There are numerous definitions that relate to Situation Awareness.
One definition of SA is:
The perception of the elements in the environment within a volume of time and space, the comprehension of their meaning and the projection of their status in the near future.
Another definition is:
Situation awareness relates to one’s ability to accurately perceive what is in the cockpit and outside the aircraft. It is also one’s ability to comprehend the meaning of different elements in the environment and the projection of their status in the near future.
(CAA Document 29).
A third definition is:
Situation awareness refers to one’s ability to accurately perceive what is going on in the cockpit and outside the aircraft. It further extends to the planning of several solutions for any emergency situation which could occur in the immediate future. Maintaining a state of awareness of one’s situation is a complex process, greatly motivated by the understanding that one’s perception of reality sometimes differs from reality itself. This awareness promotes ongoing questioning, cross-checking, and refinement of one’s perception. Constant, conscious monitoring of the situation is required. Note that the situation referred to here includes the human environment. The evaluation of oneself and others for partial or total incapacitation is vital but often overlooked.
(ICAO – HF Digest 2)
Team SA has been defined by Wagner and Simon as:
The crew’s understanding of flight factors that affect (or could affect) the crew and aircraft at any given time.