Air safety is a term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.
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 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 (1,600,000 km) 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 1,000 miles (1,600 km) 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 (160,000 km), which is also 100,000 person-miles), making it one of the safest modes of transportation, if measured by distance traveled.
A disproportionate number of all U.S. aircraft crashes occur in Alaska, largely as a result of severe weather conditions. Between 1990-2006 there were 1441 commuter and air taxi crashes in the U.S. of which 373 (26%) were fatal, resulting in 1063 deaths (142 occupational pilot deaths). Alaska accounted for 513 (36%) of the total U.S. crashes.[1]
Another aspect of safety is protection from attack currently known as Security (as the ISO definition of safety encompasses non-intentional (safety_safety) and intentional (safety_security) causes of harm or property damage). The terrorist attacks of 2001 are not counted as accidents. However, even if they were counted as accidents they would have added only about 2 deaths per 2,000,000,000 person-miles. Only 2 months later, American Airlines Flight 587 crashed in Queens, NY, killing 256 people, including 5 on the ground, causing 2001 to show a very high fatality rate. Even so, the rate that year including the attacks (estimated here to be about 4 deaths per 1,000,000,000 person-miles), is safe compared to some other forms of transport, if measured by distance traveled.
Safety improvements have resulted from 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. The number of deaths per passenger mile on commercial airlines in the United States between 1995 and 2000 is about 3 deaths per 10 billion passenger miles.[2]
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).
In 1929 Jimmy Doolittle developed instrument flight.
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-controlled 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) stations became the predominate means of route navigation during the 1960s, superseding the low frequency radio ranges and the Non-directional beacon (NDB). The ground based VOR stations were often co-located with DME transmitters and then labeled as VOR-DME stations on navigation charts. VORTAC stations, which combined VOR and TACAN features (military TACtical Air Navigation) — the latter including both a DME distance feature and a separate TACAN azimuth feature, which provides military pilots data similar to the civilian VOR, were also used in that new system. With the proper receiving equipment in the aircraft, pilots could know their radials in degrees to/from the VOR station, as well as the slant range distance to/from, if the station was co-located with DME or TACAN.[3]
All of the ground-based navigation aids are 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, onboard Inertial Navigation System (INS) or ground-based navigation aids are still required for backup.
Foreign object debris (FOD) includes items left in the aircraft structure during manufacture/repairs, debris on the runway and solids encountered in flight (e.g. hail and dust). Such items can damage engines and other parts of the aircraft. Air France Flight 4590 crashed after hitting a part that had fallen from another aircraft.
A pilot might fly the plane in an accident-prone manner when misinformed by a printed document (manual, map etc.), by reacting to a faulty instrument or indicator (either in cockpit or on ground)[4][5] or by following inaccurate instructions or information from flight or ground control.[6][7][8] Lack of information by the control tower, or delayed instructions, are major factors contributing to accidents.[9]
Boeing studies have shown that airliners are struck by lightning on average of twice per year. While the "flash and bang" is startling to the passengers and crew, aircraft are able to withstand normal lightning strikes.
The dangers of more powerful positive lightning were not understood until the destruction of a glider in 1999.[10] It has since been suggested that positive lightning may have caused the crash of Pan Am Flight 214 in 1963. At that time aircraft were not designed to withstand such strikes, since their existence was unknown at the time standards were set. The 1985 standard in force at the time of the glider crash, Advisory Circular AC 20-53A,[10] was replaced by Advisory Circular AC 20-53B in 2006,[11] however it is unclear whether adequate protection against positive lightning was incorporated.[12][13]
The effects of normal lightning on traditional metal-covered aircraft are well understood and serious damage from a lightning strike on an airplane is rare. However, as more and more aircraft, like the upcoming Boeing 787, whose whole exterior is made of non-conducting composite materials take to the skies, additional design effort and testing must be made before certification authorities will permit these aircraft in commercial service.
Ice and snow can be factors in airline accidents. In 2005, Southwest Airlines Flight 1248 slid off the end of a runway after landing in heavy snow conditions, killing one child.
Even a small amount of icing or coarse frost can greatly impair the ability of a wing to develop adequate lift, which is why regulations prohibit ice, snow or even frost on the wings or tail, prior to takeoff.[14] Air Florida Flight 90 crashed on takeoff in 1982, as a result of ice/snow on its wings.
An accumulation of ice during flight can be catastrophic, as evidenced by the loss of control and subsequent crashes of American Eagle Flight 4184 in 1994, and Comair Flight 3272 in 1997. Both aircraft were turboprop airliners, with straight wings, which tend to be more susceptible to inflight ice accumulation, than are swept-wing jet airliners.[15]
Airlines and airports ensure that aircraft are properly de-iced before takeoff whenever the weather involves icing conditions. Modern airliners are designed to prevent ice buildup on wings, engines, and tails (empennage) by either routing heated air from jet engines through the leading edges of the wing, and inlets[citation needed], or on slower aircraft, by use of inflatable rubber "boots" that expand to break off any accumulated ice.
Airline flight plans require airline dispatch offices to monitor the progress of weather along the routes of their flights, helping the pilots to avoid the worst of inflight icing conditions. Aircraft can also be equipped with an ice detector in order to warn pilots to leave unexpected ice accumulation areas, before the situation becomes critical.[citation needed]
An engine may fail to function because of fuel starvation (e.g. British Airways Flight 38), fuel exhaustion (e.g. Gimli Glider), foreign object damage (e.g. US Airways Flight 1549), mechanical failure due to metal fatigue (e.g. Kegworth air disaster, El Al Flight 1862, China Airlines Flight 358), mechanical failure due to improper maintenance (e.g. American Airlines Flight 191), mechanical failure caused by an original manufacturing defect in the engine (e.g. Qantas Flight 32, United Airlines Flight 232, Delta Air Lines Flight 1288), and pilot error (e.g. Pinnacle Airlines Flight 3701).
In a multi-engine aircraft, failure of a single engine usually results in a precautionary landing being performed, for example landing at a diversion airport instead of continuing to the intended destination. Failure of a second engine (e.g. Dominicana DC-9 air disaster) or damage to other aircraft systems caused by an uncontained engine failure (e.g. United Airlines Flight 232) may, if an emergency landing is not possible, result in the aircraft crashing.
Examples of failure of aircraft structures caused by metal fatigue include the De Havilland Comet accidents (1950s) and Aloha Airlines Flight 243 (1988). Now that the subject is better understood, rigorous inspection and nondestructive testing procedures are in place.
Composite materials consist of layers of fibers embedded in a resin matrix. In some cases, especially when subjected to cyclic stress, the layers of the material separate from each other (delaminate) and lose strength. As the failure develops inside the material, nothing is shown on the surface; instrument methods (often ultrasound-based) have to be used to detect such a material failure. In the 1940s several Yakovlev Yak-9s experienced delamination of plywood in their construction.
Stalling an aircraft (increasing the angle of attack to a point at which the wings fail to produce enough lift), is dangerous and can result in a crash if the pilot fails to quickly react in the proper manner. The only way to recover with a minimum loss of altitude, is to lower the nose (reduces the angle of attack of the wings, so that the boundary layer re-attaches to the wing), while commanding maximum power from the engines. If the pilot delays initiating that kind of response, a crash is inevitable if the plane is not high enough above all terrain, when the stall occurs.
Devices have been developed to warn the pilot when the plane's speed is coming close to the stall speed. These include stall warning horns (now standard on virtually all powered aircraft), stick shakers and voice warnings. Most stalls are a result of the pilot allowing the plane to go too slow for the particular weight and configuration at the time. The stall speed is higher on virtually all aircraft, if ice or even frost has attached to the wings and/or horizontal tail stabilizer. The more severe the icing, the higher will be the stall speed, not only because smooth airflow over the wings becomes increasingly more difficult, but also because of the added weight of the accumulated ice.
"High speed stalls" are also possible, if a pilot tries to pull out of a dive so quickly that he increases the angle of attack to the point of boundary layer separation of the airflow over the wings. Again, the only solution is to lower the nose somewhat, even though the plane is already diving at high speed, and then to resume the pull-out with a less severe angle of attack.
Crashes, caused by a full stall of the airfoils include:
Safety regulations control aircraft materials and the requirements for automated fire safety systems. Usually these requirements take the form of required tests. The tests measure flammability and the toxicity of smoke. When the tests fail, they fail on a prototype in an engineering laboratory, rather than in an aircraft.
Fire on board the aircraft, and more especially the toxic smoke generated, have been the cause of accidents. An electrical fire on Air Canada Flight 797 in 1983 caused the deaths of 23 of the 46 passengers, resulting in the introduction of floor level lighting to assist people to evacuate a smoke-filled aircraft. Two years later a fire on the runway caused the loss of 55 lives, 48 from the effects of incapacitating and subsequently lethal toxic gas and smoke, in the 1985 British Airtours Flight 28M. That accident raised serious concerns relating to survivability, something that prior to 1985 had not been studied in such detail. The swift incursion of the fire into the fuselage and the layout of the aircraft impaired passengers' ability to evacuate, with areas such as the forward galley area becoming a bottle-neck for escaping passengers, with some dying very close to the exits. A large amount of research into evacuation and cabin and seating layouts was carried at Cranfield Institute to try to measure what makes a good evacuation route, which led to the seat layout by Overwing exits being changed by mandate and the examination of evacuation requirements relating to the design of galley areas. The use of smoke hoods or misting systems were also examined although both were rejected.
South African Airways Flight 295 was lost in the Indian Ocean in 1987 after an in-flight fire in the cargo hold could not be suppressed by the crew. The cargo holds of most airliners are now equipped with automated halon fire extinguishing systems to combat a fire that might occur in the baggage holds. In May 1996 ValuJet Airlines Flight 592 crashed into the Florida Everglades a few minutes after takeoff after a fire broke out in the forward cargo hold. All 110 aboard were killed.
At one time fire fighting foam paths were laid down before an emergency landing, but the practice was considered only marginally effective, and concerns about the depletion of fire fighting capability due to pre-foaming led the United States FAA to withdraw its recommendation in 1987.
One possible cause of fires in airplanes are wiring problems that involve intermittent faults, such as wires with breached insulation touching each other, having water dripping on them, or short circuits. These are difficult to detect once the plane is on the ground. However, there are methods, such as spread-spectrum time-domain reflectometry, that can feasibly test live wires on aircraft during flight.[16]
Main article:
Bird strikeBird strike is an aviation term for a collision between a bird and an aircraft. Fatal accidents have been caused by both engine failure following bird ingestion and bird strikes breaking cockpit windshields.
Modern jet engines have the capability of surviving an ingestion of a bird. Small fast planes, such as military jet fighters, are at higher risk than heavy multi-engine ones. This is due to the fact that the fan of a high-bypass turbofan engine, typical on transport aircraft, acts as a centrifugal separator to force ingested materials (birds, ice, etc.) to the outside of the fan's disc. As a result, such materials go through the relatively unobstructed bypass duct, rather than through the core of the engine, which contains the smaller and more delicate compressor blades. Military aircraft designed for high-speed flight typically have pure turbojet, or low-bypass turbofan engines, increasing the risk that ingested materials will get into the core of the engine to cause damage.
The highest risk of the bird strike is during the takeoff and landing, in low altitudes, which is in the vicinity of the airports. Some airports use active countermeasures, ranging from a person with a shotgun through recorded sounds of predators to employing falconers. Poisonous grass can be planted that is not palatable to birds, nor to insects that attract insectivorous birds. Passive countermeasures involve sensible land-use management, avoiding conditions attracting flocks of birds to the area (e.g. landfills). Another tactic found effective is to let the grass at the airfield grow taller (approximately 12 inches (30 cm)) as some species of birds won't land if they cannot see one another.
Aircraft are occasionally damaged by ground equipment at the airport. In the act of servicing the aircraft between flights a great deal of ground equipment must operate in close proximity to the fuselage and wings. Occasionally the aircraft gets bumped or worse.
Damage may be in the form of simple scratches in the paint or small dents in the skin. However, because aircraft structures (including the outer skin) play such a critical role in the safe operation of a flight, all damage is inspected, measured and possibly tested to ensure that any damage is within safe tolerances.[citation needed]
An example of this problem was the depressurization incident on Alaska Airlines Flight 536 in 2005. During ground services a baggage handler hit the side of the aircraft with a tug towing a train of baggage carts. This damaged the metal skin of the aircraft. This damage was not reported and the plane departed. Climbing through 26,000 feet (7,900 m) the damaged section of the skin gave way due to the growing difference in pressure between the inside of the aircraft and the outside air. The cabin depressurized with a bang necessitating a rapid descent back to denser (breathable) air and an emergency landing. Post landing examination of the fuselage revealed a 12 in (30 cm) hole on the right side of the airplane.[17]
Plumes of volcanic ash near active volcanoes can damage propellers, engines and cockpit windows.[18] [19] In 1982, British Airways Flight 9 flew through an ash cloud and temporarily lost power from all four engines.
Prior to 2010 the general approach taken by airspace regulators was that if the ash concentration rose above zero, then the airspace was considered unsafe and was consequently closed.[20] Volcanic Ash Advisory Centers enable liaison between meteorologists, volcanologists, and the aviation industry.[21]
NASA air safety experiment (
CID project). The airplane is a Boeing 720 testing a form of jet fuel, known as "
antimisting kerosene", which formed a difficult-to-ignite gel when agitated violently, as in a crash.
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.[22] Pilot error and improper communication are often factors in the collision of aircraft. This can take place in the air (1978 Pacific Southwest Airlines Flight 182) (TCAS) or on the ground (1977 Tenerife disaster) (RAAS). The ability of the flight crew to maintain situational awareness is a critical human factor in air safety. Human factors training is available to general aviation pilots and called single pilot resource management training.
Failure of the pilots to properly monitor the flight instruments resulted in the crash of Eastern Air Lines Flight 401 in 1972 controlled flight into terrain (CFIT), and error during take-off and landing can have catastrophic consequences, for example cause the crash of Prinair Flight 191 on landing, 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 to Minneapolis while drunk. In 2001, Northwest fired a pilot who failed a breathalyzer test after a flight. In July 2002, two America West Airlines pilots were arrested just before they were scheduled to fly 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.[23] The incident created a public relations problem and America West has become the object of many jokes about drunk pilots. At least one fatal airliner accident involving drunk pilots has occurred when Aero Flight 311 crashed killing all 25 on board in 1961, which underscores 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 accident. In the case of Japan Airlines Flight 123, improper maintenance led to explosive decompression of the cabin, which in turn destroyed the vertical stabilizer and the integrity of all four hydraulic systems, which powered all the flight controls.
Controlled flight into terrain is a class of accident in which an aircraft is flown, under control, into terrain or man-made structures. CFIT accidents typically are a result of pilot error or of navigational system error. Failure to protect Instrument Landing System critical areas can also cause CFIT accidents. One of the most notable CFIT accidents was in December 1995 in which American Airlines flight 965 tracked off course while approaching Calí, Colombia and hit a mountainside despite a ground proximity warning system terrain warning in the cockpit and desperate pilot attempt to gain altitude after that warning. Crew position awareness and monitoring of navigational systems are essential to the prevention of CFIT accidents. As of February, 2008, over 40,000 aircraft had the Enhanced version of the GPWS system installed, and they had flown over 800 million hours without a single CFIT accident.[24]
Another anti-CFIT tool is the Minimum Safe Altitude Warning (MSAW) system available near many airports. It monitors the altitudes transmitted by aircraft transponders and compares that with the system's defined minimum safe altitudes for a given area. When the system determines the aircraft is lower, or will soon be lower, than the minimum safe altitude (MSA), the air traffic controller receives an acoustic and visual warning and then alerts the pilot that his aircraft is too low.[25]
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 below 10,000', 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.[citation needed] There is also concern about possible interference with aircraft navigation systems, and has yet to be proven 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.
Main article:
Runway safetyTypes of runway safety incidents include:
- Runway excursion - an incident involving only a single aircraft, where it makes an inappropriate exit from the runway.
- Runway overrun - a type of excursion where the aircraft is unable to stop before the end of the runway (e.g. Air France Flight 358).
- Runway incursion - an incident involving incorrect presence of a vehicle, person or another aircraft on the runway (e.g. Tenerife disaster).
- Runway confusion - an aircraft uses the wrong runway for landing or take-off (e.g. Comair Flight 191).
Aircrew are normally trained to handle hijack situations.[citation needed] Since the September 11, 2001 attacks, stricter airport and airline security measures are in place to prevent terrorism.
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 deliberately dived 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.
In 1982, Japan Airlines Flight 350 crashed while on approach to the Tokyo Haneda Airport, killing 24 of the 174 onboard. The official investigation found the mentally ill captain had attempted suicide by placing the inboard engines into reverse thrust, while the plane was close to the runway. The first officer did not have enough time to countermand his actions, before the plane stalled and crashed.
In 1997, SilkAir Flight 185 suddenly went into a high dive from its cruising altitude. The speed of the dive was so high that the plane began to break apart before it finally crashed near Palembang, Sumatra. After three years of investigation, the Indonesian authorities declared that the cause of the accident can not be determined. However, the US NTSB concluded that deliberate suicide by the Captain, was the only reasonable explanation for the cause of that crash.
Aircraft, whether passenger planes or military aircraft, are sometimes attacked in both peacetime and war. Examples of this include:
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 500 feet (150 m) to each side and 1,000 feet (300 m) 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 1,000 feet (300 m) 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.
According to a 2000 report by the National Transportation Safety Board, emergency aircraft evacuations happen about once every 11 days in the U.S. While some situations are extremely dire, such as when the plane is on fire, in many cases the greatest challenge for passengers can be the use of the airplane slide. In a TIME article on the subject, Amanda Ripley reported that when a new supersized Airbus A380 underwent mandatory evacuation tests in 2006, 33 of the 873 evacuating volunteers got hurt. While the evacuation was generally considered a success, one volunteer suffered a broken leg, while the remaining 32 received slide burns. Such accidents are common. In her article, Ripley provides tips on how to make it down the airplane slide without injury.[26]
There are three main statistics which may be used to compare the safety of various forms of travel:[better source needed][27]
It is necessary to mention that first two statistics are computed for typical travels for respective forms of transport, so they cannot be used directly to compare risks related to different forms of transport in a particular travel "from A to B". For example: according to statistics, a typical flight from Los Angeles to New York will carry a larger risk factor than a typical car travel from home to office. But a car travel from Los Angeles to New York would not be typical. It would be as large as several dozens of typical car travels, and associated risk will be larger as well. Because the journey would take a much longer time, the overall risk associated by making this journey by car will be higher than making the same journey by air, even if each individual hour of car travel can be less risky than an hour of flight. In the same vein, when considering the "deaths per billion passenger journeys" statistic, it is important to consider that airliners, buses and trains will carry far more passengers than a car, or bicycle for example.
It is therefore important to use each statistic in a proper context. When it comes to a question about risks associated with a particular long-range travel from one city to another, the most suitable statistic is the third one, thus giving a reason to name air travel as the safest form of long-range transportation.
It is worth noting that the air industry's insurers base their calculations on the deaths per journey statistic while the industry itself generally uses the deaths per kilometre statistic in press releases.[28]
The Safety Improvement Initiatives are aviation safety partnerships between regulators, manufacturers, operators and professional unions, research organisations, international organisations to further enhance safety. The major Safety initiatives worldwide are:
- Commercial Aviation Safety Team (CAST) in the US. The Commercial Aviation Safety Team (CAST) was founded in 1998 with a goal to reduce the commercial aviation fatality rate in the United States by 80 percent by 2007.
- European Strategic Safety Initiative (ESSI) . The European Strategic Safety Initiative (ESSI) is an aviation safety partnership between EASA, other regulators and the industry. The initiative objective is to further enhance safety for citizens in Europe and worldwide through safety analysis, implementation of cost effective action plans, and coordination with other safety initiatives worldwide.
- ^ "NIOSH Commercial Aviation in Alaska". United States National Institute for Occupational Safety and Health. http://www.cdc.gov/niosh/topics/aviation/. Retrieved 2007-10-15.
- ^ Aircraft Accidents in the United States, 2006
- ^ The VOR
- ^ Haaretz.com: Two planes nearly crash at Ben Gurion Airport due to glitch
- ^ Jerusalem Post: Weeds blamed for spate of near-misses at Ben-Gurion Airport
- ^ momento24.com: An error in the control tower almost caused two planes to collide
- ^ ABC local: NTSB, FAA investigate near-miss mid-air collision
- ^ New York Times: La Guardia Near-Crash Is One of a Rising Number
- ^ BFU-WEB.de: Investigation Report on crash near Ueberlingen
- ^ a b Schleicher ASK 21 two seat glider
- ^ FAA Advisory Circulars
- ^ Hiding requirements = suspicion they're inadequate, Nolan Law Group, January 18, 2010
- ^ A Proposed Addition to the Lightning Environment Standards Applicable to Aircraft, J. Anderson Plumer Lightning Technologies, Inc, published 2005-09-27
- ^ FAA Chapter 27
- ^ airlinesafety.com - Letters to the Editor
- ^ Smith, Paul, Cynthia Furse and Jacob Gunther (Dec 2005). "Analysis of Spread Spectrum Time Domain Reflectometry for Wire Fault Location.". IEEE Sensors Journal 5 (6). http://livewiretest.com/analysis-of-spread-spectrum-time-domain-reflectometry-for-wire-fault-location/.
- ^ National Transportation Safety Board -- Aviation Accidents: SEA06LA033. National Transportation Safety Board. 2006-08-29. http://www.ntsb.gov/ntsb/brief.asp?ev_id=20051229X02026&key=1. Retrieved 2007-07-14
- ^ Danger to Aircraft from Volcanic Eruption Clouds
- ^ Guidance for Flight Crews and Controllers
- ^ http://www.newscientist.com/article/dn18797-can-we-fly-safely-through-volcanic-ash.html
- ^ Volcanic Ash–Danger to Aircraft in the North Pacific
- ^ How the Pilot's Checklist Came About
- ^ U.S. drops prosecution of allegedly tipsy pilots (second story)
- ^ EGPWS
- ^ ATC MSAW system
- ^ How to Escape Down an Airplane Slide - and Still Make Your Connection! Amanda Ripley. TIME. January 23, 2008.
- ^ Informed Sources Archive Alycidon Rail web site. Retrieved 29 April 2009. The site cites the source as an October 2000 article by Roger Ford in the magazine Modern Railways and based on a DETR survey.
- ^ Flight into danger - 07 August 1999 - New Scientist Space
