Situational Awareness


Situational awareness (SA) simply refers to being aware of your surroundings.

A more general definition describes Situational Awareness as ‘the perception of the elements in the environment within a volume of time and space, comprehension of their meaning and the projection of their status in the near future’(Endsley, 1987 2,1988 3).

Theoretical frame

Situational awareness is a different and separate concept when compared against decision making. It is possible for operators to have clear and accurate situational awareness including perception, comprehension, and prediction, yet make incorrect decisions. Through this it is clear, although situational awareness plays a crucial and important role with decision making, other factors such as experience and training alter the outcome of a situation.

A Theoretical Model of Situational Awareness

To expand on Endsley's definition of SA, the SA construct can be described in three hierarchical phases (Endsley, 1995a 4, 1995b 5).


(Situation Awareness in dynamic decision making, Endsley, 1995b 5. Figure adopted from Wikipedia, 2008 11)

Level 1 SA - Perception of the elements in the environment.
Perception is the fundamental basis and crucial key factor involved in formation of Situational Awareness. It is clear without accurate perception is impossible to achieve correct awareness of situations, this decisions making based on this would be inaccurate.

Level 2 SA - Comprehension of the current situation.
Level two involves the ability to comprehend relevant information, and also build upon level one Situational Awareness of accurate perception. Thus an individual who performs level two, situational awareness is able to derive operationally relevant meaning and significant from level one situational awareness, and comprehend the information.

Level 3 SA - Projection of future status.
Level three situational awareness is built upon the foundations of accurate perception from level one situational awareness, and of efficient and effective comprehension of level two situational awareness. The third level of situational awareness involves the ability to perform future prediction and projection of the given situation and surrounding environment.

A critical part of situational awareness is the ability to understand how much time is available. Until some event occurs or intervention is necessary.

Situational Awareness in Aviation

Fully understanding SA in the aviation situation depends on a clear elucidation of its elements (at each of the three levels of SA), identifying which things the aircrew needs to perceive, understand and project in flight.

Within the various types of aircraft systems, certain types of elements are essential for SA such as:
I. Geographical SA
II. Spartial / temporal system SA
III. System SA
IV. Environmental SA
V. Tactical SA

Individual Factors Influencing SA

SA in the aviation situation is challenged by the limitations of human attention and working memory.

  • Processing limitations

 Attention – direct attention is required for perceiving and processing the environment to form SA for selecting actions and executing responses.

 Working memory – when lacking of other mechanisms, most of a person’s active processing of information must occur in working memory.

  • Coping mechanisms

 - Mental models
 - Goal driven processing
 - Automaticity

SA can be achieved by drawing on a number of internal mechanisms. Due to limitations of attention and working memory, long term memory may be heavily relied on to achieve SA in the highly demanding aviation environment.

Challenges to SA

Many environmental and systematic factors all have huge impacts on SA. Each of these factors can act to seriously challenge the ability of the aircrew to maintain a high level of SA.

  • Stress

A positive amount of stress may actually improve performance by increasing attention to important aspects of the situation. Stressors can affect SA in a number of different ways, including attention narrow, reduction in information intake and reductions in working memory capacity. Several authors have also establish that scanning of information under stress is scattered and poorly organised (Keinan, 1987; Keinan & Friedland, 1987; Wachtel, 1967).

  • Overload / Underload

If the volume of information and number of tasks are enormous, SA may suffer as only a subset of information can be attended to, or the pilot may be actively working to achieve SA, yet suffers from erroneous or incomplete perception and integration of information.

  • System design

The capabilities of the aircraft for acquiring needed information and the way in which it presents that information will have a large impact on aircrew SA.

  • Complexity

System complexity can negatively affect both pilot workload and SA through and increase in the number of systems components to be managed, a high degree of interaction between these components and an increase in the dynamics or rate of change of the components.

  • Automation

SA may also be negatively impacted by the automation of tasks as it is frequently designed to put the aircrew “out of the loop”. SA may not suffer under all forms of automation however Weiner (1993) and Billings (1991) stated that SA may be improved by systems that provide integrated information through automation.

Errors in SA

I. Level 1 – fatigue to correctly perceive the situation
II. Level 2 – failure to comprehend the situation
III. Level 3 – failure to project situation in the future

SA in Multi Crew Aircraft

Team SA has been defined as the degree to which every team member possesses the SA required for his or her responsibilities (Endsley, 1989). By providing shared SA can be greatly enhanced by shared mental models, which provide a common frame of reference for crew member’s action and allow team members to predict each others behaviour (Cannon-Bowers, Salas & Converse, 1993; Orasamu, 1990).

Impact of CRM on SA

CRM can have an effect on crew SA by directly improving SA or indirectly through the advancement of shared mentor models and by providing efficient distribution of attention across the crew.

 Individual SA
 Shared mental models
 Attention distribution

Future Directions

  • Design

Cockpit design advancement can be directed towards several avenues for improving SA, including searching for

a) ways to determine and effectively deliver critical cues
b) ways to ensure accurate expectation
c) methods for assisting pilots in deploying attention effectively
d) Methods for preventing the disruption of attention.
e) Ways to develop systems that are compatible with pilot goals

  • Training

The potential roles of CRM programmes are the answer for improvements in SA. It may also be achievable to create “SA oriented” training programmes that seek to improve SA directly. This may include programs that provide aircrew with better information needed to develop mental models, including information on their components, the dynamics and function of the components, projection of the future action based on these dynamics.

Measurement of Situational Awareness (Endsley, 1995a 4)

In any design process, the use of iterative, manned simulation testing to evaluate competing design concepts is needed in order to detect problems with given designs and to ascertain the best of competing concepts. Several different methods have been attempted or can be considered for the measurement of SA during this type of testing.

Physiological Techniques

Ideally, it would be desirable to install a window on the operator’s mind and observe an exact picture of what is known at all times. These techniques will allow researchers to determine if elements in the environment are perceived and processed by subjects, but do not allow a determination of how much information remains in memory, if the information is registered correctly in the mind, or what comprehension the subject has of those elements. Known physiological techniques, while providing useful, objective data, are not very promising for SA measurement.

Performance Measures

In general, performance measures provide the advantage of being objective and are usually non-intrusive. Computers for conducting system simulations can be programmed to record specified performance data automatically, making the required data relatively easy to collect. Several limitations exist in using performance data to infer SA,

  • Global measures. Global measures of performance suffer from problems of diagnosticity and sensitivity. Performance measures give only the end result of a long string of occurred in a given situation.
  • External task measures. One type of performance based measure which has been suggested involves artificially changing certain information or removing certain pieces of information from operator displays and then measuring the amount of time required for the operator to react to the even. Aside from the fact that such a manipulation is heavily intrusive and requires the subject to undertake new tasks involved with discovering what happened to the changed or missing data while attempting to maintain satisfactory performance on other tasks, this technique may provide highly misleading results.
  • Imbedded task measures. Some information about SA can be determined from examining performance on specific operator subtasks that are of interest. For instance, when evaluating an altitude display, deviations from proscribed altitude levels or time to reach a certain altitude can be measured. This type of detailed performance can provide some inferences regarding the amount of SA about a specific parameter that is provided by a certain display. Such measures will be more meaningful than global performance measures and will not suffer from the same problems of intrusiveness as external task measures.

Subjective Techniques

  • Self-rating. One very simple technique that has been used occasionally is to ask operators to subjectively rate their own SA. The main advantages of subjective estimation techniques are that they are inexpensive and easy to use.
  • Observer-rating. A second type of subjective rating involves using independent, knowledgeable observers to rate the quality of a subject’s SA.


In general, questionnaires allow for detailed information about subject SA to be collected which can then be evaluated against reality, thus providing an objective assessment of operator SA on a detailed level. This type of assessment is a more direct measure of SA and does not require subjects or observers to make judgments about situational knowledge on the basis of incomplete information.

Obtaining or Losing Situational Awareness

Obtaining SA

Operators use a variety of techniques and strategies to obtain situational awareness. They rely extensively on displays for their information, and also actively solicit and obtain information from additional sources. As Mumaw et al. (2000 9) write,
“We emphasize the contribution of the various informal strategies and competencies that operators have developed to carry out monitoring effectively. Although these strategies are not part of the formal training programs or the official operating procedures, they are extremely important because they facilitate the complex demands of monitoring and compensate for poor interface design decisions. Thus one could effectively argue that the system works well not despite but because of operators’ deviations from formal practices (p. 52)”.

Losing SA

Limited operator exposure to a situation, inadequate training, poorly displayed system information, and high workload, with other factors, can individually or in combination adversely affect situational awareness (Adams, Tenney, and Pew, 1995 1). Other factors, such as automaticity, can also affect operator ability to deal with high workload situations, and limit their ability to perceive novel or unexpected cues.

Jones (1997 7) found, as did Adams et al. that operators can lose or fail to obtain situational awareness when exposed to situations in which cues are seemingly similar to, but actually different from, those associated with their mental image of the situations. Jones and Endsley (1996 10) found that operators were more likely to notice and alter their situational awareness when exposed to cues that were considerably different from those associated with their mental images. The less cognitive effort operators expend in monitoring the system, the more likely they will fail to attend to critical situational cues.

During periods of high workload operators will almost certainly face competing demands on their attention, and can often be interrupted during their activities. When returning to their tasks their ability to maintain the situational awareness that they had acquired before the disruption will be reduced (Strauch, 2004, p.203 10).

In summary, high workload, competing task demands, and ambiguous cues can all contribute to an operator’s loss of situational awareness, even with experienced and well-trained operators.

Supporting evidence

The investigation carried out by NTSB (1996 [10])on air desaster involving American Airlines flight 965 enroute to Cali International Airport on December 20, 1995 revealed a situation of clear loss of situational awareness by both the captain and the first officer. When the controller cleared the flight into the airport the captain fed a wrong input into the Flight Management Computer (FMC) resulting the aircraft travelling into a wrong territory, away from the airport. When the crew realised that they lost position of the aircraft they carried out a series of poor actions and decisions. They were unable to attain correct information on the situation nor they were predicting a possible accident (the area around the Cali airport is well-known for high mountains). Their situational awareness was lost, until the Grownd Proximity Warning System (GPWS) alerted them about a collision. Unaware of the extended spoilers crew attempted to climb over the mountains. Aircraft crashed killing 160 of 164 people on board.

Refuting evidence

Way forward (to do list)

1. ADAMS M. J., Y. J. TENNEY & R. W. PEW (1995). Situation awareness and the cognitive measurement of complex systems. Human Factors, 1995, vol. 38, pp.85-104. ISSN: 0018-7208.
2. ENDSLEY R Mica (1987). The application of human factors to the development of expert systems for advanced cockpits. Proceedings of the Human Factors Society 31st Annual Meeting, pp. 1388-1392. Human Factor Society (Santa Monica, CA), 1987.
3. ENDSLEY R Mica (1988). Design and evaluation for situation awareness enhancement. Proceedings of the Human Factors Society 32st Annual Meeting, pp. 97-101. Human Factor Society (Santa Monica, CA, USA), 1988.
4. ENDSLEY R Mica (1995a). Measurement of situation awareness in dynamic systems. Human Factors, 1995, issue 1, vol. 37, pp.65-84. ISSN: 0018-7208.
5. ENDSLEY R Mica (1995b). Toward a theory of situation awareness. Human Factors, 1995, issue 1, vol. 37, pp.32-64. ISSN: 0018-7208.
6. ENDSLEY Mica. (2000). Theoretical Underpinnings of Situational Awareness: A Critical Review. New Jersey USA, 2000.
7. JONES D. G. (1997). Reducing situation awareness errors in air traffic control. In Proceedings of the Human Factors and Ergonomics Society 41st Annual Meeting. Human Factor Society (Santa Monica, CA, USA), 1997.
8. JONES D. G. & M. R. ENDSLEY (1996). Sources of situation awareness errors in aviation. Aviation, Space and Environmental Medicine, 67, pp. 507-512. ISSN: 0095-6562.
9. MUMAW R. J., E. M. K. J. VICENTE & C. M. BURNS (2000). There is more to monitoring a unclear power plant than meets he eye. Human Factors, 2000, vol. 42, pp.36-55. ISSN: 0018-7208.
10. National Transportation Safety Board (NTSB). (1996). Control flight into terrain: American Airlines flight 965. Washington, D.C.: New York.
10. STRAUCH Barry (2004). Investigating human error: incidents, accidents, and complex systems. Ashgate (Aldershot, UK), 2004. ISBN: 0754641228.
11. Wikipedia (2008). Situation awareness. Retrieved from on 26 September, 2008.

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