When most of us take a flight, we assume that our pilots and cockpit crew are rested and wide awake…but don't be so sure! According to a disturbing survey conducted by the British Airline Pilots' Association (BALPA) of 500 commercial pilots, more than half (56%) admitted being asleep during a flight, Reuters reported.

Even more alarming, almost a third (29%) of those pilots nodding off said that when they woke up, they found their co-pilot asleep too.

Pilot fatigue made headlines this week after two pilots fell asleep in the cockpit while operating an Airbus A330, leaving hundreds of passengers unsupervised. The members of the flight crew had only five hours sleep in two nights due to long duty periods working without a chance to rest, according to reports.

Moreover, an airline pilot suffered a midair heart attack aboard a United Airlines flight to Seattle yesterday and later died after the plane was forced to make an emergency landing in Idaho, NBC reported, although the cause of his heart attack has not been disclosed.

According to aviation safety expert, and one-time hero Captain Chesley Sullenberger, best known for his successful emergency landing in the Hudson River in 2009, pilot fatigue is a world-wide problem that is very serious and largely underreported because of the fear and perception amongst pilots that reports submitted have not been effectively acted upon:

“As airplanes make longer flights at all hours of the day or night, it’s predicable that because of fatigue short-term memory diminishes, awareness and alertness diminish, judgment and the mental energy necessary to intervene and act effectively diminishes and it's insidious because it is not obvious to pilots at the time that they are being as badly effected by fatigue as they are,” he told CBS News.

Yet, despite the magnitude of the problem, it seems our pilots at least in the United States have no choice but to work to the brink of exhaustion. According to a Reuters report, Air Transport Association – U.S airline’s top trade group – told the Obama administration that complying with regulations to combat pilot fatigue is impractical and would cost $2 billion a year and over time cut 27,000 jobs tied to the industry.