When fatigue increases for pilots, their reflexes and motor responses in the cockpit slow significantly, Hudson said.
They become complacent in accepting lower standards, and skills such as instrument cross-checks slow in speed and accuracy. Oral communication in the cockpit suffers and, of course, tired people may fall asleep, he said.
Pilots are flying longer hours daily, weekly and monthly, although still within federal regulations, said Continental Air Line Pilots Association head Dave Earnest, who lives in Fort Collins.
Jeff Kleymann, 45, a United Airlines pilot who lives in Morrison, said he recently worked a 13-hour day, which includes time in the cockpit and time between flights.
Fatigue became part of a debate over a federal rule that requires airline pilots to retire at age 60. Sixty-six percent of the pilots association members are over 40, although that union doesn't represent pilots at some of the smaller airlines with younger crews.
Pilot pay in the airline industry can range from less than $20,000 to well above $100,000.
Some pilots would like to work more years because of pension and wage cuts. But ALPA is not seeking a change to the law after polling its members.
"(Pilot fatigue) is more dangerous to any passenger in my opinion than age," said Sen. Ted Stevens, R-Alaska, during a subcommittee hearing last year on the age-60 rule.
JetBlue Airways Corp. has been reprimanded by the FAA for allowing pilots to fly more hours than regulations permit.
Sweeping rule overhauls commercial passenger airline pilot scheduling to ensure pilots have a longer opportunity for rest before they enter the cockpit
To call a vote, the board must certify that the Machinists collected signatures from at least 35 percent of the workers.
In a 24/7 industry like aviation, fatigue is a fact of life.