Modern ships are equipped with highly sophisticated navigation systems. ECDIS, radar overlays, AIS integration and automated sensor inputs have transformed the bridge into a powerful information centre. Yet despite these advances, navigation incidents continue to occur, and investigations often reveal a common underlying factor: human cognitive bias.

One of the most pervasive and dangerous of these is confirmation bias.

During my work as a Navigation Assessor, conducting onboard assessments and bridge team evaluations across a range of vessels, I have repeatedly observed how confirmation bias can subtly influence decision-making on the bridge. It is rarely deliberate and seldom recognised by those experiencing it. Yet its consequences can be significant.

When the Mind Decides Before the Evidence

Confirmation bias occurs when an individual forms an early assumption about a situation and then unconsciously interprets subsequent information in a way that confirms that assumption. In navigation, this often manifests when an officer believes the vessel’s position, course, or traffic situation is correct and then begins interpreting all available information through that belief.

During navigation assessments I often ask officers a simple question:

"How do you know the vessel is exactly where you think it is?"

The answers usually include references to GPS position, ECDIS track monitoring or radar overlay. These are, of course, valuable tools. However, the real question is not what information supports the assumption, but what information might contradict it. This distinction is critical.

Modern Bridges and the Illusion of Certainty

Integrated bridge systems present navigators with a highly coherent picture of the vessel’s situation. When radar overlays align with the ECDIS display and AIS targets appear correctly positioned, the bridge team can quickly develop a strong sense that everything is functioning as expected.

However, during assessments I occasionally introduce small verification exercises, such as requesting:

• A radar range and bearing position fix

• A visual bearing comparison

• An echo sounder check against charted depth

  
  

In some cases, these checks reveal discrepancies that had gone unnoticed because the bridge team had already accepted the electronic position as unquestionably correct. The systems themselves are not the problem. The danger arises when the navigator’s mind stops questioning them.

The Subtle Influence of Expectation

Confirmation bias often emerges most clearly during coastal navigation and pilotage waters, where navigators expect the vessel to follow the planned track precisely. Once the officer believes the vessel is correctly positioned on the track, contradictory cues may be unconsciously dismissed:

• A radar range slightly shorter than expected

• A visual bearing that does not quite align

• An unexpected echo sounder reading

Rather than prompting immediate investigation, these cues may be rationalised as minor instrument inaccuracies or environmental factors. This is not negligence. It is simply how the human brain naturally processes information when operating under routine conditions.

The Challenge of Experience

Interestingly, confirmation bias does not only affect inexperienced officers. In fact, experience can sometimes strengthen it. Experienced navigators develop strong mental models of how situations typically unfold. While this expertise is invaluable, it can also lead to situations where officers see what they expect to see rather than what is actually present. During bridge team observations, I occasionally see junior officers hesitate when something appears inconsistent but remain silent because a senior officer appears confident. In such situations, the bridge team can unintentionally reinforce the same incorrect assumption.

Creating a Bridge Culture That Questions Assumptions

The most effective navigators I encounter during assessments share a common trait: they actively challenge their own assumptions.

Rather than asking:

"Does the information confirm my position?"

They ask:

"What information might prove that I am wrong?"

This mindset encourages navigators to continuously cross-check information using independent sources such as radar ranges, visual bearings, parallel indexing and echo sounder verification. Equally important is a bridge environment where questioning is encouraged. A junior officer who feels comfortable saying:

"Captain, the radar range does not match our charted position"

Modern navigational training rightly focuses on the operation of increasingly sophisticated equipment. However, equal attention must be given to the human factors that influence how navigators interpret the information those systems provide.

Confirmation bias is not a failure of competence. It is a natural cognitive tendency that affects all decision-makers. Recognising it is therefore an essential component of modern Bridge Resource Management and navigational safety.

During navigation assessments I often remind bridge teams of a simple principle:

The most dangerous moment in navigation is when we become certain that everything is correct.

Maintaining a healthy degree of professional skepticism is one of the most powerful safeguards available to the modern navigator.

A Simple Discipline for Safer Navigation

One habit I encourage during onboard assessments is for officers to periodically ask themselves a single question:

“What evidence would prove that my assumption is wrong?”

If bridge teams consistently apply this discipline, confirmation bias loses much of its power. Ultimately, safe navigation does not depend solely on technology or procedures. It depends on the mindset of the navigator. And the most effective navigators are those who remain prepared to question what appears to be obvious.

Captain Keith Stevens is an experienced Navigation Assessor conducting onboard bridge team assessments and navigational audits focused on improving the safety of navigation and developing navigators’ decision-making and situational awareness.