Aircraft LTO emissions contribute to ambient pollutant concentrations and are quantified in local and regional emissions inventories (Ratliff et al., 2009)." Local air quality is an important issue that has to be addressed because it can have a negative impact on the health of people that live in the community. For instance, conditions such as asthma can be irritated by air quality. With this understood, reducing emissions must be a top priority in the aviation industry. In addition locales that are close to commercial and private airports are also susceptible to noise impacts which can significantly jeopardize the quality of life for people who live in these communities. The decibel levels caused by airplanes taking off and landing can be detrimental to hearing especially in young children. In addition the noise created by aircraft can have non-auditory effects on health including sleep disruption. According to Stansfeld & Matheson (2003)

"Noise exposure causes a number of predictable short-term physiological responses mediated through the autonomic nervous system. Exposure to noise causes physiological activation including increase in heart rate and blood pressure, peripheral vasoconstriction and thus increased peripheral vascular resistance…the strongest evidence for the effect of noise on the cardiovascular system comes from studies of blood pressure in occupational settings. Many occupational studies have suggested that individuals chronically exposed to continuous noise at levels of at least 85 dB have higher blood pressure than those not exposed to noise (Stansfeld & Matheson 2003)."

This type of pollution has been debated for many years, particularly as it pertains to the noise produced by certain types of aircraft such as military jets. These types of aircraft have been under great scrutiny for the amount of air pollution that they produce and the amount of hours each day that those particular aircraft operate and how disruptive the noise they produce can be to the daily lives of people living in communities where such noises are prevalent.

Solutions

Beyond the issue of reducing greenhouse gases there are other environmental concerns that impact the air industry. These issues demand 21st century solutions. According to the Air Transport Association the aviation industry must take advantage of new technologies and new ideas if the industry is to be successful at reducing admissions. One such strategy is known as NextGen. NextGen is a term and program designed by the FAA for the purpose of modernizing air traffic control by 2025 ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions"). The program estimates that this modernization will cost a total of $40 billion ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions"). The purpose of the program is to replace the traditional ground-based traffic navigation and surveillance with satellite-based system to more adequately meet the needs of the air industry. The main purpose of NextGen is the En Route Automation Modernization (ERAM) initiative created by the FAA. This initiative provides the groundwork associated with modernizing the en route ATM automation system ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions"). Reformulating the current system is an important aspect of addressing the environmental issues in the aviation industry because

"Today's antiquated ground-based systems add flight time because they do not route aircraft in a direct, linear fashion. Further, because today's technology does not precisely pinpoint an aircraft's position in space, a greater amount of time and separation must be factored in spacing flights apart. Utilizing satellite-based systems, the FAA and airlines will be able to route flights more efficiently, precisely, and directly. This reduces flight miles, flight times, congestion, and delays. Less aircraft time in the air and on the ground means significantly lower fuel consumption and GHG emissions ("21st Century Aviation - a Commitment to Technology, Energy and Climate...

The estimates for such reductions span a range from 6 to 15% ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions").
There are several characteristics associated with NextGen. These characteristics include the following:

1. Automatic Dependent Surveillance-Broadcast (ADS-B) -- these is designed to supply surveillance through the use of space-based GPS. This GPS is utilized to determine the location of aircraft in the same way that traditional ground-based radar has done. This type of surveillance also offers coverage that is similar to that of a radar in locations where coverage is not currently present. Preferably, this type of surveillance will allow a reduction in separation between aircraft because of enhanced precision by allowing the FAA ATC to use shared information between air traffic controllers and pilots ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions").

2. Required Area Navigation (RNAV) -- this characteristic allows aircraft to fly using any path that is covered by ground- or space-based navigation tools. This allows more access to point-to-point functions of the aircraft ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions").

3. Required Navigation Performance (RNP) procedures (RNAV with onboard technology) -- designed to observe aircraft performance and facilitates closer en route spacing without intervention by Air Traffic Controllers. This procedure also leads to more fixed departures/arrivals times ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions").

4. Continuous Descent Arrivals (CDA) -- This characteristic permits the aircraft to operate continuous descent airport approaches as opposed to the conventional "step downs,." This continuous descent tactic leads to the conservation of fuel. When implementing this characteristic it is important to make sure the use of CDA does not have an adverse impact on the efficiency gains made in other areas ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions").

5. Tailored Arrivals -- this characteristic permits aircraft to fly an approach consistent with the conditions on the ground and in the air. In addition the article explains that guidance is created by Air Traffic Control "based on all known constraints and up-linked to aircraft before top-of-descent ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions")."

6. Ground-Based Augmentation System (GBAS) -- this technology is designed to support accurate landings during times of low visibility and inclement weather. This technology also replaces obsolete instrument landing systems (ILS) and has the ability to serve multiple runways at a lower cost and with higher reliability ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions").

7. Precision Runway Monitor-Alternate (PRM-a) -- this is designed to leverage Airport Surface Detection Equipment (ASDE-X) to supply Closely Spaced Parallel Approach abilities at airports. These capabilities permit planes to land in a way that is safe and efficient which increases the capacity of the runway ("21st Century Aviation - a Commitment to Technology, Energy and Climate Solutions").

All of these solutions are needed and consistent with the idea that 21st century technology and know-how can assist greatly in making the air transport industry more environmentally friendly. The NextGen project is unique because it provides solutions that are specifically geared towards change the airline industry using 21st century ideas.

Solutions for improving Air quality and noise pollution

Along with other organizations CATE has developed methods of dealing with the issue of air quality. For instance

"CATE has expertise in air quality modelling and monitoring and provides advice on how emissions can be managed and reduced. Its research programme includes investigation of some of the fundamental processes that control dispersion of pollutants around airports. A recent EPSRC (Engineering and Physical Sciences Research Council) grant has enabled CATE to examine the impact of wing tip induced vortices on the dispersion of aircraft engine exhaust plumes. The Group is leading one of the three recently-established Air Quality Panels for the UK Department of Transport, and contributing to another in order to review the impact of airport related emissions on air quality around Heathrow Airport ("Centre for Air Transport and the Environment (CATE)")."

The model created by CATE will play an instrumental role in ensuring that air quality will improve. Airlines must also take responsibility for the type of pollution that they produce and find ways to reduce this pollution.

As it relates to noise pollution the solutions are a bit more complicated. The complications lie in the fact that airports are often built in rural areas but over time populations grow and begin to encroach upon the areas around the airports. Although there are laws that prohibit the building of houses and businesses within a certain number of miles of an airport, these things can still be built relatively close to the airport. Once populations begin to grow, controlling the noise is all but impossible because it is extremely difficult to move an airport. With this understood makers of aircraft must find ways to make airplanes quieter so that noise pollution is not an issue. Over the years many airplanes have gotten quieter but such changes have been…