation, or landscaping purpose. It differs from the transplantation of larger trees in arboriculture, and from the lower cost but slower and less re ...
through reforestation
Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting.
Management
A debate ...
or afforestation
Afforestation is the establishment of a forest or stand of trees (forestation) in an area where there was no previous tree cover. Many government and non-governmental organizations directly engage in afforestation programs to create forests a ...
) to balance the carbon emitted by a particular action.
; Consumer option
: Some airlines offer carbon offsets to passengers to cover the emissions created by their flight, invested in green technology
Environmental technology (envirotech) or green technology (greentech), also known as ''clean technology'' (''cleantech''), is the application of one or more of environmental science, green chemistry, environmental monitoring and electronic device ...
such as renewable energy and research into future technology. Airlines offering carbon offsets include British Airways
British Airways (BA) is the flag carrier airline of the United Kingdom. It is headquartered in London
London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a populati ...
, Continental Airlines
Continental Airlines, simply known as Continental, was a major United States airline founded in 1934 and eventually headquartered in Houston, Texas. It had ownership interests and brand partnerships with several carriers.
Continental started o ...
, easyJet
EasyJet plc (styled as easyJet) is a British multinational low-cost airline group headquartered at London Luton Airport. It operates domestic and international scheduled services on 927 routes in more than 34 countries via its affiliate airli ...
,; and also Air Canada
Air Canada is the flag carrier and the largest airline of Canada by the size and passengers carried. Air Canada maintains its headquarters in the borough of Saint-Laurent, Montreal, Quebec. The airline, founded in 1937, provides scheduled and ...
, Air New Zealand
Air New Zealand Limited () is the flag carrier airline of New Zealand. Based in Auckland, the airline operates scheduled passenger flights to 20 domestic and 30 international destinations in 18 countries, primarily around and within the Pacific ...
, Delta Air Lines
Delta Air Lines, Inc., typically referred to as Delta, is one of the major airlines of the United States and a legacy carrier. One of the List of airlines by foundation date, world's oldest airlines in operation, Delta is headquartered in Atla ...
, Emirates Airlines
Emirates ( ar, طَيَران الإمارات DMG: ''Ṭayarān Al-Imārāt'') is one of two flag carriers of the United Arab Emirates (the other being Etihad). Based in Garhoud, Dubai, the airline is a subsidiary of The Emirates Group, which ...
, Gulf Air
Gulf Air ( ar, طيران الخليج ''Ṭayarān al-Khalīj'') is the state-owned airline and the flag carrier of Bahrain, which was founded in 1950 by British Pilot Freddie Bosworth as Gulf Aviation. Headquartered in Muharraq, the airline ...
, Jetstar
Jetstar Airways Pty Ltd, operating as Jetstar, is an Australian low-cost airline (self-described as "value-based") headquartered in Melbourne. It is a wholly owned subsidiary of Qantas, created in response to the threat posed by airline Virgi ...
, Lufthansa, Qantas
Qantas Airways Limited ( ) is the flag carrier of Australia and the country's largest airline by fleet size, international flights, and international destinations. It is the world's third-oldest airline still in operation, having been founded ...
, United Airlines
United Airlines, Inc. (commonly referred to as United), is a major American airline headquartered at the Willis Tower in Chicago, Illinois. and Virgin Australia
Virgin Australia, the trading name of Virgin Australia Airlines Pty Ltd, is an Australian-based airline. It is the largest airline by fleet size to use the Virgin Group, Virgin brand. It commenced services on 31 August 2000 as ''Virgin Blue ...
. Consumers can also purchase offsets on the individual market. There are certification standards for these, including the Gold Standard
A gold standard is a monetary system in which the standard economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the early 1920s, and from the la ...
and the Green-e.
Airline offsets
Some airlines have been carbon-neutral like Costa Rican Nature Air, or claim to be, like Canadian Harbour Air Seaplanes
Harbour Air Seaplanes is a scheduled floatplane service, tour and charter airline based in Richmond, British Columbia, Canada. The predominantly seaplane airline specializes in routes between Vancouver, Nanaimo, Victoria, Sechelt, Comox, Whis ...
. Long-haul low-cost venture Fly POP aims to be carbon neutral.
In 2019, Air France announced it would offset emissions on its 450 daily domestic flights, that carry 57,000 passengers, from January 2020, through certified projects.
The company will also offer its customers the option to voluntarily compensate for all their flights and aims to reduce its emissions by 50% per pax/km by 2030, compared to 2005.
Starting in November 2019, UK budget carrier EasyJet decided to offset carbon emissions for all its flights, through investments in atmospheric carbon
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A ...
reduction projects.
It claims to be the first major operator to be carbon neutral, at a cost of £25 million for its 2019–20 financial year.
Its emissions were 77 g per passenger in its 2018–19 financial year, down from 78.4 g the previous year.
From January 2020, British Airways began offsetting its 75 daily domestic flights emissions through carbon-reduction project investments.
The airline seeks to become carbon neutral by 2050 with fuel-efficient aircraft, sustainable fuels and operational changes.
Passengers flying overseas can offset their flights for £1 to Madrid in economy or £15 to New York in business-class.
US low-cost carrier JetBlue
JetBlue Airways Corporation (stylized as jetBlue) is a major American low cost airline, and the seventh largest airline in North America by passengers carried. The airline is headquartered in the Long Island City neighborhood of the New York C ...
planned to use offsets for its emissions from domestic flights starting in July 2020, the first major US airline to do so. It also plans to use sustainable aviation fuel made from waste by Finnish refiner Neste
Neste Oyj (international name: Neste Corporation; former names Neste Oil Corporation and Fortum Oil and Gas Oy) is an oil refining and marketing company located in Espoo, Finland. It produces, refines and markets oil products, provides eng ...
starting in mid-2020. In August 2020, JetBlue became entirely carbon-neutral for its U.S. domestic flights, using efficiency improvements and carbon offsets. Delta Air Lines pledged to do the same within ten years.
To become carbon neutral by 2050, United Airlines invests to build in the US the largest carbon capture and storage
Carbon capture and storage (CCS) or carbon capture and sequestration is the process of capturing carbon dioxide (CO2) before it enters the atmosphere, transporting it, and storing it (carbon sequestration) for centuries or millennia. Usually th ...
facility through the company 1PointFive, jointly owned by Occidental Petroleum
Occidental Petroleum Corporation (often abbreviated Oxy in reference to its ticker symbol and logo) is an American company engaged in hydrocarbon exploration in the United States, and the Middle East as well as petrochemical manufacturing in the ...
and Rusheen Capital Management, with Carbon Engineering
Carbon Engineering Ltd. is a Canadian-based clean energy company focusing on the commercialization of Direct Air Capture (DAC) technology that captures carbon dioxide (CO2) directly from the atmosphere.
This captured can either be stored underg ...
technology, aiming for nearly 10% offsets.
See also
References
External links
; Institutional
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{{DEFAULTSORT:Environmental Impact Of Aviation
Aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...
Aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...
Aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...