Confirmation Bias: Subtle but lethal

Photo credit: AP

NTSB investigators yesterday offered up a perfectly plausible explanation for why two very seasoned airline pilots on a perfectly dawning summer morning pulled their perfectly fit CRJ100 regional jet onto a tragically unfit runway (too short) and ploughed into trees and other obstacles before coming to rest a half mile from the airport, killing 49 of the 50 aboard…

Confirmation Bias.What is confirmation bias? defines it as “a tendency to search for or interpret new information in a way that confirms one’s preconceptions and avoid information and interpretations which contradict prior beliefs.”

In the tragic case of Comair Flight 5191, which crashed nearly a year ago at the Lexington Kentucky Blue Grass Airport, CB meant the pilots somehow had become convinced, as they stopped at the hold-short line for Runway 26, that they were actually stopped at the hold-short line for Runway 22, the runway to which the air traffic controller had instructed them to taxi, and the runway they had verbally accepted as the runway to which they were to taxi to and takeoff from.

The crew’s actions remain a mystery still, even after an 11-month investigation with 31 investigators and support staff that spent 13,000 man-hours coming up with probable causes, contributing factors and recommended fixes to the aviation system.

NTSB investigators, speaking at the final public hearing to discuss the investigative report, said the pilots were physically fit, were not rushed and had multiple external cues that should have alerted them to the error.

When CB creeps in though, people put “less emphasis on contradictory information,” NTSB staff said. For instance, the absence of any runway lights (the runway they chose was an unlit, narrow general aviation runway not approved for night operations), could have seemed logical given that the first officer had earlier commented on the cockpit voice recorder that there were various lights not working on his flight into the airport.

Board members were clearly troubled by how to come to grips with CB, and how to spare others from the same fate. “As the investigation unfolded, we found that there were no easy explanations, no simple solutions,” said NTSB board member Debbie Hersman, who was part of the go-team that traveled to Lexington shortly after the accident and spent about a week on-scene for the investigation. “The ‘Ah-Hah!’ moment remains elusive to us,” she lamented “Instead, this investigation led us into the briar patch of human behavior.”

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