Anaccident is an unintended, normally unwanted event that was not deliberately caused by humans.[1][2] The termaccident implies that the event may have been caused byunrecognized or unaddressed risks. Many researchers, insurers and attorneys who specialize in unintentionalinjury prefer to avoid using the termaccident, and focus on conditions that increase risk of severe injury or that reduce injury incidence and severity.[3] For example, when a tree falls down during awind storm, its fall may not have been directly caused byhuman error, but the tree's type, size, health, location, or improper maintenance may have contributed to the result. Mostcar crashes are the result of dangerous behavior and not purelyaccidents; however, English speakers started using that word in the mid-20th century as a result ofmedia manipulation by the US automobile industry.[4] Accidental deaths were much less frequent before high-powered machinery began to spread with theIndustrial Revolution of the late 1700s.[5]
In recent years worldwide, the most-common causes ofaccidental deaths are road traffic andfalls. Many different theoretical models have been proposed for analyzing accidents, but no single model has yet proved sufficient for these often-complex events.
Physical examples of accidents include unintended motor vehicle collisions, malfunctioning machinery, drowning, falling, or unintentional contact with something sharp or hot or electrified or poisonous (including drug overdoses).
Non-physical examples include unintentionally revealing asecret or otherwise saying something incorrectly, unwittingly deleting electronic data, or forgetting an appointment.
Accidents during the course of work, or arising out of it, are calledwork accidents, occupational accidents, or similar terms. According to theInternational Labour Organization, approximately 400 million accidents happen on the job each year (5% of the world population), causing more than 300,000 deaths annually (especially in mining and construction) and millions of long-termdisabilities (especiallyback injuries).[6][7]
Inprocess manufacturing, a primary accident (such as leakage, fire or explosion) may propagate to nearby units, resulting in an escalating chain of failure, which is often called adomino effect accident.
Commercial products sometimes emerge from accidental discoveries, famously includingpenicillin,Post-it notes, andmicrowave ovens. Injuries that occur during travel to or from employment are sometimes counted statistically as work accidents, but are usually classified separately as transportation accidents instead.
Aviation safety has improved dramatically through decades of concerted effort. Although individual crashes can have high fatality counts and widespread publicity, modern air travel has approximately just 1 fatal crash per 16 million commercial flights (as of 2024), or 1 death per 35 billion passenger-kilometers (22 billion miles), far better than historical rates, and generally the safest way to travel a given distance over land.[8][9] Airplane accidents occur most commonly during the landing process.[10]
Unenclosed two-wheel vehicles are more economical but less visible than the much larger cars and trucks on the road, and bikes offer their riders little protection from collision or weather or hazardous road conditions. For these reasons, bicycle or motorcycle travel typically has multiple times the risk of car travel over a given distance.[11][12]Electric bikes present the further risk of accidental fire from the overheating of their powerful batteries, especially from lower-quality manufacturers.[13]
Water transportation accidents are far too diverse for any simple generalization or statistic. Modernmega-cruise ships are akin to slow-motion cities, where accidental deaths are dwarfed by ordinary heart attacks and strokes.[14] At the opposite extreme of size, technology, and regulation,refugee boats[15] andwhitewater kayaks[16] are much riskier than luxury cruise ships.Ferries overloaded with impoverished crowds capsize regularly,[17] and so do thesailboats of wealthy adventurers,[18] andcargo ships in hazardous waters.[19] Any attempt to summarize maritime accidents would need to recognize all these differences and more.
Road deaths steadily exceed 1 million per year worldwide; more than half are pedestrians, cyclists, or motorcyclists.
Most vehicle collisions are triggered by preventable driver behaviors such asdrunk,drowsy,distracted, ordangerously fast driving, and are not true accidents in the strictest sense. The use of the wordaccident to describe car wrecks was promoted by the USNational Automobile Chamber of Commerce in the middle of the 20th century, as a way to make vehicle-related deaths and injuries seem like an unavoidable matter of fate, rather than a problem that could be addressed byautomotive safety. The automobile industry accomplished this by writing customized articles about local collisions as a free service for newspapers that used the industry's preferred language. Since 1994, the USNational Highway Traffic Safety Administration has asked media and the public not to use the wordaccident to describe vehicle collisions.[4]
For a given distance,passenger trains (and also buses) are considerably safer than car traffic, although riskier than commercial aircraft.[20] Major rail accidents can also arise fromfreight trains, carrying bulk quantities ofhazardous cargo but few people.[21] Unlike most other transportation accidents, a large fraction of train casualties are people out along the route, not riding on the train itself.[22][23]
Rate of accidents requiring medical care, sorted by activity and age (Denmark, 2002)
According to theWorld Health Organization, globally more than 3 millionaccidental deaths occur in a typical year. The most-common causes are road traffic (1.2 million annual deaths, especially for young males) and falls (0.7 million annual deaths, especially for elderly females). Both fatal and nonfatal accident rates in developing countries are at least double the per-capita rates in high-income countries.[24][25]
Many theoretical models to characterize and analyze accidents have been proposed,[29] which can be classified by type. Most accidents have no single cause, and no single model is the sole correct approach for analyzing them.[30] Notable models include:[31]
Sequential models, often depicted asaccident triangles, were proposed for relating the proportions of minor and major incidents. These included Heinrich's triangle (1931)[32] and Frank E. Bird's accident ratio triangle (proposed in 1966 and shown above).
^"Accident".Merriam-Webster Dictionary. Retrieved3 April 2025.1a. an unforeseen and unplanned event or circumstance. 1b. lack of intention or necessity : chance. 2a. an unfortunate event resulting especially from carelessness or ignorance.
^Gabriel, J.M.O.; Nwaeke, L.I.; Amah, E. (April 2019)."Safety Consciousness: An Antidote to Industrial Accidents"(PDF).International Journal of Business and Management Invention. IV.8 (4):1–9.1. a short, sudden and unexpected event or occurrence that results in an unwanted and undesirable outcome ... and must directly or indirectly be the result of human activity rather than a natural event. (Hollnagel, 2004:5). 2. Accidents are the result of technical failures, human errors or organisational problems (Hovden, Albrechtsen and Herrera, 2010:855). 3. An accident as an unplanned and uncontrolled event in which the action or reaction of an object, substance, and person results in personal injury or the productivity thereof (Heinrich, 1959).
^Fiore, David C. (December 2003). "Injuries Associated With Whitewater Rafting and Kayaking".Wilderness and Environmental Medicine.14 (4):255–260.doi:10.1580/1080-6032(2003)14[255:IAWWRA]2.0.CO;2.
^A long list of books and papers is given in:Taylor, G.A.; Easter, K.M.; Hegney, R.P. (2004).Enhancing Occupational Safety and Health. Elsevier. pp. 241–245, see also pp. 140–141,147–153.ISBN0750661976.
^Toft, Yvonne; Dell, Geoff; Klockner, Karen K.; Hutton, Allison (2012)."Models of Causation: Safety"(PDF). In Health and Safety Professionals Alliance (ed.).OHS Body of Knowledge. Safety Institute of Australia.ISBN978-0-9808743-1-0.Archived(PDF) from the original on 25 February 2017.
^Bird, Frank E.; Germain, George L. (1985).Practical Loss Control Leadership. International Loss Control Institute.ISBN978-0880610544.OCLC858460141.
^Gibson, James J. (1961). "The contribution of experimental psychology to the formulation of the problem of safety". In Jacobs, Herbert H. (ed.).Behavioural Approaches to Accident Research.
^Reason, James T. (1991). "Too Little and Too Late: A Commentary on Accident and Incident Reporting". In Van Der Schaaf, T.W.; Lucas, D.A.; Hale, A.R. (eds.).Near Miss Reporting as a Safety Tool. Butterworth-Heinemann. pp. 9–26.
^Benner, Ludwig Jr (June 1975). "Accident Investigations: Multilinear Events Sequencing Methods".Journal of Safety Research.7 (2):67–73.
^Rasmussen, Jens; Jensen, Aage (May 1974). "Mental Procedures in Real-Life Tasks: A Case Study of Electronic Trouble Shooting".Ergonomics.17 (3):293–307.doi:10.1080/00140137408931355.PMID4442376.
