Cognitive Biases in Runway Alignment: A Comprehensive Analysis

Introduction

Runway alignment is a vital aspect of aviation safety, ensuring that aircraft are positioned correctly for takeoff and landing. Errors in runway alignment can lead to serious consequences, such as collisions, runway excursions, or loss of control. This comprehensive guide explores the common cognitive biases that contribute to these mistakes and provides practical strategies for preventing them.

Understanding Runway Alignment Errors

Runway alignment errors occur when pilots misalign their aircraft with the runway centerline, leading to potential safety hazards. These errors can be caused by a variety of factors, including pilot error, fatigue, workload, and cognitive biases.

The brain can mistakenly align with the runway edge instead of the centerline due to several cognitive factors, primarily driven by perception errors, workload, and cognitive biases. Here are the main reasons why this misalignment happens:

1. Visual Illusions and Perception Errors Runway Alignment

• Lighting and Contrast: Runway edge lights can appear more prominent, especially during night operations or low-visibility conditions, making them easier for the brain to latch onto compared to the centerline, which may have less visible markings.
• Depth Perception: At certain angles, particularly during night or low-visibility approaches, the brain may misjudge distance or width, leading pilots to think they are aligned with the centerline when they are actually aligning with the edge.
• Geometric Illusion: When pilots are in certain positions on the runway or have a skewed visual perspective, their brain might interpret the visual field as aligned with the runway edge due to the spatial arrangement of lights or markings.

2. Cognitive Biases Runway Alignment

• Confirmation Bias: Pilots may have an expectation about the runway layout based on previous experiences. When visual cues seem to confirm their assumptions, the brain aligns with those cues (e.g., assuming edge lights are the centerline) without rechecking their accuracy.
• Anchoring Bias: Once a pilot fixates on a specific visual reference, such as the first set of lights they see (runway edge lights), they might continue to rely on that reference, ignoring subsequent information that could correct their perception.
• Availability Heuristic: If a pilot recently experienced or heard about alignment issues, they may become overly focused on avoiding other errors and miss critical cues about their own alignment.

3. Inattentional Blindness Runway Alignment

• Task Saturation: During critical moments like takeoff or landing, pilots are often managing multiple tasks at once—communicating with air traffic control, monitoring instruments, and managing controls. This can lead to inattentional blindness, where the brain misses important visual details (e.g., centerline lights) because attention is focused elsewhere.
• Cognitive Load: High mental workload increases the chance of overlooking important cues. Pilots may miss the centerline because their brain is processing too much information, and their attention shifts to more obvious cues, like the edge lights.

4. Fatigue and Stress

• Fatigue and stress can impair cognitive function, reducing a pilot’s ability to detect errors in alignment. The brain defaults to taking mental shortcuts, relying on obvious visual cues like edge lights instead of focusing on a more precise and less prominent centerline.

5. Poor Visibility and Environmental Factors

• In conditions of low visibility, such as fog, rain, or night operations, the runway centerline may be difficult to see. Edge lights, which are designed to be bright and easily visible, can dominate the visual field. The brain may instinctively guide the aircraft toward the clearer visual reference (the edge lights) rather than the harder-to-detect centerline.

6. Instrument and Automation Over-reliance during runway alignment

• When pilots rely too heavily on automated systems or instruments, they may neglect to double-check visual cues, leading to alignment errors. If the automation provides incorrect or incomplete data, pilots might inadvertently align with the runway edge because they aren’t fully engaged with the visual cues that indicate proper alignment.

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Accidents and Incidents

Unauthorised takeoffs from taxiways –
an in-depth analysis of past occurrences
Paper presented at the International Society of Air Safety Investigators 2023 Annual Seminar,
Nashville, Tennessee, August 22 – 25, 2023.

Conclusion

The brain aligns with the runway edge instead of the centerline due to a combination of visual misinterpretations, cognitive biases, high workload, and environmental factors. The dominance of bright edge lights in poor visibility, fatigue, and task saturation can all contribute to these alignment errors.

Taxiway Layout Involvement

• 72% (18 occurrences): Dual parallel taxiways.
• 20% (5 occurrences): Single parallel taxiways.
• 8% (2 occurrences): Non-parallel taxiways.

Outcomes of Taxiway Takeoff Errors

• 68% (17 occurrences): Pilots successfully stopped on the taxiway.
• 28% (7 occurrences): Pilots continued their takeoff without further consequences.
• 4% (1 occurrence): Pilot aborted takeoff but could not stop, ending on the safety strip without damage.

Abort Speed Ranges

• Abort speeds ranged from 15 to 133 knots (GS) and were randomly distributed based on:
  • Time of error detection.
  • Delay in initiating the abort.

Collision Risk

• In 1 case, another aircraft was on the same taxiway, but no collision occurred due to timely recognition by the crew.

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Insights and Implications

1. Layout Risks:
   • Dual parallel taxiways are a dominant factor in these incidents, likely due to their similarity in orientation to runways, which increases the chance of misjudgment.
2. Effective Abort Handling:
   • Most errors (68%) are mitigated through safe stops, emphasizing the importance of pilot training and situational awareness.
3. Proactive Solutions:
   • Enhancing visual and procedural cues, such as clearer markings, advanced lighting, and stricter adherence to stop bar protocols, can mitigate risks further.
4. Infrastructure Focus:
   • Airports with dual parallel taxiways should prioritize additional safeguards, as they represent a disproportionate share of occurrences.

This summary highlights the critical need for a comprehensive approach to address both human and structural factors contributing to unauthorized taxiway takeoffs.