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The consequences of human failures can be immediate or delayed and the failures can be grouped into the following categories:

Table 4.1 Industrial accidents caused by human error.

Accident, industry and date	consequences	Human contribution and other cause
Union Carbide Bhopal, 1984 (Chemical Unit)	The plant released a cloud of toxic methyl isocyanate. Death toll was 2500 and over one quarter of the city's population was affected by the gas.	The leak was caused by a discharge of water into a storage tank. This was the result of a combination of operator error, poor maintenance, failed safety systems, and poor safety management.
Space Shuttle Challenger 1986 (Aerospace)	An explosion shortly after lift‐off killed all seven astronauts on board	An O‐ring seal on one of the solid rocket boosters split after take‐off releasing a jet of ignited fuel. Inadequate response to internal warnings about the faulty seal design. Decision taken to go for launch in very cold temperature despite faulty seal. Decision‐making result of conflicting scheduling/safety goals, mindset, and effects of fatigue.
Piper Alpha 1988 (Offshore)	167 workers died in the North Sea after a major explosion and fire on an offshore platform	Formal inquiry found a number of technical and organizational failures. Maintenance error that eventually led to the leak was the result of inexperience, poor maintenance procedures, and poor learning by the organization. There was a breakdown in communications and the permit‐to work system at shift changeover, and safety procedures were not practiced sufficiently
Texaco Refinery, 1994 (Petroleum Industry	An explosion on the site was followed by a major hydrocarbon fire and a number of secondary fires. There was severe damage to process plant, buildings and storage tanks. 26 people sustained injuries, none serious.	The incident was caused by inflammable hydrocarbon liquid being continuously pumped into a process vessel that had its outlet closed. This was the result of a combination of: an erroneous control system reading of a valve state, modifications which had not been fully assessed, failure to provide operators with the necessary process overviews and attempts to keep the unit running when it should have been shut down.

Active failures‐ Active failures are the acts or conditions precipitating the incident situation. Active failures have an immediate consequence and are usually made by front‐line people such as drivers, control room staff or machine operators. In a situation where there is no room for error, these active failures have an immediate impact on failure.

Latent failures‐ Though active failures are the acts or conditions precipitating the incident situation. Latent human error is made due to systems or routines that are formed in such a way that humans are disposed to making these errors.