What’s common between a phone conversation & what could have been the worlds worst air disaster:mindFly

Most of the laws banning cell phone use while driving has focused inappropriately and exclusively on hand-held phones. Whether or not cell phone use while driving should be regulated is a political question, but the cause of the distraction is an empirical one. Public officials do a disservice when they fail to convey the real reasons why using a cell phone while driving is dangerous.

According to Christopher Chabris and Daniel Simons authors of the book “the invisible gorilla”, “the enforcement campaign spreads misinformation by implying that it’s the “hand-held” aspect of cell phone use that causes the problem. In reality, the real distraction has nothing to do with having both hands on the wheel — it’s the conversation itself (coupled with the challenge of communicating with someone not in the car). Using a hands-free phone doesn’t eliminate the distraction, and it might even be given people a false sense of confidence if they think that switching to a hands-free phone makes them safer”. The brain does not register the unexpected events.

Everyone is proficient in driving a car and driving with one hand on the steering wheel is not an exception.  There are times when one completes a journey and at the end of it is unable to recall the route taken to reach the destination whereas all turns and stops were executed safely.  In this scenario, the driver was lucky that another vehicle or a pedestrian did not appear unexpectedly since the brain will not register these unexpected events.   This phenomenon is called Inattentional Blindness.

The pilot of the Air Canada 759 approaching to land at San Fransisco on 02 July 2017 aligned the aircraft to land on a taxiway, which had four big jets carrying almost a 1000 passengers.  The pilot mistook the taxiway for the landing runway and continued to descend over the taxying aircraft to reach the lowest height of 60 feet before realizing the mistake and taking evasive action.  How could the pilot not see such large jet aircraft in front of him is intriguing?

Flight profile of Air Canada 759 (Credit: Open source NTSB report)

Inattentional blindness

Everyone has some awareness of the limited capacity of attention, and our social behavior makes allowances for these limitations. Intense focusing on a task can make people effectively blind, even to stimuli that normally attract attention (Kahneman, 2011). When engaged in a demanding task, attention can act like a set of blinders, making it possible for salient unexpected stimuli to pass unnoticed right in front of our eyes (Neisser & Becklen,1975). This phenomenon of “sustained inattentional blindness” is best known from Simons and Chabris’ (1999) study in which observers attend to a ball-passing game while a human in a gorilla suit wanders through the game. Despite having walked through the center of the scene, the gorilla is not reported by a substantial portion of the observers.

The experiment

Does inattentional blindness (IB) still occur when the observers are experts, highly trained on the primary task? (Drew, Võ, & Wolfe, 2013) In computed tomography (CT) lung cancer screening, radiologists search a reconstructed ‘stack’ of axial slices of the lung for lung nodules that appear as small light circles. A series of the experiment conducted with 24 radiologists (mean age: 48; range 28–70), they had up to three minutes to freely scroll through each of 5 lung CTs, searching for nodules as their eyes were tracked. Each case contained an average of 10 nodules and the observers were instructed to click nodule locations with the mouse. On the final trial, a gorilla with a white outline was inserted into the lung.

In the experiment, 20 of 24 expert radiologists failed to note a gorilla, the size of a matchbook, embedded in a stack of CT images of the lungs. This is a clear illustration that radiologists, though they are expert searchers, are not immune to the effects of IB, even when searching medical images within their domain of expertise. Potchen (2006) showed that radiologist could miss the absence of an entire bone. Why do radiologists sometimes fail to detect such large anomalies? Of course, as is critical in all IB demonstrations, the radiologists were not looking for this unexpected stimulus. Though detection of aberrant structures in the lung would be a standard component of the radiologist’s task, our observers were not looking for gorillas. Presumably, they would have done much better had they been told to be prepared for such a target. Moreover, the observers were searching for small, light nodules.

The reason crew did not sight the three large passenger jets can be attributed to inattentional blindness. A fatigued crew had aligned the aircraft with a taxiway due to expectation and confirmation bias. With limited cognitive capacity and analytical skills due to fatigue and biases, the crew further got a confirmation from the ATC that the runway was clear. During the approach to land, the pilot’s attention was focused to keep the aircraft on the lateral and vertical profile i.e., maintain the centerline and aim for the touchdown point. They do not normally expect or look out for aircraft on the runway since they assume that the ATC is controlling the access to the runway. Inattentional bias sets in when maximum attention is focused on a particular activity, here the crew were focused on the dimly lit taxiway and trying to fly a vertical profile with limited guidance that they were blinded to unexpected objects in their field of vision. It relates to the gorilla in the CT scan experiment, which could not be detected since the radiologists did not expect them to be there and were focused on looking for smaller sized images.

Conclusion

These are human cognitive limitations, which have been highlighted in other means of transport accidents. The crew needs to be aware of their limitations, especially when a task demands too much attention and/or when they are fatigued. Awareness of one’s limitation, trusting the instruments and having an adequate cross check with the crew and ATC can help to prevent the bias.

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