The Yoke of Fatigue

Cockpit fatigue can creep-up undetected. It's important to understand this potential killer and know how to defeat it.

Dave Higdon  |  09th January 2014
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Dave Higdon
Dave Higdon

Dave Higdon is a highly respected, NBAA Gold Wing award-winning aviation journalist who has covered all...

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Cockpit Fatigue Topic Resurrected by FAA Top Doc

Raise your hand if you've never nodded off flying back home after a long day of travel punctuated by interrupted sleep patterns and irregular mealtimes. Nobody? Not to worry – happens to the most-seasoned of business road warriors, in cabs en route to the airport; on Airliners; in private aircraft. So imagine the challenge for flight crews supporting your travels.

Do you think they get good rest during those “standby time” periods when you're laboring away at the business of the day? Maybe... when they’re not prepping for the next leg of the trip; attending to the aircraft refueling and re-provisioning; briefing the weather; filing their flight plans and checking in with the company dispatcher or home base - whichever applies.

The crew often turns in last and rises first on schedules driven by the needs of those traveling in the back cabin. And when finally at work, attending to the aircraft, even those periods create challenges to human circadian rhythms, with periods of intense focus and steady action sandwiching an expended and irregular period of doing little more than monitoring computer systems, answering occasional radio calls and, for the most part, passively engaged in “turning a knob here or pushing a button there”.

When you stop and consider the routine, you’ll understand that the flight crews face the same fatigue-inducing challenges as most of the passengers: long days of travel punctuated by interrupted sleep patterns, time-zone shifts, irregular mealtimes and unproductive rest periods often at strange hotels. Thus it is little wonder that one of mankind's oldest challenges manifests itself too often in aircraft cockpits: Fatigue, and the risks it imposes on its sufferers.

However, just as companies and safety authorities finally start to apply measures they recognize will fight fatigue and its insidious effects, the chief air surgeon of the Federal Aviation Administration raised the specter of imposing a new medical standard he says will help avert fatigue where there was no prior record of the condition creating an unsafe situation in aircraft cockpits.

The issue can be of particular concern in single-pilot operations, where no second-in-command pilot exists to work with the pilot-in-command...

The Wages of Fatigue

According to “Fatigue in Aviation”, an FAA pilot-safety brochure of medical facts for pilots, fatigue:
• Is characterized by increased physical discomfort;
• Manufactures a lessened capacity for work;
• Leads to reduced efficiency of accomplishment; and
• Creates a loss of capacity to respond to stimulation.

No wonder fatigue also brings on feelings of “weariness and tiredness.” The body is tired – and the brain suffers from the physical lack of rest, even when ‘jazzed’ by stimulant beverages.

Far from being an abstract concept, ample evidence exists of fatigue's impact. A case study exists of a business jet crew who showed signs of fatigue through a bout of cockpit confusion that had the two pilots acting in opposition to one another after each had separately misunderstood the other – and controllers' instructions.

Another features an Airliner crew that over-ran their landing runway, badly damaging the Airliner they were flying. The investigation concluded that fatigue contributed to the crew's failure to calculate properly its runway needs that snowy April day. After fussy mental states kept the pilots from performing routine runway calculations their rest-deprived state contributed to their slow awakening to their situation. Fortunately, the event caused no injuries to the 49 passengers, two pilots and a flight attendant.

The pilots of another Airliner over-flew its destination by many minutes and miles. The cockpit voice tapes helped confirm that the flight crew had nodded off for an ad hoc nap when they should have been descending for an approach into the airport they flew past. Fortunately, the two pilots ultimately awoke from their involuntary slumbers, returned to the intended destination and landed normally – though lighter on fuel than usual.

No Harm, No Foul...Right?

Not so fast. Each save portends the potential for the fatigue-inspired event to become injurious, even deadly. And we're addressing only a scant few well-known incidents. Evidence shows the occurrence of far more fatigue-related events than these well-publicized few. NASA's Aviation Safety Reporting Service and its CallBack newsletter regularly relates pilots' tales of close calls stemming from them flying too tired for safety's sake.

Only survivors who came up short of causing damage or incurring injury are eligible to file a report with the ASRS, for which they can get a pass on many enforceable events. What makes fatigue a special challenge arises from its impact on both the pilot and the party responsible for weighing a pilot's readiness for duty... Yes, that same pilot.

Pilot, Heal Thyself...

According to the FAA, medical specialists and fatigue researchers, the one person least able to judge a pilot's readiness is the fatigued pilot themselves. Put simply, the individual aviator is neither capable of reliably diagnosing the degree of fatigue felt nor judge the degree of impairment resulting from that fatigue. To make matters more challenging, fellow crew may be in no better a position to judge the impact of others' fatigue.

Adding to the complication can be the time of year and the hemisphere flown in, melatonin levels in the body, and the amount of sunshine available – which can flip in a day flying from one side of the equator to another. Let’s not neglect Seasonal Affective Disorder, which works its own dark magic on the human body when the days reach their shortest.

True, summer's long days can exacerbate fatigue problems because of the prevalence of daylight, but winter's long nights can contribute to the challenge of staying awake and alert in the cockpit. Even down in the Lower 48 work days can start hours before sunrise and continue well past sunset, not even allowing for a time-zone shift.

With days ranging from a maximum of about 10 hours, 30 minutes, to a minimum of 8 hours, 45 minutes in the Continental U.S., and the ability to move multiple time zones in a couple of hours, there’s no wonder crew and passengers struggle with their work, rest and sleep routines. Fatigue, it seems, has a particular penchant for a perverse impact on pilots. Since private aviation operations aren't regulatory-bound to follow pilot rest rules as Airline and charter pilots must, the question becomes one of finding ways to identify and obviate the occurrence of any fatigue-related events.

FAA AC-120-103 Start-Point

With so many factors in play the question inevitably becomes one of finding a way to judge when a pilot goes beyond tired into fatigue – and where fatigue results in pilot impairment. Start with the acknowledged factors contributing:

• The amount, timing and quality of daily sleep (i.e. the sleep/wake schedule with an assessment of the quality of the sleep);
• The time elapsed since the last sleep period (i.e. the length of time the pilot has been awake);
• Time of day/circadian rhythm; and
• The workload and time on task.

Out of this a crew can use a data-based system to mitigate the possibility of a pilot spending too long on duty with too little rest... at least, to the extent that a pilot's flying day is controllable and predictable. A company's Safety Management System can provide the foundation for company-wide policy and practices designed to avert situations that produce a pilot who is too fatigued to be safe.

That approach, however, is of little help to the single-plane operation staffed by one or two pilots – or by an owner/pilot operator. And in some ways, experts stress, the different ebb and flow of corporate flying can challenge the demands of scheduled flying – particularly when (a) schedules go out the window for both types of flying and (b) pressure builds to complete the day's flying.

For the commercial pilots there are new Part 117 rules scheduled that go into effect on January 4, 2014. For Business and General Aviation, there's only common sense and a strong sense of self-preservation and self-regulation to deploy. The FAA's guidance is available on-line in Advisory Circular 120-103:

The Aviation Fatigue Meter

Electronic Flight Bag users, tablet totters and smartphone fans saw plenty of new products and tools debuted at the 2013 National Business Aviation Association but one in particular aims to expand its role as a fatigue-mitigation tool by moving into Business Aviation.

Pulsar Informatics showed off a free beta version of its new crew fatigue evaluation web application: the Aviation Fatigue Meter. The application works for every type of Business Aviation operation, Pulsar said, regardless of its size, scale, or how complex the operation may – or may not – be. The appeal is its easily interpreted method of showing how any particular schedule is impacted by human fatigue factors.

The ten-year-old company already has a track record for developing fatigue-assessment tools for the National Aeronautics and Space Administration (NASA), the Department of Transportation (DoT), and the Defense Department (DoD), for workers ranging from astronauts to surgeons. Previous users of the company's fatigue-assessment tools include such schedule-challenged workers as truck drivers, submariners aboard U.S. Navy nuclear boats and astronauts on the International Space Station.

This program was still available for free at as of this writing. The company continues to work on its effort to massage the program into something useful and effective for the Business Aviation community, building on the programs already written for those previously mentioned areas.

Such a tool could not only help flight departments and pilots better assess their fitness to fly, but the tool could also be helpful when the need arises to enlighten passengers and bosses why a crew is exercising a captain's prerogative and standing down for a good night's sleep.

After all, it's not as if anyone is immune, and the pilot who refuses to face the fatigue is a candidate to have it surprise him upon waking from an unwelcome cat nap.


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