by Gary Crump, AOPADirector, Medical Certification
Fatigue is one of those terms that we use often in normal conversation, yet, if really asked, we might not be able to accurately define it. If we're into free weight training, we do repetitions to “muscle fatigue and exhaustion,” meaning until we can't do another one. If we sit at the computer all day, we often complain of fatigue in the sense of physical tiredness and mental exhaustion. And true physical fatigue may set in on Saturday night after the first weekend day of yard work in the spring.
Fatigue in the aviation world, though, includes a whole constellation (as it’s referred to in medical-speak) of symptoms that boil down to what often ends up as a causal factor in the investigation reports of aircraft accidents, often called pilot error. It’s pretty clear that fatigue plays a role in many accidents, but it’s rarely, if ever, the smoking gun explanation for many aviation accidents. Illness, dehydration and poor diet, high humidity and temperature, disruption of circadian rhythms, and jet lag are just a few of the factors that can conspire against us.
The following articles demonstrate all too clearly the role that rest, and lack of it, plays in flying airplanes.
Accident Analysis: Asleep at the yoke By AOPA Air Safety Institute June 19, 2012 Fatigue is a subtle but insidious condition that can affect pilots in a variety of ways. It can degrade vision and coordination, dull memory and concentration, and alter mood and judgment.
New ATC scheduling aimed at combating fatigue By AOPA ePublishing staff April 19, 2011 The FAA and Department of Transportation announced changes to air traffic controller scheduling April 17 that are intended to give controllers more time to rest between shifts.
Fatigue and the GA pilot: Fatigue remains a top flight hazard By AOPA Publishing staff January 13, 2009 Fatigue would seem one of the easiest hazards for pilots to avoid—but it has proven one of the most difficult. Even multi-crew airliners with mandated rest periods have succumbed to fatigue in accidents over the years. And general aviation pilots face myriad business and personal stresses that can tire us out, mentally and physically, and harm our performance in the cockpit.
Fighting Fatigue By AOPA Air Safety Institute December, 2008 In this Safety Brief, we’ll look at some of the things that can lead to fatigue, and some steps you can take to keep it from catching up with you in the cockpit.
Safety Pilot Tired? By Bruce Landsberg AOPA Pilot, May 2006 You can't see fatigue, although the eyes may be bloodshot or the posture stooped. You can't smell it, and there are no traces in the body after a fatal accident like with drugs, alcohol, or carbon monoxide. Yet we've all experienced fatigue while flying or driving. We might think of ourselves as machines, but the reality is that our skill and energy levels vary from day to day.
Fighting Fatigue How not to fall asleep at the stick By Vincent Czaplyski AOPA Pilot, December 2005 What did the Chernobyl and Three Mile Island nuclear accidents, the space shuttle Challenger explosion, and the Exxon Valdez grounding have in common? Answer: The official investigations in each case determined that fatigue played a causal or contributory role in the outcome. According to Mark Rosekind, a leading expert on fatigue and alertness, accidents like these are especially dramatic examples of what can happen when humans become fatigued. But each year thousands of other less spectacular accidents occur across a range of activities, a by-product of a 24/7 world where sleep loss and circadian disruption are the norm for many individuals.
Tuckered Out Heed the warning signs of fatigue By Chip Wright AOPA Pilot, September 2004 When I first started this work, I didn't realize how tiring it could be. I thought I understood, but I was wrong. Dehydration was a serious issue. So was general fatigue.
Too Tired to Fly? Lessons in sleep deprivation from Lindbergh and the crew of Voyager By Bruce W. Frazer AOPA Pilot, May 2001 Sleep deprivation, often trivialized or ignored by pilots, nearly brought down two of the most famous aircraft in the world: the Spirit of St. Louis (1927) and Voyager (1986). The thoroughness of the flight planning seemed almost obsessive; to reduce weight and extend range, Lindbergh trimmed the edges from his charts, and one of the Voyager pilots, Jeana Yeager, clipped off her long tresses. But although these pilots had previously experienced the devastating effects of sleeplessness, they put the originally proposed countermeasures on the back burner — and they paid dearly for it.
Pilotage: Fatigue and the single pilot By Mark R. Twombly AOPA Pilot, June 2000 My laptop computer and handheld electronic personal organizer have a distinct design advantage over their operator: Each sounds a warning when the battery charge wanes to a critically low state. We pilots have no such definitive monitoring and annunciation feature to alert us to the imminent onset of a potentially dangerous low-power condition: fatigue.
Features: Too Pooped To Party By Budd Davisson AOPA Flight Training, April 2000 Fatigue is something that isn't talked about very much in aviation circles. In fact, it's one of those nonquantifiable factors that, if it left some sort of traceable residue during autopsies, would probably come out as a contributing factor to a lot of accidents. Instead, it is hidden as an accident cause because it is lumped into that well-known category, "pilot error." Yes, its true that the pilot made a mistake either in skill or judgment, but we'll never know for sure how much of a role fatigue played in that mistake.
Proficient Pilot: Cockpit catnaps By Barry Schiff AOPA Pilot, August 1999 Much could be written about the wide variety of conditions and scenarios that lead to acute fatigue. I doubt that there is an airline pilot alive who hasn't at least propped his head with a hand to prevent it from falling while "resting his eyes," a common cockpit ritual that takes place during the relative calm of cruise flight. The other pilot mans the helm, comforted by the knowledge that his turn will come.
Commentary: Out of the Pattern: The longest cross-countries Toughing It Out By Amy Laboda AOPA Flight Training, May 1999 As a flight instructor, one of my most difficult tasks is teaching students about the insidious, dangerous nature of fatigue. The required dual cross-countries aren't long enough to create fatigue, and it's not economically feasible for most students to carry out, say, a six-hour dual cross-country at night as part of their training. On the other hand, there's nothing to stop those same students from conducting the same cross-country trip with the ink still wet on their private pilot certificates. Nothing, that is, except good judgment and awareness of what might happen if they get too tired.
Commentary: Out Of The Pattern: Too Pooped To Fly? By Amy Laboda AOPA Flight Training, October 1997 Fatigue — it's got a grip on me right now. Two days of roaming central Florida theme parks on 95-degree afternoons has left me with wobbly knees, a woozy head, and throbbing temples. In the cab on the way back to the airport I gulp down two 24-ounce containers of pure spring water. The throbbing at my temples eases, and yes, sitting has definitely helped my knees, though I sense them stiffening up in the freon-induced cool of the car's interior. I'm definitely feeling the worst effects of dehydration passing, though.
New Pilot: A Stranger in the Cockpit You're not really you today...so who's flying the airplane? By Dan Namowitz AOPA Pilot, June 1994 If this were a video presentation, I would now freeze the frame and step to the podium to make the comment that the two pilots whose woes we have just witnessed are among the best I have flown with — good, smart, safe pilots who can handle tough in-flight situations. What the unfortunate antics depicted above demonstrate is that even good pilots can find themselves overmatched by an insidious enemy that is always waiting for a pilot to let his guard down. On the days in question, one pilot was very tired and the other overstressed when they climbed into their airplanes. They should have canceled their flights, but instead, at the end of a long day of work, domestic errands, driving the kids to Little League, and generally rushing around like mad, they had worn themselves down below a safe threshold for piloting an airplane—but didn't realize it.
Departments: Instructor Tips: "Why Marlin? Why?" By Mike Zonnefeld AOPA Flight Training, July 1993 Asking what happened, the examiner said: "The ground review went acceptably well. But when we got in the airplane, he didn't turn on any of the navigation receivers, and he was hopelessly lost shortly after takeoff. I was surprised that he'd take off this way on any flight, much less an instrument checkride. I failed him, of course, and we returned to the airport. Asking some questions while I was filling out his pink slip, he said he'd landed at 4 a.m. alter a 6-hour flight home. Mike, his checkride started at 7 a.m.! I had to agree that he was tired."
Departments: Medical Briefing Flying Fatigued By Jeffrey L. Nelson AOPA Flight Training, May 1992 Fatigue is one of life's unpleasant feelings. Most, if not all pilots will experience fatigue, but it's difficult to quantify afterwards how affected you were. There are many causes of fatigue: lack of sleep, hypoxia, noise, jet lag, temperature extremes, etc. But how does fatigue affect you? Do you really remember specifics days and weeks after the fact?