In the discussion on Human Factors and Unsafe Behaviors, we have already covered slip errors due to attentional lapse and memory lapses. Next, we will discuss an important category of unsafe behavior: mistakes resulting from errors in the mental model, which the HFACS refers to as decision making.
Mistake refers to actions taken with intent, but ultimately not achieving the desired goal, leading to undesirable results.
Many factors can lead to mistakes. Here, we will discuss two mistake models frequently discussed in the aviation field: Situational Awareness (SA) and Mental Model.
Situational Awareness (SA)
Situational awareness generally refers to understanding the environment. Due to its widespread use in the aviation industry, SA has become somewhat like a ghost: everyone has heard of it, but no one really knows what it looks like. People often cannot clearly articulate this cognitive process, ending up with critiques of it as an umbrella term (umbrella terms cover a wide range but have vague concepts). At such times, we should refer back to the foundational paper on situational awareness by Endsley (1995), which defines it as follows:
Situational awareness 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.
According to this definition, situational awareness is divided into three different levels:
Level 1 SA: Perception of the Elements in the Environment
There are many different types of information in the environment. Imagine a driving scenario: you see the width, length, and shape of the road; on the dashboard, you see the speed, RPM, gear, temperature, etc. For cockpit crew, external signals include terrain, wind, clouds and rain, or the positions of other nearby aircrafts. For the aircraft, in addition to basic altitude, speed, attitude, there are many different system status displays like electricity, fuel systems, etc. There might also be the departure, arrival procedures being executed, and the route, etc. These are various possible types of information in the environment.
Level 2 SA: Comprehension of the Current Situation
Next, integrating the way these elements are presented to understand the current situation. For instance, in a cockpit scenario, the EGPWS alert sounding, indicating excessive proximity to terrain, would be understood differently during the low-altitude landing approach phase versus the high-altitude cruise phase: the latter is more likely due to system anomalies leading to false alerts, indicating a need to address system issues rather than immediate altitude correction. Integrating situational cues to generate meaningful judgments is the most critical process in situational awareness.
Level 3 SA: Projection of Future Status
Based on the understanding from the second phase, predicting the future status in a short time frame. In the EGPWS case, if during the approach phase, with notable terrain nearby and poor visibility, failing to act immediately to maintain separation from the ground could pose immediate danger, necessitating immediate corrective action per the manual. However, in the cruise phase, if it is assessed as more likely a system anomaly, there may be less immediate danger—this projection is formed based on the mental model.
Goals, Decisions, Actions, and Feedback
Situational awareness occurs within tasks with clear goals and ideal states. After undergoing the aforementioned situational understanding processes, crew members use the understanding they have developed to make decisions, followed by actions once these decisions are confirmed.
Importantly, the components of the environment change following actions, altering the manifestation of various items of information. These results form feedback, serving as input for the next situational awareness process. If the execution results align with expectations, this can further confirm the results of situational awareness, increasing trust in the accuracy of current judgments. However, if results do not align with expectations, it may prompt questioning of the prior situational understanding, necessitating further effort for reevaluation. Essentially, situational awareness is a process of repeated confirmation.
Human Factors Affecting Situational Awareness
Even within the same goal and situation, different individuals may generate different situational understandings and thus take different actions. For instance, many have experienced the frustration of connecting a computer to a projector and ending up with no projection. While facing the same issue and information, often judgments regarding the problem and subsequent actions differ, resulting in varying levels of performance in resolving the issue. Some people quickly resolve such problems, while others cannot seem to identify the issue after a long time. Here, we categorize influencing factors into attention and knowledge and experience disparity.
Knowledge and Experience Disparity
Differences in individuals’ knowledge and experience represent the main divergence between novices and experts in problem judgment.
For example, suppose a patient reports having two different personalities within that talk to each other.
- Hearing voices that don’t exist might be a manifestation of hallucinations, raising suspicion of schizophrenia.
- Having two distinct personalities could lead to suspicion of dissociative identity disorder.
In order to confirm whether it is one of these two issues, a clinical psychologist might allocate equal time to inquire about symptoms related to these diagnoses. However, a more experienced psychologist might already recall some background knowledge upon hearing about the dual personalities’ symptoms:
- Schizophrenia is commonly seen in psychiatric outpatient settings. Anyone who has worked in an acute psychiatric ward should have encountered it; the prevalence in Taiwan is about 0.4% to 1%.
- Dissociative identity disorder is quite rare in Taiwan. Although there were more case reports from the 1920s to the 1970s, case numbers have dwindled since. Reliable prevalence statistics are unavailable.
Because of experience and knowledge, the experienced psychologist might choose to start questioning primarily about schizophrenia symptoms. Extensive experience and knowledge can enhance situational awareness, which is why we focus on interventions in human factors, primarily through training and case sharing. However, if an individual’s experience overshadows other perceptual cues, resulting in the overconfidence effect from social psychology, it can cause a breakdown in judgment during situational awareness.
Attention Processes: Perception, Cognition, to Automation
In previous chapters, we discussed attention, information processing, memory, and automation. These attention processes can also impact situational awareness. For example:
- If the attention workload becomes excessive, requiring focus on multiple items, the quality of situational awareness may decrease. For example, a fighter pilot might need to simultaneously monitor the relative position of enemy aircraft and handle their own aircraft’s abnormal conditions, thereby reducing situational awareness performance.
- If situational awareness demands place a heavy load on working memory, making it difficult to project future states as required in Level 3 SA. In the example of connecting a computer to a projector resulting in no display, if the projection system involves multiple layers of interfacing devices with numerous adjustable options, the limitation of considering multiple variables simultaneously due to working memory constraints makes future projection difficult.
Mental Model
Another concept related to situational awareness is the Mental Model. This mental model is roughly defined as follows:
A mental model is a mechanism whereby humans can generate descriptions of system purpose and form, explain system function and its observed states, and make predictions of its future states. – Rouse & Morris, 1985
Therefore, it can be said that:
The mental model can be viewed as a schema for a system. These systems can be seen as a set of (albeit slowly evolving) memory structures.
Consequently, the mental model is internalized knowledge of how things operate, traditionally described in psychology as a schema or representation. In aviation, for example:
- Airbus hydraulic systems have three different hydraulic systems: Green, Blue, and Yellow.
- In a holding pattern, different altitudes require different speeds. Below 14,000 ft, if no other regulation is specified on the CHART, it should comply with PANS-OPS at 230 kts. In the US, below 6,000 ft, speed should be reduced to 200 kts.
These are all operational knowledge needed during flight, termed mental models. As compared to situational models, situational models are understandings formed based on the context. They are synonymous here with the previously described situational awareness. They are founded on mental models, reflecting understanding formed based on the conditions of the situation at the time.
Practical Case: Japanese Car Rental Self-driving Incident
This relates to a personal case of my own. We’ll first introduce this story and then attempt to explain how problem assessment was conducted using the theories of mental model and situational awareness.
An Experience of Self-driving in Japan
Many friends might have had the experience of traveling in Japan by self-driving. Japan isn’t like Taiwan; aside from strictly obeying traffic rules, the primary focus needs to be on the left-hand drive. Vehicles drive on the left side of the road, with left turns being small turns and right turns being wide turns.
During a trip with friends driving through Japan, after arriving at our accommodation town in Hokkaido around 7pm, we were quite hungry, having not stopped much during the drive, worried about finding places open for dinner. Parking first and having dinner before heading to the hotel was an option, but resulted in superfluous parking fees. In an attempt to save expenses, we chose to push on a little longer, anticipating getting some takeaway to have at the hotel later.
While driving to find dinner, coming upon an overpass access, only a single lane with a road merging from the right rear. Continuing forward, feeling a road converging from the right rear with the lane divider line changing from solid to dashed.
Continued driving forward for about fifteen seconds and noticed a dividing island in the middle where the lane divider on my left became solid. The introduction of this island puzzled me. Typically in a single direction, there wouldn’t be a dividing island, or if there was, it should indicate that the two roads were diverging to different destinations. Without any sign indicating where either road led to, I was now concerned about turning the wrong way, going left or right into unknown roads, and never finding my dinner. I came to a stop before the dividing island.
Eventually, the car behind seemed to notice my anomaly, honking in reminder. Being a foreign person driving abroad, I interpreted the honk as urging, making me more agitated. The passenger beside me couldn’t quite grasp my confusion, realizing only that I wasn’t moving and urged me to continue forward. With this push, I decided to drive as per my most routinely practiced pattern: choosing the right-hand path.
The chosen road combined back with the left road after proceeding for about ten seconds. At that moment, I suddenly realized, I was in the counterflow; the traffic lights were on my left, the whole direction was incorrect. Immediately turning left onto the left side of the road, fortunately, this was a scarcely populated rural area in Hokkaido, causing no significant hindrance to others. Only the car behind me, having prompted with a honk, left wondering why I started driving against the traffic.
Case Analysis
Right-drive Mental Model Automation due to Fatigue
Mental Model (MM) is a stable memory schema. For those accustomed to right-drive in Taiwan for an extended period, the roads familiar with right-drive become the operational mental model. Although I knew what needed to be noted under left-drive conditions, darkening skies, hunger, and mild anxiety reduced cognitive resources, allowing the preexisting familiar automated process to take over unintentionally. At that moment, the right-drive mental model became the operating model in working memory.
The initial working mental model was something like this:
- Level 1: Noticed an additional road on the right and a road merging from the right rear.
- Level 2: Based on an automated right-drive mental model, the road joining from the right was in the same direction as mine.
- Level 3: Anticipated if going off-ramp, needed to stay in the right lane, and exit from the right front.
Understanding Conflicting Cues
The key situational awareness point here was noticing an island divider in the middle of the road. This anomaly arose because there was an inconsistency with my operating mental model: it shouldn’t generally exist in the middle of the same direction road absent directional indicators, leading to unfamiliar territory and potential conflicts in dinner avenue and course selection.
The mental model in operation was roughly as follows:
- Level 1: A divider was present with no indication where divided roads went.
- Level 2: The existence of a divider contradicts current “same-direction” mental model, unable to integrate into a comprehensible state.
- Level 3: (???) What is happening (Confused Emoji)
Stopping the car in the middle is a clear sign of Level 2 situational awareness failure, unexpected contradictions in situational cues needing time for understanding. A car behind sounding its horn signaled pressure, naturally guided by automatic process, I opted to turn rightward. This showcased a considerable dominance of automated processes.
Generating a Working Mental Model for Left-drive with Immediate Correction
Ultimately, at the intersection of merging roads, the mental model enacted was:
- Level 1: Encountered an intersection; my car was in the right lane, with traffic lights positioned leftward.
- Level 2: In a left-drive context, stopping at an intersection requires positioning on the road’s left side.
- Level 3: Currently counter-flowing, immediate correction needed.
Herein, we observe a mistake’s journey from occurrence to assessment and eventual correction.
Conclusion
- The phrase frequently mentioned in the aviation industry, situational awareness (SA), refers to the process of interacting with the environment within tasks: (1) perceiving various types of environmental information, (2) executing an integrated comprehension of the situation based on the information, and (3) anticipating future states based on comprehension. Situational awareness originates from having concrete goals and making decisions based on awareness results, followed by action implementation resulting in outcomes, using these outcomes to validate the correctness of situational awareness.
- Different individuals may have different situational awareness in the same situation due to varying human factors like attention, perception, working memory, short-term and long-term memory, etc.
- Distinguished from situational awareness, a mental model (MM) refers to a set of stable memory structures. Therefore, mental models represent operational knowledge. The aviation industry’s concept of a shared mental model denotes a group possessing identical operational knowledge, hence when two individuals have common thought content.
