During a mid-August afternoon in 1993, American International Airways Flight 808 prepared to land in Guantanamo Bay. Procedures required that the pilot execute a visual approach over the sea that included a late right turn toward the runway, to avoid entering Cuban airspace, less than a mile to the west. The crew, who had been awake for over 19 hours continuously, overbanked the Douglas DC-8-61 freighter, lost control, and crashed. An investigation by the National Transportation Safety Board determined that the impaired decision-making demonstrated by the three crew members, all of whom were injured, was due to the debilitating effects of fatigue.
Today, fatigue remains a problem for pilots and a risk to the flying public, but incomplete science and the positive effect of aviation technology make the best solutions hard to see.
Managing fatigue hasn’t always been about preventing accidents. During the Industrial Revolution, long workdays prompted calls by social reformers for a more equal distribution between work, recreation and rest, calls that eventually led to the establishment of an eight-hour workday.
A century later, fatigue came under the scrutiny of scientists. NASA dedicated a research program to understanding the phenomenon amongst pilots. The effort was groundbreaking for its time, as researchers studied the effects of sleep loss and interruption on muscle activity and brain function. They found that when it came to alertness in the cockpit, the conditions in which pilots flew mattered as much as the time they spent at the controls. These findings facilitated a major change in how fatigue was managed on the flight deck.
Achieving the type of deep restorative sleep necessary to avoid fatigue requires that muscles relax, body temperature fall, and brain activity drop. Longer periods of rest between shifts gives the body the chance to do that. Limiting the total amount of flying required of pilots each month also reduces the chances of fatigue building up over consecutive work cycles.
In 2011, the Federal Aviation Administration (FAA) placed its strictest limits to date on night flying by commercial airline pilots, because working when the sun’s down is more fatiguing than doing the same during the day. US carriers must give their pilots longer rest opportunities prior to flying (ten hours compared to eight previously) and provide them 25 percent more continuous time off each month. Advocates contend that today’s rules improve safety. The Air Line Pilot’s Association, the world’s largest pilot union, lauded the new FAA rules as “a significant victory for safety and the traveling public.”
Such rules may seem great when it comes to keeping the skies safe, but it’s hard to know they are adequate. One problem is the lack of agreement among scientists as to what fatigue actually is. Some call it a process, others a state. Some treat it as being synonymous with sleepiness, others see it as a “moral disorder” that weakens willpower and leads to physical exhaustion.
Modern tools aren’t a perfect solution. New psychometrics tests can measure how alert a pilot is. “Actiwatches,” small wrist-worn devices, can record a flight engineer’s sleeping patterns for months at a time. Questionnaires gauge how tired crew members believe themselves to be. Yet, Dr. Atul Khullar, a fellow at the American Academy of Sleep Sciences points out, points out, “the extent to which these techniques accurately predict how safely an airplane is flown is less clear.”
It’s hard to be sure we’re addressing fatigue properly, because—ironically—commercial aviation’s remarkable safety record makes the answer hard to find. More than 37.6 million commercial flights took to the skies in 2015, a new record. The global accident rate—measured as the number of aircraft lost per one million flights—was just 0.32, one of the lowest in history. Long-term trend data suggests flying is getting even safer.
This rarity of accidents is a testament to technological progress, especially improvements in airframe construction, propulsion mechanics, and avionics design. It also means proving that fatigue reduces safety is difficult, because those technologies lessen the potential fallout. The highly automated nature of flying today means aircraft flown by weary pilots will almost certainly still reach their destinations safely.
Addressing these issues will not be easy, but it is necessary, because fatigue can make flying more dangerous. In its report on the 2007 crash of Colgan Air Flight 3407, which killed all 49 people aboard and one person on the ground, the NTSB found a variety of causes, and concluded that “the pilots’ performance was likely impaired because of fatigue.”
Even with better information on how to manage fatigue, those efforts face opposition from the industry because they add expenses to airline balance sheets that are already in the red. The 2011 FAA rules for example, forced carriers to hire more crew and place extra staff on reserve, to the tune of $300 million. That’s hardly chump change for an industry that saw a mere four percent profit (or $8.27 per passenger) the year the rules went into effect. As long as this continues, managing fatigue will continue being a prickly affair.