Medical Issues in Aviation

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Medical Issues in Aviation
Lima, Peru March 2009
Flight Crew, Circadian Rhythms, Fatigue,
Alertness Long Haul Opearations
Dr. Jarnail Singh Civil Aviation Authority of
Singapore
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• Fatigue and alertness
• Rest and sleep
• Time since awake
• Type of activity
• Time on task
• Type of task
• Circadian rhythm
• Drugs/Medication/Aids to alertness

• Manual
• Mental

• Monotony/Boredom
• Challenging

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Measuring Fatigue
Fatigued Get Out
Wouldn't it be nice?
Fatigue Meter
ALERT
BUSHED
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Can Fatigue be measured?
Physical Yes
Mental No
Research Ongoing -- US Navy Studies
Alcohol Equivalence Caution!!! In Using Such
measures
Surrogate Measures eg. Karolinska / Stanford
Scales
Concept of AVOIDANCE of Fatigue
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Can Alertness Be Measured?
Sleep Vs Wakefulness -- EEG (Polysomnography)

• Psychomotor Vigilance Tests
• Simple Reaction Time
• Choice Reaction Time
• Tracking Tasks
• etc

Performance Based Measures LOSA, FOQA etc
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Yerkes-Dodson Curve
OPTIMUM
Acceptable
GOOD
Performance
POOR
POOR
LOW
HIGH
Arousal Stress Workload etc.
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Yerkes-Dodson Curve
Acceptable
Performance
GOOD
Arousal Stress Workload etc.
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Yerkes-Dodson Curve
Shift to the Right
OPTIMUM
Well Rested
GOOD
Good Sleep
Good Handle on Life Stressors Etc..
Acceptable
Performance
POOR
POOR
LOW
HIGH
Arousal Stress Workload etc.
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Yerkes-Dodson Curve
Shift to the Left

• Not Slept Well
• Not Well Rested
• Circadian Desynchrony Not Managed
• Work Overload
• Excess Alcohol

OPTIMUM
GOOD
Acceptable
Performance
POOR
POOR
LOW
HIGH
Arousal Stress Workload etc.
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General Idea
Build up reserves
Spare mental capacity
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NOT a good example of a person with reserves and
spare mental capacity
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In the Aviation World
Rest Sleep
Circadian Desynchrony
?
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Time Since Awake
Sleep
Awake
In - Between
Take - Off
0800
2000
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Yerkes-Dodson Curve
Which Side of the Curve are you on?

• Right

OPTIMUM
GOOD
Acceptable
Performance

• Left

POOR
POOR
LOW
HIGH
Arousal Stress Workload etc.
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TYPE OF ACTIVITY
Vs
PHYSICAL
MENTAL
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Time On Task
Remember Yerkes-Dodson!
Type Of Task
Cockpit Environment
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Flight Time Limits...
.... in Aviation
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A
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B
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• Factors that moderate alertness/fatigue on the
  flight deck
• Number of flight crew
• Composition of flight crew
• Status of circadian acclimatization
• Previous duty duration
• Opportunity for pre-flight rest/sleep
• Opportunity for in-flight rest/sleep
• Post-flight recovery and sleep

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Ultra Long Range Flights
What were the issues to be resolved?
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B
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Lessons From ULR Studies
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Departure windows that factor in circadian shifts
and a systematically thought out plan for
rest/sleep in the overall duty cycle, alongside
appropriate crewing, are the key to maintaining
alertness.
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Aids To Sleep Alertness
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Alertness
Sleep zzzzzzzzzz
Relaxation
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Aids to Alertness
COFFEE
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Time of Consumption and Amount Consumed are
Important
Coffee
Within the Duty / Rest Cycle
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Sleeping Aids
What a coincidence, so does he
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Melatonin
Hormone produced mainly in Pineal gland Regulates
circadian rhythm in the normal dark/light cycle
?Assist in jet-lag Should a pilot use it? When to
use it
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Hypnotics.....Zzzzzzzzzzzz
What are they?
Dose
Tranquility
Sleep
Death
Unconscious
Pilots ---- ? Take Hypnotics
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What about Alcohol?
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NOT a good
Sleeping aid !
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Sleep Hygiene...zzzzzzzz
Humans (like all animals) are creatures of
habit Establish sleep habits --- follow the
routine
Healthy Life Style Essential
Moderation is the key
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Sleep structure across the ages
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The Bedroom.....
HOTEL
HOME
.... for sleep only
..... For Sleep Only
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OK, Provided You
Get Some Sleep As Well !!
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Definitely Not Recommended
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Zeitgerbers
Entrain the Circadian clock
eg. Light vs Dark
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Hygiene Factors ?
Up to a limit
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"Avoidance" of Fatigue
CAP 371
We know the factors leading to fatigue.
Fatigue is difficult to quantify
Cut-off points for fatigue cannot be determined
Avoidance of Fatigue Factors is the BEST Bet
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Proponents of
Fatigue Risk Management
Are Saying The Same Thing
It Is Just Packaged Differently
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Summary

• Fatigue remains a problem among pilots
• Regulators, Pilots and Airline Operators all have
  a part to play
• Current regulations (FTLs) require revision
• Definitions within the regulations need to be
  crafted/refined to remove ambiguity (of
  interpretation)
• Overarching prescriptive limits likely to remain
• Fatigue Risk Management will come in within the
  ambit of the overarching prescriptive limits

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