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Air safety is a broad term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through appropriate regulation, as well as through education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel. No matter the speed and economy of any mode of transportation, if it is not perceived and demonstrated as safe, it will find few customers and, with few customers, unless it can still be priced to make a profit, the transportation mode will fail and fade from the scene. The airships of the 1920s and 30sprovide a good example of this principle.
Balanced against the speed of travel and the convenience of schedule, transportation by air must overcome various phobias of much of the traveling public: fear of heights, enclosed spaces, surrender of control. Human phobias are not a factor with cargo shipments, but if the shipment doesn't arrive safely, the airline will find few customers seeking its service.
Air accidents tend to make national, even international, news. In major airliner accidents, hundreds of passengers may be affected. Add to this the number of family members who will be available at the airports at either end of the flight, ready for interviews, providing pictures of anguish on television news and the task before the industry becomes plain.
Therefore, the entire industry and the government bodies who regulate and support it put a great deal of effort into making air transportation not only appear safe, but demonstrating that it is the safest mode of transportation available.
In most countries, civil aircraft have to be certified by the Civil Aviation Authority (CAA) to be allowed to fly. The major aviation authorities worldwide are the US Federal Aviation Administration (FAA) the European Aviation Safety Agency (EASA) (which provides regulatory advice to the European Union and to a degree supplanted the regulatory bodies of member countries) and the Joint Aviation Authorities (JAA) which advises the CAAs that are members of the European Civil Aviation Conference). FAA, EASA and JAA collaborate on many issues, especially in order to provide streamlined procedure and avoid conflicting or duplicate requirements. FAA and EASA are, in particular, primarily responsible for the certification of the airliners from the two major manufacturers, Boeing and Airbus.
Aircraft are certified against standards set out in the code for each CAA. Those codes are very similar and differ primarily in equipment and environmental standards. Regulations on maintenance, repair and operation provide further direction to the owners of the aircraft so that the aircraft continues to meet design standards.
During the 1920s, the first laws were passed in the USA to regulate civil aviation. Of particular significance was the Air Commerce Act 1926 , which required pilots and aircraft to be examined and licensed, for accidents to be properly investigated, and for the establishment of safety rules and navigation aids, under the Aeronautics Branch of the United States Department of Commerce. Despite this, in 1926 and 1927 there were a total of 24 fatal commercial airline crashes, a further 16 in 1928, and 51 in 1929 (killing 61 people), which remains the worst year on record at an accident rate of about 1 for every 1,000,000 miles flown. Based on the current numbers flying, this would equate to 7,000 fatal incidents per year.
The fatal incident rate has declined steadily ever since, and, since 1997 the number of fatal air accidents has been no more than 1 for every 2,000,000,000 person-miles flown (e.g., 100 people flying a plane for 1000 miles counts as 100,000 person-miles, making it comparable with methods of transportation with different numbers of passengers, such as one person driving a car for 100,000 miles, which is also 100,000 person-miles), making it one of the safest modes of transport.
Safety improvements have resulted from a wide variety of factors, including improved aircraft design, engineering and maintenance, the evolution of navigation aids, and safety protocols and procedures.
It is often reported that air travel is the safest in terms of deaths per passenger mile. The National Transportation Safety Board (2006) reports 1.3 deaths per hundred million vehicle miles for travel by car, and 1.7 deaths per hundred million vehicle miles for travel by air. These are not passenger miles. If an airplane has 100 passengers, then the passenger miles are 100 times higher, making the risk 100 times lower. The number of deaths per passenger mile on commercial airlines between 1995 and 2000 is about 3 deaths per 10 billion passenger miles.
One of the first navigation aids to be introduced (in the USA in the late 1920s) was airfield lighting to assist pilots to make landings in poor weather or after dark. The Precision Approach Path Indicator was developed from this in the 1930s, indicating to the pilot the angle of descent to the airfield. This later became adopted internationally through the standards of the International Civil Aviation Organization (ICAO).
With the spread of radio technology, several experimental radio based navigation aids were developed from the late 1920s onwards. These were most successfully used in conjunction with instruments in the cockpit in the form of Instrument landing systems (ILS), first used by a scheduled flight to make a landing in a snowstorm at Pittsburgh in 1938. A form of ILS was adopted by the ICAO for international use in 1949.
Following the development of radar in World War II, it was deployed as a landing aid for civil aviation in the form of Ground Control Approach (GCA) systems, joined in 1948 by Distance measuring equipment (DME), and in the 1950s by airport surveillance radar as an aid to air traffic control. VHF omnidirectional range (VOR) became the predominate means of route navigation during the 1960s superseding the Non-directional beacon (NDB). The ground based VOR stations were often combined with DME at the same site, so that pilots could know both their radials in degrees with respect to north to, and their slant range distance to, that beacon.
All of the ground-based navigation aids are rapidly being supplemented by satellite-based aids like Global Positioning System (GPS), which make it possible for aircrews to know their position with great precision anywhere in the world. With the arrival of Wide Area Augmentation System (WAAS), GPS navigation has become accurate enough for vertical (altitude) as well as horizontal use, and is being used increasingly for instrument approaches as well as en-route navigation. However, since the GPS constellation is a single-point of failure that can be switched off by the U.S. military in time of crisis, ground-based navigation aids are still required for backup.
Air safety topics
Apart from the physical causes of accident
Ice and snow Engine failure Metal fatigue Delamination Stalling Fire Bird strike Ground damage Volcanic ash
See also aviation medicine Human factors including pilot error are another potential danger, and currently the most common factor of aviation crashes. Much progress in applying human factors to improving aviation safety was made around the time of World War II by people such as Paul Fitts and Alphonse Chapanis. However, there has been progress in safety throughout the history of aviation, such as the development of the pilot's checklist in 1937. Pilot error and improper communication are often factors in the collision of aircraft. This can take place in the air (1978 Pacific Southwest Airlines PSA Flight 182|Flight 182]]) or on the ground (1977 Tenerife disaster). The ability of the flight crew to maintain situational awareness is a critical human factor in air safety.
Failure of the pilots to properly monitor the flight instruments resulted in the crash of Eastern Air Lines Flight 40 in 1972, and error during take-off and landing can have catastrophic consequences, for example cause the crash of Prinair Flight 191 on landing, which also in 1972.
Rarely, flight crew members are arrested or subject to disciplinary action for being intoxicated on the job. In 1990, three Northwest Airlines crew members were sentenced to jail for flying from Fargo, North Dakota to Minneapolis-Saint Paul International Airport while drunk. In 2001, Northwest fired a pilot who failed a breathalyzer test after flying from San Antonio, Texas to Minneapolis-Saint Paul. In July 2002, two America West Airlines pilots were arrested just before they were scheduled to fly from Miami, Florida to Phoenix, Arizona because they had been drinking alcohol. The pilots have been fired from America West and the FAA revoked their pilot's licenses. As of 2005 they await trial in a Florida court. The incident created a public relations problem and America West has become the object of many jokes about drunk pilots. While these drunk-flying incidents did not result in crashes, they underscore the role that poor human choices can play in air accidents.
Human factors incidents are not limited to errors by the pilots. The failure to close a cargo door properly on Turkish Airlines Flight 981 in 1974 resulted in the loss of the aircraft - however the design of the cargo door latch was also a major factor in the incident. In the case of Japan Airlines Flight 123, improper maintenance resulted in the loss of the vertical stabilizer.
Controlled flight into terrain (CFIT) is a class of accident in which an undamaged aircraft is flown, under control, into terrain. CFIT accidents typically are a result of pilot error or of navigational system error. Some pilots, convinced that advanced electronic navigation systems such as GPS and inertial guidance systems (inertial navigation system or INS) coupled with flight management system computers , or over-relianced on them, are partially responsible for these accidents, have called CFIT accidents "computerized flight into terrain". Failure to protect Instrument Landing System critical areas can also cause controlled flight into terrain. Crew awareness and monitoring of navigational systems can prevent or eliminate CFIT accidents. Crew Resource Management is a modern method now widely used to improve the human factors of air safety. The Aviation Safety Reporting System, or ASRS is another.
Other technical aids can be used to help pilots maintain situational awareness. A ground proximity warning system is an on-board system that will alert a pilot if the aircraft is about to fly into the ground. Also, air traffic controllers constantly monitor flights from the ground and at airports.
Terrorism can also be considered a human factor. Crews are normally trained to handle hijack situations. Prior to the September 11, 2001 attacks, hijackings involved hostage negotiations. After the September 11, 2001 attacks, stricter airport security measures are in place to prevent terrorism using a Computer Assisted Passenger Prescreening System, Air Marshals, and precautionary policies. In addition, counter-terrorist organizations monitor potential terrorist activity.
Although most air crews are screened for psychological fitness, some may take suicidal actions. In the case of EgyptAir Flight 990, it appears that the first officer (co-pilot) deliberately dove his aircraft into the Atlantic Ocean while the captain was away from his station, in 1999 off Nantucket, Massachusetts. Motivations are unclear, but recorded inputs from the black boxes showed no mechanical problem, no other aircraft in the area, and was corroborated by the cockpit voice recorder.
The use of certain electronic equipment is partially or entirely prohibited as it may interfere with aircraft operation, such as causing compass deviations. Use of personal electronic devices and calculators may be prohibited when an aircraft is taking off or landing. The American Federal Communications Commission (FCC) prohibits the use of a cell phone on most flights, because in-flight usage creates problems with ground-based cells. There is also concern about possible interference with aircraft navigation systems, although that has never been proven to be a non-serious risk on airliners. A few flights now allow use of cell phones, where the aircraft have been specially wired and certified to meet both FAA and FCC regulations.
Airport design and location can have a big impact on air safety, especially since some airports such as Chicago Midway International Airport were originally built for propeller planes and many airports are in congested areas where it is difficult to meet newer safety standards. For instance, the FAA issued rules in 1999 calling for a runway safety area, usually extending Template:Ft to m/dim
to each side and Template:Ft to m/dim beyond the end of a runway. This is intended to cover ninety percent of the cases of an aircraft leaving the runway by providing a buffer space free of obstacles. Since this is a recent rule, many airports do not meet it. One method of substituting for the Template:Ft to m/dim at the end of a runway for airports in congested areas is to install an Engineered materials arrestor system, or EMAS. These systems are usually made of a lightweight, crushable concrete that absorbs the energy of the aircraft to bring it to a rapid stop. They have stopped three aircraft (as of 2005) at JFK Airport.
In considering that on an airplane, hundreds of people sitting in a confined space for extended periods of time should result in the ready transmission of airborne infections should not come as a surprise. For this reason, airlines place restrictions on the travel of passengers with known airborne contagious diseases (e.g. tuberculosis). During the severe acute respiratory syndrome (SARS) epidemic of 2003, awareness of the possibility of acquisition of infection on a commercial aircraft reached it zenith when on one flight from Hong Kong to Beijing, 16 of 120 people on the flight developed proven SARS from a single index case.
There is very limited research (and this has been edited) done on contagious diseases on aircraft. The two most common respiratory pathogens to which air passengers are exposed are parainfluenza and influenza. Certainly, the flight ban imposed following the attacks of September 11, 2001 restricted the ability of influenza to spread around the globe, resulting in a much milder influenza season that year, and the ability of influenza to spread on aircraft has been well documented. There is no data on the relative contributions of large droplets, small particles, close contact, surface contamination, and certainly no data on the relative importance of any of these methods of transmission for specific diseases, and therefore very little information on how to control the risk of infection. There is no standardisation of air handling by aircraft, installation of HEPA filters or of hand washing by air crew, and no published information on the relative efficacy of any of these interventions in reducing the spread of infection.
Air traffic accidents
Accidents and incidents
- Australian Transport Safety Bureau]
- Transportation Safety Board of Canada
- Bureau d'Enquêtes et d'Analyses pour la sécurité de l'Aviation Civile (France)
- Bundesstelle für Flugunfalluntersuchung (Germany)
- Air Accident Investigation Unit (Ireland)
- Aircraft and Railway Accidents Investigation Commission (Japan)
- Air Accidents Investigation Branch (UK)
- National Transportation Safety Board (USA)
- Department of Transport and Regional Services (Australia)
- Transport Canada
- Joint Aviation Authorities (Europe)
- European Aviation Safety Agency
- Irish Aviation Authority
- United Kingdom Civil Aviation Authority
- Federal Aviation Administration (US)
- Federal Aviation Regulations
- Airline complaints
- Aircraft safety card
- Avionics software
- Flight planning
- Hazard analysis
- Human reliability
- In-flight safety demonstration
- JACDEC - Jet Airliner Crash Data Evaluation Centre
- Pilot error
- Road-traffic safety
- Swiss Cheese model of accident causation in human systems
- Transportation safety
- Airdisaster - Database of Airborne Accidents
- Aviation Safety Network
- Flight Safety
- Jet Airliner Crash Data Evaluation Centre
- Air Transportation Safety Resources A recently updated comprehensive and annotated bibliography of books and periodicals designed to aid researchers.
- International Air Transport Association (IATA) Operational Safety Audit (IOSA)
- Aviation Safety: Advancements Being Pursued to Improve Airliner Cabin Occupant Safety and Health, 2003
- International Regulatory & Government Agencies
- Airline Safety.com
- NASA Aviation Safety Reporting System (ASRS)
- The Adolescence of Aviation Psychology
- Aviation Safety Quotations
- Canadian Air Transport Security Authority (CATSA) Official Website
- Accidental Deaths - United States - 1999-2003
- Aircraft Accidents in the United States, 2006
- The VOR
- How the Pilot's Checklist Came About
- U.S. drops prosecution of allegedly tipsy pilots (second story)
- Mangili A, Gendreau MA (2005). Transmission of infectious diseases during commercial air travel. Lancet 365: 989–96. PMID 15767002.
- Leder K, Newman D (2005). Respiratory infections during air travel. Intern Med J 35. PMID 15667469.
- Olsen SJ, Chang HL, Cheung TY, et al. (2003). Transmission of the severe acute respiratory syndrome on aircraft. N Engl J Med 349: 2416–22. PMID 14681507.
- Luna LK, Panning M, Grywna K, Pfefferle S, Drosten C (2007). Spectrum of viruses and atypical bacteria in intercontinental air travelers with symptoms of acute respiratory infection. J Infect Dis 195: 675–9. PMID 17262708.
- Brownstein JS, Wolfe CJ, Mandl KD (2006). Empirical evidence for the effect of airline travel on inter-regional influenza spread in the United States. PLoS Med 3: 3401. PMID 16968115.
- Pavia AT (2007). Germs on a Plane: Aircraft, International Travel, and the Global Spread of Disease. J Infect Dis 195: 621–22.
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