Breaking The Accident Chain

The danger of multitasking and inattentional blindness: hang up, focus and pay attention

Mistakes are a part of life, but when it comes to aviation, sometimes even a simple mistake can lead to disaster. This one happened in early January 2007, on a cool, clear Los Angeles morning. The second pilot of N77215, a Citation jet getting ready to depart out of Van Nuys Airport, arrived at the plane while it was being fueled to load some baggage. The pilot and line person spoke while the pilot loaded bags into the front left baggage compartment. When he finished fueling, the line person informed the pilot that they'd have to tow the aircraft to a different area for startup. The pilot was seen closing the front baggage door, but he didn't latch it shut. After the plane was moved, the first pilot arrived, and the line person left to marshal another aircraft from the ramp. When he arrived back at the Citation, he noticed that the crew took an extraordinary amount of time getting ready in the cockpit. The aircraft eventually taxied out and was cleared for departure. Just as the plane rotated during the takeoff roll, the forward baggage door suddenly popped open. Witnesses reported that the plane slowed and turned downwind in an apparent effort to return to the airport. Unfortunately, it never made it. Perhaps distracted by the flailing door, or concerned that it might rip off, the pilot slowed the aircraft enough to completely lose control of the aircraft. It stalled and spun into a residential neighborhood, killing the crew.

This event didn't happen to an inexperienced crew. The 72-year-old pilot, who was a former airline captain, reported his total flight experience at over 38,000 hours, and the second pilot had 1,693 hours of flight time. The Citation 525 is equipped with a warning system that shows when the forward baggage door isn't properly secured, and previous incidents where doors have come open have demonstrated that the Citation can be successfully flown with the door open. This was a tragic end to a series of events that started with a seemingly simple mistake.

It doesn't matter what you fly. Pilots at all levels land gear-up, take off with baggage doors open, taxi away after startup with a ground power cart still connected, start engines with covers in place, depart with a tow bar attached, take off from taxiways, forget to replace a fuel cap and a host of other mistakes too numerous to list. Most of these events start with a simple mistake, and there are often multiple warnings that something is wrong, yet even experienced pilots miss all the clues. Sometimes, the results are inconsequential, but most of the time, the results are very expensive and sometimes fatal. These kinds of mistakes caused by acts of omission---simply forgetting or missing something---are particularly insidious. Under the right set of circumstances, the human brain operates in a way so that these kinds of mistakes are very easy to make and sometimes nearly impossible to catch. Let's take a look at how we process information and what conditions are the most likely to set us up for potentially catastrophic acts of omission.

Recent studies show the human brain is simply not good at processing multiple tasks at one time.

The Danger Of Multitasking
As pilots, most of us pride ourselves on our ability to handle multiple tasks at once. We're trained to aviate, navigate and communicate all at the same time during normal operations. Our daily routine of reading email and listening to the news on the radio while answering the phone reinforces a belief that we can effectively handle multiple tasks at one time. Recent studies show otherwise---the human brain is simply not good at processing multiple tasks at one time. It turns out that our modern lifestyle of trying to do multiple things at once is actually having an adverse effect on our ability to completely focus on even one task at a time.

To understand why, we need to look at how multitasking works. A true multitasking processor has multiple processing units, each fully dedicated to a given task. The processors run independently, without regard to the others, to complete each task uninterrupted. Studies show that with regard to cognitive events, the human mind simply doesn't work this way. Instead, the brain must multiplex---switching rapidly between multiple tasks to do more than one thing at a time. This is a common strategy in the computer world where a single high-speed processor is used to perform multiple tasks at once. The processor flips between tasks at high speed, flawlessly keeping track of where it is in each task to make sure nothing gets dropped.

It doesn't matter what you fly. Pilots at all levels land gear-up, take off with baggage doors open, start engines with covers in place!

This is where it's easy to run into trouble. If you try to work on too many tasks at once, it becomes very easy to forget where you are. We can generally switch tasks at a rate of one to 10 times per second, depending on the task. Cognitive tasks that require thinking and logic tend to require more time between switches than autonomic physical tasks, such as driving or listening to music. Studies have shown that once you get more than two things going at once, the likelihood for making mistakes goes way up. Furthermore, in a world where we're constantly switching between tasks, we're essentially practicing the art of NOT paying attention and losing our ability to prioritize. Our attention span necessarily has to be reduced as we switch between multiple tasks. When faced with a single task, it becomes even easier to get sidetracked by external distractions---it's what we do best. Although productivity suffers, this modus operandi might work at a desk where we have plenty of opportunity to pick up a dropped ball, but it can quickly lead to disaster in the cockpit with a lot going on.

Inattentional Blindness
An even more surprising fact is that by concentrating too hard on one thing in a multitasking situation, the human mind can quickly become unable to process information not related to the task at hand. When this happens, you become completely blind to things in plain sight that you'd otherwise notice immediately. The effect, called inattentional blindness, was first identified by Arien Mack and Irvin Rock in 1992 and made famous by a study done by Daniel Simons of the University of Illinois at Urbana-Champaign, and Christopher Chabris of Harvard University. In their study, a group of subjects were shown a short film showing three people in black T-shirts and three people in white T-shirts moving around and tossing two basketballs back and forth. The subjects were asked to count how many times the players in white shirts caught a ball. There's a lot of movement as the balls fly back and forth, and in the middle of the film, a woman in a black gorilla suit walks onto the floor, stops, turns toward the camera and waves. She slowly turns and exits screen left. When the subjects were asked if they had seen anything unusual, 50% of the subjects didn't report seeing the gorilla. Many subjects couldn't see the gorilla even when they tried the exercise a second time.

In another experiment by Steven Most, Daniel Simons, Christopher Chabris and Brian Scholl, participants watched objects moving randomly on a computer screen. They were instructed to attend to the black objects and ignore the white, or vice versa. After several trials, a red cross appears and moves across the display for about five seconds. About a third of participants didn't report seeing the cross. The results of the experiment demonstrate that even though the cross was different from the black and white objects, both in color and shape, a significant number of subjects still couldn't see it.

In the late 1990s, NASA conducted a similar experiment to see if commercial pilots would notice distractions while making landings in a flight simulator. Interestingly, about 25% of the trained pilots noticed nothing out of the ordinary and landed on top of the distraction. Untrained pilots who had no preconception of what to expect during a landing always spotted the distraction.

Clearly, inattentional blindness has sobering implications for those of us who operate aircraft. It explains why a distracted pilot who lands with the gear up swears that the gear warning horn never sounded when it's shown to be working perfectly afterward. It can explain why items in plain sight, such as unlatched baggage doors or a missing fuel cap, become invisible during a hectic preflight. It may even explain why some pilots may miss critical communications on the radio during periods of high workload. An experienced, high-time pilot who turned onto a taxiway when cleared for takeoff was warned multiple times that he was on a taxiway, yet he continued his takeoff run, narrowly passing over a regional jet on the taxiway. Our minds are simply incapable of perceiving extraneous information when we become fixated or overloaded. Test subjects who didn't see the gorilla in the study film were stunned when they were told about the gorilla and viewed the film a second time---just like pilots who overlook a critical item that results in an accident. It's a valuable lesson that under the right circumstances, inattentional blindness can happen to anyone, including experienced, detailoriented, careful pilots.

In A Hurry
Aviation attracts type-A, detail-oriented personalities. Many of us in that category have a high internal sense of urgency that can lead to self-induced time pressure. Often, the rush has nothing to do with reality. Time pressure creates a tendency to try to take on too many tasks at one time in order to get them completed before the clock runs out. It's important to understand that the rush to get all this stuff done creates conditions for forgetting things and for overfocusing, which increases the odds of experiencing inattentional blindness.

What's The Cure?
So, how can these traps be avoided? Probably the very first thing to do is admit that this could happen to you. Believing that this is somebody else's problem or that it affects only inexperienced or careless pilots may be the first step down the path to an accident. Admitting the possibility of missing something critical should help keep your guard up during periods of high workload.

Second, slow down, figure it out and then do what you need to do. There are only a very small number of emergencies or situations that actually require immediate, rapid action. There's some truth in the old saying about the best way to handle an emergency in the cockpit: start by winding your watch. Slow down, pull the checklist and do one thing at a time in a methodical way.

Third, learn to recognize when you're juggling two or more tasks at a time. Consciously slow down, prioritize your actions and then take one thing at a time. Arrive early at the airport and get things ready well before your scheduled departure time or before passengers arrive, and you'll start off with a relaxed attitude. If the workload starts to get out of hand, off-load some of the tasks onto an autopilot, copilot or competent passenger.

Finally, double-check what you've done. It will help you slow down and make sure that you haven't missed something.

These steps are necessary for good crew resource management (CRM) and especially for single-pilot resource management (SRM) if you fly alone. Remember: admit, slow down, do one thing at a time, double-check the next time you approach your airplane and have a safe flight!


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