Crew fatigue a major concern in bizav
Usually when we talk about fatigue, we speak about long flight hours with extensive exposure to sun and light changes and usually this is recognized as the detrimental consequences of long duty hours, especially long hours of wakefulness.
Around 1930, scientists began to appreciate the negative impact of rapid time zone transitions, making comparisons with people who were well-rested. People who are sleep deprived think and move more slowly, make more mistakes and have more memory difficulties. Now if we just apply this to the cockpit, we usually have two individuals who are sleep deprived and whose biorhythms oscillate in different ways. This is due to differences in weight, height and level of fitness.
This all boils down to the endocrinological experiences – the so-called circadian effect. “Circadian or effect rhythms” are physiological and behavioural processes, such as sleep-wake rhythm, digestion, hormone secretion, and activity, that oscillate on a 24-hour basis. Each rhythm has a peak and a low point during every day/night cycle. Time cues, called “zeitgebers,” keep the circadian “clock” set to the appropriate time of day. Common zeitgebers include daylight, meals and work/rest schedules.
If the circadian clock is moved to a different schedule, for example when crossing time zones or changing from a day work shift to a night shift, the resulting “sleep phase shift” requires a certain amount of time to adjust to the new schedule. The amount of time depends on the number of hours the schedule is shifted, and the direction of the shift. During this transition, the circadian rhythm disruption or “jet lag” can produce effects similar to those of sleep loss.
Transmeridian flights in excess of three time zones can result in significant circadian rhythm disruption. When flying in a westerly direction, the pilot’s day is lengthened. When flying east, against the direction of the sun, the pilot’s day is shortened. Thus the physiological time and local time can vary by several hours. Symptoms of jet lag are usually worse when flying from west to east as the day is artificially shortened. It takes about one day for every time zone crossed to recover from jet lag. When circadian disruption and sleep loss occur together, the adverse effects of each are compounded.
Reason for flight fatigue
Scheduling of adequate crew rest needs to take several important factors into consideration. These include: time since waking, time on task, type of tasks, extensions of normal duty periods, and cumulative duty times.
The “time since waking” is the starting point for fatigue to build. This can be prolonged for a variety of reasons prior to flying like wakening early due to disturbances in the sleep environment; the extra time needed to get up; the added time to check out of a hotel and travel to the airport for flight check in; a delay in getting preflight procedures started and mechanical problems or weather delays.
“Time on task” is the time required to preflight and fly. This is the time from check-in to block-in plus fifteen minutes on the last flight of the day. The “type of tasks” depend on the crew position, type of aircraft, and the nature of the flights. Extensions of normal duty periods can occur from events that prolong the flight longer than scheduled. Such events include delays for en route weather, rerouting due to traffic or, more rarely, diversions. Research on duty period duration suggests that duty periods greater than twelve hours are associated with a higher risk of errors. In determining maximum limits for extended duty periods, consideration needs to be given to all factors that contribute to fatigue including the numbers of legs in the day’s flight plan; whether jet lag is a factor in the crew duty day and the time since waking.
“Cumulative duty times” are most fatiguing when there are consecutive flying days with minimal or near minimal crew rest periods. This can result in sleep debt that requires additional time to overcome, and the fact that the body slows down due to it being early morning time.
Bizav especially susceptible to fatigue
All these factors show fatigue. Luckily we do work against this to help pilots and crews to cope with it, and we have also made big progress in our industry on this. But the fatigue we have in Business Aviation is a special fatigue caused by being with the same people for very long, extended periods of time. This means flying with the same crew for years and having the same passengers.
I am currently working on a study to get this phenomenon documented using reliable data to prove what effect it has. Strong conformity among the crew works completely against all positive forms of CRM. It takes a lot to write a report on someone who made a mistake when you have just spent the last three weeks with him or her on a small Caribbean island waiting every day for your passengers.
As early as the 19th century, with the pending industrial revolution, Nietzsche (1878) warned that a machine culture would cause boredom for workers, resulting in human “play” at work. More than 130 years later, the news is replete with examples of just such a phenomenon. In 2009, during the enroute portion of a flight, two Northwest pilots were reportedly distracted by their laptops causing them to overfly Minneapolis by 90 minutes (“Northwest Airlines Flight 188,” 2009). In 2011, an air traffic controller and a supervisor were suspended after it was discovered that the controller was watching movies in the early morning hours under reported light traffic conditions. While ultimately distraction was the direct cause of operator misbehavior in these cases, the under-stimulating low task load had a major effect on it.
Boredom, monotony and hypovigilance are the drivers of fatigue in Business Aviation. All operators and training facilities need to address this and help make crews and companies aware of it and fight against the silent problem that affects all of us in various ways.
Dagmar Grossmann wanted a life in fashion. She instead has devoted her career to the aviation industry, as CEO of Grossmann Jet Service and founder of the Central Europe Private Aviation (CEPA) EXPO.