Situational awareness or situation awareness (SA), knowing what is going on around you, is critical for good decision making in many environments. It is formally defined as: An alternative definition is that situation awareness is adaptive, externally-directed consciousness that has as its products knowledge about a dynamic task environment and directed action within that environment. Situation awareness has been recognized as a critical foundation for successful decision-making across a broad range of situations, many of which involve the protection of human life and property, including law enforcement, aviation, air traffic control, ship navigation, health care, emergency response, military command and control operations, transmission system operators, self defense, and offshore oil and nuclear power plant management. Inadequate situation awareness has been identified as one of the primary causal factors in accidents attributed to human error. The formal definition of SA is often described as three ascending levels: (1) perception of the elements in the environment, (2) comprehension or understanding of the situation, and (3) projection of future status. People with the highest levels of SA have not only perceived the relevant information for their goals and decisions, but are also able to integrate that information to understand its meaning or significance, and are able project likely or possible future scenarios. These higher levels of SA are critical for proactive decision making in demanding environments. Three facets of SA have been the focus in research: SA states, SA systems, and SA processes. SA states refers to the actual level of awareness people have of the situation. SA systems refers to technologies that are developed to support SA in many environments. SA processes refers to the updating of SA states, and what guides the moment-to-moment change of SA. History Although the term itself is fairly recent, the concept has roots in the history of military theory—it is recognizable in Sun Tzu's The Art of War, for example. The term can be traced to World War I, where it was recognized as a crucial skill for crews in military aircraft. There is evidence that the term situational awareness was first employed at the Douglas Aircraft Company during human factors engineering research while developing vertical and horizontal situation displays and evaluating digital-control placement for the next generation of commercial aircraft. Research programs in flight-crew computer interaction and mental workload measurement built on the concept of awareness measurement from a series of experiments that measured contingency