Pilots of commercial airliners are letting their minds wander a lot more frequently than they used to, but don't cancel that flight to Hawaii just yet. According to a recent study, this distraction occurs only about a fifth of the time and only among pilots using automated cockpits.

"Glass cockpits" -- highly automated cockpits that relieve pilots of tedious control tasks -- were designed to free up the minds of pilots so that they can think ahead. However experts have wondered how effective these cockpits really are, raising concerns that too much free time may lead to pilots getting distracted from a job that has put an average of 300 human lives in their hands each flight.

A study published in the scientific journal Human Factors details how researchers determined what pilots are frequently thinking when working in a highly automated cockpit, compared to a more manual one.

According to the study, researchers from the University of California and the National Aeronautics and Space Administration in Moffett Field, California, had a total of 18 licensed airline pilots "fly" a Boeing 747-400 simulator. These simulators had two levels of cockpit automation, and pilots were randomly assigned to use one or the other.

While in the simulator, each pilot was asked a series of questions pertaining to what they were currently thinking about. The researchers asked that the pilots categorize the nature of their thoughts as one of three things -- a specific task at hand, a higher-level flight related thought, or thoughts completely unrelated to the flight.

Predictably, the researchers found that the pilots less frequently reported task-at-hand thoughts when using the higher level of automation. According to the authors of the study, this in-turn appears to be giving pilots of automated aircraft more time for higher-level flight-related thought such as planning ahead. According to the results, high-automation pilots reported higher-level flight thoughts 56 percent of the time, while the pilots of less automated cockpits reported only doing this 29 percent of the time.

However, pilots of highly automated cockpits also reported thinking thoughts unrelated to flying more than one fifth of the time, compared to the other group of pilots who only spent seven percent of their time distracted by flight-unrelated thoughts.

With these results, the researchers were able to conclude that while automated cockpits did indeed allow pilots to think ahead more frequently, they also allowed for more distracting thoughts.

As this small-sample study was highly dependent on the honesty of the subjects, the authors of the study were able to conclusively say if these fort of distractions are the average among all pilots, nor could they say if they pose a danger to passengers.

Still, the authors of the study note that a past 2012 study published in Psychological Science, argues that frequent task-unrelated thought actually keeps you mind sharper, exercising your working role memory when it would not normally be in use.

The study "Thoughts in Flight," was published in the May issue of Human Factors, a journal of the Human Factors and Ergonomics Society.