(CBS News) A new survey of British airline pilots finds more than half fell asleep while flying, and almost one in three said when they woke up, the other pilot had nodded off. About half surveyed by the polling company ComRes on behalf of the British Airline Pilots' Association (BALPA) said pilot fatigue was the biggest threat to flight safety -- three times more serious than any other threat
And it isn't just a British problem, according to CBS News aviation and safety expert Chesley "Sully" Sullenberger: "Pilot fatigue is a worldwide problem," he said. "It's very serious and it's underreported largely because of fear and also the perception among pilots that reporting does no good, that the reports that have been submitted have not been effectively acted upon."
Falling asleep while flying may not be illegal or wrong, CBS News travel editor Peter Greenberg said on "CBS This Morning" -- the real questions he said are about workload in the cockpit and the pilots getting enough sleep. He said, "Pilots don't necessarily fly the planes as much as they monitor systems these days, but the second issue which is much more important is are they getting enough rest."
The pilots recently surveyed, Greenberg also noted, are self-reporting these incidents because they are angry about the European Union's efforts to relax the actual workload requirements of the pilots to make them to work longer hours. Greenberg said, "That's why they're going public with this."
In an effort to curb this kind of dangerous flying, Greenberg said changes in the rules are in the works to promote better sleep for pilots. A new Federal Aviation Administration rule -- to go into effect in January 2014 -- include a minimum 10-hour rest period and eight hours of uninterrupted sleep.
Greenberg said, "The key here is not that they're (sleeping) on the plane, it's a question of how much rest they're getting either before their flights or between their flights and the current rules have recently just been amended, but the current rules are that you have to have at least eight hours between flying.
He continued, "Because the way the rule now works, it's based on when the plane gets to the gate, the clock starts ticking on eight hours -- that's ridiculous -- because it may take the pilot another hour and half to get to the hotel to sleep, another hour-and-a-half to get back. That's not eight hours of sleep, that's four-and-a-half hours of sleep."