But the Northwest pilots were on their laptops, Mr. Babbitt said, doing work unrelated to the flight, a prohibited activity. “It doesn’t have anything to do with automation,” he said. “Any opportunity for distraction doesn’t have any business in the cockpit. Your focus should be on flying the airplane.”

Automation is generally considered a positive development in aviation safety because it reduces pilot workload and eliminates errors in calculation and navigation. “The introduction of automation did good things,” said Key Dismukes, chief scientist for aerospace human factors at NASA. But it changed the essential nature of the pilot’s role in the cockpit. “Now the pilot is a manager, which is good, and a monitor, which is not so good.”

Hugh Schoelzel, the vice president of safety at Trans World Airlines — a carrier acquired by American Airlines in 2001 — said most pilots had at one time or another lost track of where they were in flight. “Anyone who says they haven’t is either being disingenuous, or hasn’t been paying attention,” he said.

The episode in which the returning captain had to act quickly to save the airliner from a near stall was discovered by the Commercial Aviation Safety Team, an airline industry group, as it reviewed thousands of reports filed by pilots to NASA’s Aviation Safety Reporting System to see if automation caused pilots to mishandle problems or to become confused or distracted. The group’s study, which ran from 2005 to 2008, highlighted 50 events in the five years prior to 2005. In 16 of them, the pilots’ failure to monitor the automation or the location of the aircraft was cited.

Image Frank Chapman, a test pilot, before the control panel in the cockpit of an Airbus A380 superjumbo jet in Frankfurt. Credit... Thomas Lohnes/Agence France-Presse — Getty Images

“I’m inclined to say it’s the very reliability of something that takes us out of the loop,” said Mr. Dismukes, who has written about the effects of automation on safety. “You may know, ‘Never turn your back, always check,’ and people may have that intention. But it’s hard to maintain that in practice when you’re not physically controlling the aircraft.”

Finding the balance between too much technology and too little is crucial, according to William B. Rouse, an engineering and computing professor at the Georgia Institute of Technology. “Complacency is an issue, but designing the interaction between human and technical so the human has the right level of judgment when you need them is a design task in itself,” Mr. Rouse said. “When the person has no role in the task, there’s a much greater risk of complacency.”