Amanda Ripley Author of The Unthinkable

Yesterday, federal investigators interviewed the pilots of the Northwest plane that overshot its Minneapolis-St. Paul destination by 110 miles last week. So far, some people have been skeptical of the pilots’ vague explanation to date: that they got distracted during a heated discussion about airline policy and lost track of time.

But I don’t find that explanation hard to buy, personally. This problem is well-known to pilots. So well-known that they have a name for it--“task saturation”--as well as specialized training to try to avoid it.

The brain works on one thing at a time. This much we know. And pilots have gotten into terrible trouble before because they were absorbed in one thing to the exclusion of all others.

Cockpit myopia was a huge issue in the 1970s, when airplane pilots started to realize that the more stressed they got, the less they saw. As stress increased, they tended to become mentally obsessed with one data point to the exclusion of all others.

Consider the story of the green light. On the evening of December 29, 1972, an Eastern Air Lines jet coming from New York City began its final approach to Miami International Airport. The flight had been uneventful, and the weather in Miami was clear. The plane carried 163 passengers, most of them holiday travelers.

But when the pilots tried to lower the landing gear, they didn’t get a green light indicating that the gear was fully down.At 11:34 P.M, the captain, who had more than three decades of experience, called the Miami control tower to explain that he would have to circle while they worked on getting the green light. The plane climbed to two thousand feet and began a wide U-turn over the airport. For the next eight minutes, the flight crew tried to figure out what was wrong. Why wouldn’t the light go on? The captain ordered two different people to try to visually confirm that the gear was down, but they couldn’t see anything in the dark.

At 11:40, a half-second alarm tone went off in the cockpit, indicating that the plane had deviated from its altitude. The transcript from the cockpit voice recorder shows that no one said anything about the alarm. It was as if they hadn’t heard it at all. The crew continued to speculate about possible reasons for the light problem. But then, two minutes later, the first officer noticed another problem.

“We did something to the altitude,” he said. “What?” the captain said.

The first officer backtracked: “We’re still at 2,000, right?”

Then the captain said, “Hey, what’s happening here?”

Another warning sound began to beep, more insistently this time. Two seconds later, the plane crashed into the Everglades, 19 miles from the airport.

Investigators would find that the plane had been in fine working order—except for the lightbulbs in the landing-gear indicator, which had burned out. While the flight crew worried about the light, the plane had dipped toward the earth. When it sliced into the soggy marshland,it disintegrated on impact. The wreckage was scattered over an area 1,600 feet long and 330 feet wide. A total of 101 people died.

The crash, and several other unnervingly similar accidents, convinced aviation researchers that pilots needed to be trained to avoid task saturation.“This happens to everybody under stress,” Rogers V. Shaw II, who trains pilots for the FAA, told me when I was working on my book. “If there’s not enough training, you get channelized on one thing, and you forget the whole big picture.”

Today, Shaw trains pilots to proactively scan their instrument panels, over and over again, to counteract the tendency to fixate on one problem. He also teaches pilots to make sure one member of the flight crew remains focused on flying the plane at all times.

It’s too soon to say if task saturation was the cause of the Northwest incident. But the prospect that it might be reminds me of the power of the green-light story--a lesson not just for pilots but for anyone who drives anything. Your brain wants to work on one thing at a time. And no, you are not different, and no, that email you feel you absolutely must read while on the highway is not actually very important.