What's Classified As Error Could Be Avoidable Fatigue
By ANN Contributor Steven Lund
Following a
Congressional request in 1980, the NASA Ames Research Center
created an on-going program to examine whether "there is a safety
problem of uncertain magnitude, due to transmeridian flying and a
potential problem due to fatigue in association with various
factors found in air transport operations." Such as: flying
across numerous time zones.
Reporting in a Hearing on pilot fatigue, before the Aviation
Subcommittee of the US House of Representatives' Committee on
Transportation and Infrastructure in the summer of 1999 NASA's
Deputy Associate Administrator, Office of Aero-Space Technology
said "The NASA Ames Fatigue/Jet Lag Program (now the Fatigue
Countermeasures Program)… was created to collect systematic,
scientific information on fatigue, sleep, performance in flight
operations, and circadian rhythms-the biological "time clock" that
regulates the body's daily sleep-wake patterns NASA
established three program goals, which continue to guide research
efforts to:
- Determine the extent of fatigue, sleep loss and circadian
disruption in flight operations.
- Determine the impact of these factors on flight crew
performance.
- Develop and evaluate countermeasures to mitigate the adverse
effects of these factors and maximize flight crew performance and
alertness."
The NASA Program
gathered data regarding the existence and extent of fatigue in
aviation from several realistic sources, including actual flying,
laboratory studies, high fidelity simulations, and surveys.
These data have been consistent in showing that fatigue is an issue
with complex, diverse causes and potentially critical consequences.
Field studies specific to different aviation environments and using
a range of measures (e.g., performance, physiology, and behavior)
have revealed a number of factors related to fatigue. For example,
in long-haul operations, the non-24-hr duty/rest cycles, the
circadian desynchronization associated with transmeridian flights,
and the sleep loss accompanying night-time flying are all
associated with fatigue.
It has been evident, throughout this research program, that
pilot fatigue is a significant safety issue in aviation. Rather
than simply being a mental state that can be willed away or
overcome through motivation or discipline, fatigue is rooted in
physiological mechanisms related to sleep, sleep loss, and
circadian rhythms. These mechanisms are at work in flight crews no
less than others who need to remain vigilant despite long duty
days, transmeridian travel, and working at night when the body is
programmed for sleep.
A dramatic example of fatigue in U.S. aviation operations showed
up when NASA researchers collaborated with NTSB investigators in
assessing whether fatigue was present in the 1993 crash of a U.S.
DC-8 freighter in Guantanamo Bay, Cuba [Mentioned in Tuesday's
article].
NASA concluded that fatigue is a problem with diverse causes,
requiring a multi-faceted and comprehensive yet integrated
approach. Based on current research, such an approach should have
at least the following components:
- education and training
- hours of service
- sound scheduling practices
- effective countermeasures
- incorporation of appropriate design and technologies
- research
A NASA/FAA countermeasure study empirically demonstrated the
effectiveness of a planned cockpit rest period in improving
performance and alertness in long-haul flight operations.
Flight crews who were provided a planned 40-minute nap opportunity
(resulting in an average of 26 minutes of sleep) subsequently
exhibited improved physiological alertness and performance compared
to flight crews not receiving the nap opportunity.
The crewmembers napped
one-at-a-time in a three-person cockpit with minimal disruption to
normal flight operations and no reported or identified concerns
regarding safety. The benefits of the nap were observed throughout
the critical descent, approach and landing phases of flight. The
planned nap appeared to provide effective and acute relief from
significant sleepiness experienced by crews in three-person flight
operations
Technology continues to evolve rapidly, but humans have not
changed their need for sleep, their rate of adjustment after
circadian desynchronization, or the relationship between fatigue
and performance. Good system design incorporates information about
human physiology, its limitations and strengths, early in the
process. Technological approaches that use this information can
take many forms, including flight crew scheduling algorithms (i.e.,
the methodology of choosing flight crews) and alertness
monitoring/management systems. Fatigue Program work in this area
includes a project examining on-board crew rest facilities to
determine the quantity and quality of sleep obtained and the
factors that promote or reduce good sleep in the bunk.
Onboard bunks are used in operations with extra (augmented) flight
crewmembers onboard so that crews can rotate through flight deck
positions and non-flying crew can obtain sleep during long
flights.
A current NASA study is examining the feasibility of a
video-based, automated, online system for drowsiness detection on
the flight deck. Because we tend to underestimate our own degree of
sleepiness, these systems have the potential to play a valuable
role in detecting dangerous levels of fatigue and alerting
crewmembers to their presence.
However, once crews are
alerted to the presence of fatigue, the next problem is what can be
done to ameliorate it? Does the industry mandate that a
fatigued pilot immediately enter into a regiment of "power naps" --
designed to provide restful sleep, without negative post nap
effects such as grogginess, disorientation, or headaches? Or,
should airlines be required to constantly provide backup crew
members to replace ones with detected levels of fatigue? Both
of which would be required if modern flight decks were fitted with
drowsiness detection devices. Clearly not an incentive for
the industry to mandate such devices: Why measure a condition
for which there is no established mitigating procedure if the
Pilot's "Drowsiness Hi" light comes ON at the top of
descent?
The most viable solution would be that the industry require
pilots be adequately rested before the flight operations they are
scheduled to work; giving due consideration to the quality of rest
obtained, including their rate of adjustment after circadian
desynchronization in addition to the current Federal Air
Regulations (FARs) concerning crew duty cycles!
Considerable progress has been made during the last half of the
20th Century regarding knowledge about sleep, sleep need, the
effects of sleep loss on performance, and related issues. Even more
recently, major advances have occurred in human circadian rhythms
research, leading to an improved understanding of these daily
rhythms and their control by the human circadian pacemaker in the
brain . However, the NASA studies concluded that more
research is needed to fully understand the capabilities and
limitations of the human sleep and circadian systems. An additional
challenge is the appropriate application of this research to
operational environments such as aviation. Given the recent
development of technologies claiming to be able to detect fatigue,
focused research is needed to ascertain the sensitivity,
reliability, and validity of these devices.
According to NASA, research also needs to continue to address
regulatory, scheduling and countermeasure questions. The area of
fatigue is plagued by misconceptions about its causes and
characteristics. There is no substitute for valid empirical data to
guide decision making and policy.
Accident Investigation Strategies
If there is any question about "Pilot Performance" being an
issue in the chain of events leading to an accident, the Human
Factors Group should attempt to document the quality of the Crew
rest experienced by the Pilots in addition to determining adherence
to the appropriate flight and duty time regulations. For
instance, did the pilot experience any sleep disorders, such as
Insomnia or sleep apnea [caused by relaxation of the muscles of the
tongue and the soft palate at the base of the throat, allows the
breathing passage to collapse in individuals with a narrow airway.
Although chest movements may continue, no air flows into the lungs
and oxygen levels in the blood decrease. When blood oxygen levels
fall too low, the person briefly wakes to take a breath.
This cycle of sleeping,
then, the repeating cycle of airway collapsing, waking, and
sleeping, often occurs hundreds of times in a night. Individuals
with this common sleep apnea might not remember these brief
awakenings and believe they slept through the night. However,
the interrupted sleep leaves the individual exhausted in the
morning and sleepy throughout the day]. Even something as
innocuous as trying to rest in a noisy hotel room replete with
interruptions to the normal sleep cycle should be documented.
(Steven R. Lund is the retired director of flight safety
investigations in flight operations for the Douglas Products
Division of the Boeing Commercial Airplane Group in Long Beach,
California. He has spent over 36 years in the U.S. aerospace
industry, the last 32 of which have been at the Douglas Aircraft
Company (now Boeing). His entire career at Douglas/Boeing has been
devoted to flight test, flight safety, and commercial jet transport
incident and accident investigation. --
ed.)