Aircraft noise pollution
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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 disorders.[1][2][3] Governments have enacted extensive controls that apply to aircraft designers, manufacturers, and operators, resulting in improved procedures and cuts in pollution.
Sound production is divided into three categories:
- Mechanical noise—rotation of the engine parts, most noticeable when fan blades reach supersonic speeds.
- Aerodynamic noise—from the airflow around the surfaces of the aircraft, especially when flying low at high speeds.
- Noise from aircraft systems—cockpit, cabin pressurization, conditioning systems, and Auxiliary Power units.
Mechanisms of sound production
Aircraft noise is
- Engine and other mechanical noise
- Aerodynamic noise
- Noise from aircraft systems
Engine and other mechanical noise
Much of the noise in propeller aircraft comes equally from the propellers and aerodynamics. Helicopter noise is aerodynamically induced noise from the main and tail rotors and mechanically induced noise from the main gearbox and various transmission chains. The mechanical sources produce narrow band high intensity peaks relating to the rotational speed and movement of the moving parts. In
Aircraft gas turbine engines (jet engines) are responsible for much of the aircraft noise during takeoff and climb, such as the buzzsaw noise generated when the tips of the fan blades reach supersonic speeds. However, with advances in noise reduction technologies—the airframe is typically more noisy during landing.[citation needed]
The majority of engine noise heard is due to jet noise—although high bypass-ratio turbofans do have considerable fan noise. The high velocity jet leaving the back of the engine has an inherent shear layer instability (if not thick enough) and rolls up into ring vortices. This later breaks down into turbulence. The SPL associated with engine noise is proportional to the jet speed (to a high power). Therefore, even modest reductions in exhaust velocity will produce a large reduction in jet noise.[citation needed]
Engines are the main source of aircraft noise.
Aerodynamic noise
Aerodynamic noise arises from the airflow around the aircraft
The shape of the nose, windshield or
Typically noise is generated when flow passes an object on the aircraft, for example, the wings or landing gear. There are broadly two main types of airframe noise:
- Bluff Body Noise – the alternating vortex shedding from either side of a bluff body, creates low-pressure regions (at the core of the shed vortices) which manifest themselves as pressure waves (or sound). The separated flow around the bluff body is quite unstable, and the flow "rolls up" into ring vortices—which later break down into turbulence.[5]
- Edge Noise – when turbulent flow passes the end of an object or gaps in a structure (high lift device clearance gaps) the associated fluctuations in pressure are heard as the sound propagates from the edge of the object (radially downwards).[5]
Noise from aircraft systems
Health effects
Aircraft engines are the major source of noise and can exceed 140 decibels (dB) during takeoff. While airborne, the main sources of noise are the engines and the high speed turbulence over the fuselage.[6]
There are
German environmental study
A large-scale statistical analysis of the health effects of aircraft noise was undertaken in the late 2000s by Bernhard Greiser for the Umweltbundesamt, Germany's central environmental office. The health data of over one million residents around the Cologne airport were analysed for health effects correlating with aircraft noise. The results were then corrected for other noise influences in the residential areas, and for socioeconomic factors, to reduce possible skewing of the data.[14]
The German study concluded that aircraft noise clearly and significantly impairs health.
FAA advice
The Federal Aviation Administration (FAA) regulates the maximum noise level that individual civil aircraft can emit through requiring aircraft to meet certain noise certification standards. These standards designate changes in maximum noise level requirements by "stage" designation. The U.S. noise standards are defined in the Code of Federal Regulations (CFR) Title 14 Part 36 – Noise Standards: Aircraft Type and Airworthiness Certification (14 CFR Part 36). The FAA says that a maximum day-night average sound level of 65 dB is incompatible with residential communities.[15] Communities in affected areas may be eligible for mitigation such as soundproofing.
Cabin noise
Aircraft noise also affects people within the aircraft: crew and passengers. Cabin noise can be studied to address the
Cognitive effects
Simulated aircraft noise at 65 dB(A) has been shown to negatively affect individuals’ memory and recall of auditory information.[21] In one study comparing the effect of aircraft noise to the effect of alcohol on cognitive performance, it was found that simulated aircraft noise at 65 dB(A) had the same effect on individuals’ ability to recall auditory information as being intoxicated with a Blood Alcohol Concentration (BAC) level of at 0.10.[22] A BAC of 0.10 is double the legal limit required to operate a motor vehicle in many developed countries such as Australia.
Mitigation programs
In the United States, since aviation noise became a public issue in the late 1960s, governments have enacted legislative controls. Aircraft designers, manufacturers, and operators have developed quieter aircraft and better operating procedures. Modern high-bypass turbofan engines, for example, are notably more quiet than the turbojets and low-bypass turbofans of the 1960s. FAA Aircraft Certification achieved noise reductions classified as "Stage 3" aircraft; which has been upgraded to "Stage 4" noise certification resulting in quieter aircraft. This has resulted in lower noise exposures in spite of increased traffic growth and popularity.[23]
In the 1980s, the
Regulation
Stages are defined in the US Code of Federal Regulations (CFR) Title 14 Part 36.[25] For civil
The US allows both the louder Stage 1 and quiet Stage 2 helicopters.[26] The quietest Stage 3 helicopter noise standard became effective on May 5, 2014, and are consistent with ICAO Chapter 8 and Chapter 11.[25]
Chapter | Year | Ch. 3 Margin | Types[28] |
---|---|---|---|
none | before | none | Boeing 707, Douglas DC-8 |
2 | 1972 | ~+16 dB | Boeing 727, McDonnell Douglas DC-9 |
3 | 1978 | baseline | MD-80
|
4 (stage 4) | 2006 | −10 dB | Boeing 737NG, Boeing 767, Boeing 747-400
|
14 (stage 5) | 2017–2020 | −17 dB | Boeing 787
|
Night flying restrictions
At
Usage of satellite-based navigation systems can contribute to noise relief, trials in 2013-14 found, though results were not always beneficial due to concentrating flight paths. Changing flight angles and flight paths brought some changes in noise relief for some local people.
Technological advances
Engine design
Modern
Engine location
The ability to reduce noise may be limited if engines remain below aircraft's wings. NASA expects a cumulative 20–30 dB below Stage 4 limits by 2026–2031, but keeping aircraft noise within
By 2020,
See also
- Aviation taxation and subsidies
- Electric airplane
- Farley v Skinner
- Hush kit
- Helicopter noise reduction
- Jet noise
- Noise barrier
- Rotor-stator interaction
- Silent Aircraft Initiative
- Toroidal propeller
- Train noise
- XF-84H Thunderscreech, the loudest aircraft ever built.
General:
- Health effects from noise
- Noise pollution
- Noise regulation
- Aviation and the environment
References
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- PMID 29538344.
- PMID 30081458.
- ^ a b c Bernie Baldwin (December 18, 2017). "How Crossover Jets Are Meeting The Noise Challenge". Aviation Week & Space Technology.
- ^ a b "Aircraft Airframe Noise—Research Overview". Archived from the original on May 17, 2008. Retrieved July 13, 2008.
- ^ NIOSH (May 9, 2017). "AIRCREW SAFETY & HEALTH". Retrieved June 29, 2018.
- PMID 30505645.
- PMID 2210099.
- ^ Schmid, RE (February 18, 2007). "Aging nation faces growing hearing loss". CBS News. Archived from the original on November 15, 2007. Retrieved February 18, 2007.
- ^ Senate Public Works Committee, Noise Pollution and Abatement Act of 1972, S. Rep. No. 1160, 92nd Cong. 2nd session
- ISBN 978-0-12-427455-6.
- ^ "Analysis | Where noisy roads and airports take the biggest toll on our health and sanity". Washington Post. Retrieved May 20, 2017.
- S2CID 11335200.
- ^ Spiegel, Nr. 51, 14 Dezember 2009, Page 45 (in German)
- ^ "Noise Monitoring". Massport. Archived from the original on February 1, 2014. Retrieved January 31, 2014.
- S2CID 24928181.
- ^ NIOSH (1999). "Health Hazard Evaluation report: Continental Express Airlines, Newark, New Jersey" (PDF). Retrieved June 29, 2018.
- ^ Ozcan HK; Nemlioglu S (2006). "In-cabin noise levels during commercial aircraft flights". Canadian Acoustics. 34 (4).
- S2CID 29612085.
- S2CID 3917183.
- ^ Molesworth BR, Burgess M. (2013). Improving intelligibility at a safety critical point: In flight cabin safety. Safety Science, 51, 11–16.
- ^ Molesworth BR, Burgess M, Gunnell B. (2013). Using the effect of alcohol as a comparison to illustrate the detrimental effects of noise on performance. Noise & Health, 15, 367–373.
- ^ "Stage 4 Aircraft Noise Standards". Rgl.faa.gov. Retrieved September 28, 2012.
- ^ Hogan, C. Michael and Jorgen Ravnkilde, Design of acoustical insulation for existing residences in the vicinity of San Jose Municipal Airport, 1 January 1984, FAA grant-funded research, ISBN B0007B2OG0
- ^ a b c d "Details on FAA Noise Levels, Stages, and Phaseouts". FAA.
- ^ a b c "Aircraft Noise Issues". FAA.
- ^ "Reduction of Noise at Source". ICAO.
- ^ "Airport Charges for Quieter Aircraft" (PDF). Gatwick Airport Community Group. October 20, 2016.
- ^ Dept for Transport (June 2006). "Night flying restrictions at Heathrow, Gatwick and Stansted Airports". Archived from the original on July 17, 2007. Retrieved July 12, 2008.
- ^ Dept for Transport (n.d.). "Night restrictions at Heathrow, Gatwick and Stansted (second stage consultation)". Retrieved July 12, 2008.
- ^ "Modernising UK airspace". heathrow.com. Retrieved September 24, 2015.
- ^ Anderson Acoustics, Westerly And Easterly Departure Trials 2014 - Noise Analysis & Community Response Archived October 28, 2016, at the Wayback Machine, retrieved 29 November 2017
- ^ Zaman, K.B.M.Q.; Bridges, J. E.; Huff, D. L. "Evolution from 'Tabs' to 'Chevron Technology'–a Review" (PDF). Proceedings of the 13th Asian Congress of Fluid Mechanics 17–21 December 2010, Dhaka, Bangladesh. Archived from the original (PDF) on November 20, 2012.
- ^ a b c d e Graham Warwick (May 6, 2016). "Problems Aerospace Still Has To Solve". Aviation Week & Space Technology. Archived from the original on January 2, 2018. Retrieved January 2, 2018.
- U.S. Noise Control Act of 1972 United States Code Citation: 42 U.S.C. 4901 to 4918
- S. Rosen and P. Olin, coronary heart disease, Archives of Otolaryngology, 82:236 (1965)
External links
- "Airbus Noise Technology Centre". University of Southampton, UK.
- "certification noise levels". EASA.
- "Federal Interagency Committee on Aviation Noise (FICAN), US".
- "Aviation Environment Federation (AEF), United Kingdom NGO".
- "Airport Noise Report".
the only newsletter published exclusively for those interested in the complex topic of aircraft noise
- "National Organization to Insure a Sound-controlled Environment(NOISE), US".
- "NASA research on noise-abatement approach profiles for multiengine jet transport aircraft" (PDF). Langley Research Center. June 1967.
- "Getting to grips with aircraft noise" (PDF). Airbus. December 2003.
- "The Silent Aircraft Initiative". Cambridge-MIT Institute. 2006.
- "Attitudes to Noise from Aviation Sources in England (ANASE" (PDF). Department for Transport. October 2007. Archived from the original (PDF) on December 4, 2009. Retrieved June 10, 2020.
- Helmut H. Toebben; et al. (September 2012). "Flight testing of noise abating RNP procedures and steep approaches" (PDF). 28th Congress of the International Council of the Aeronautical Sciences. DLR German Aerospace Center.
- "Check this groovy way to cut out airport noise". Wired UK. July 3, 2014.
- Guy Norris and Graham Warwick (June 19, 2018). "NASA Completes Gear And Flap Noise-Reduction Flights". Aviation Week & Space Technology.