Fatigue and Alertness Management in Aviation

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Fatigue and Alertness Management in Aviation
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• Provide scientific-based recommendations for
  aircrew scheduling
• Five European teams working on the field of
  fatigue

KI
QinetiQ
TNO
DLR
LAA
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Contents

• Introduction and background
• The case of ultra-long-range flights
• The case of cockpit napping in two-pilot flights
• Discussion and recommendations
• Conclusion

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Contents

• Introduction and background
• The case of ultra-long-range flights
• The case of cockpit napping in two-pilot flights
• Discussion and recommendations
• Conclusion

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Introduction Fatigue in aviation

• Widely recognized as a main factor affecting
  performance of pilots
• Remains a key issue regarding ultra-long-range
  flights, commercial pressure in smaller airlines
• In the past years, fatigue studies have mostly
  focused on the individual level, the pilot
• Should be considered in a more systemic approach
• More emphasis should be placed on fatigue and
  operational performance

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Main causes of fatigue

• Two main factors
• Time since sleep
• Biological rhythms

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Some consequences of fatigue

• Micro-sleeps (sleepiness)
• Increased eye closure
• Longer reaction times
• Difficulty in solving problems
• Reduction in communications
• Difficulty in solving inter-personal conflicts

Flight New York Brussels
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A340 certifications flights
Cumulated number of microsleeps during the final
phase of the flight TLS-SFO-TLS and TLS-SIN-TLS
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Underestimation of sleepiness at the end of a car
trip
Perceived sleepiness (questionnaire)
of micro-sleeps
14
100
12
80
10
60
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Perceived sleepiness
Ratio ()
6
40
4
20
2
0
0
Awake
D
P1
P2
P3
F
4-hr trip
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Contents

• Introduction and background
• The case of ultra-long-range flights
• The case of cockpit napping in two-pilot flights
• Discussion and recommendations
• Conclusion

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The case of ULR flights SIN-LAX and SIN-NY
CAA Singapore Airbus ECASS University of Massey
(NZ)

• Three-step follow-up study
• Prediction
• Validation of predictions on current LR
  operations
• Validation of predictions on ULR

Around 17 hrs of flight time
Around 20 hrs of flight time
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Prediction of alertness for different flight
schedules

return flight starting at 1400
Outbound flight departing at 2000
Main Crew at Controls
6 hours
6 hours
Relief Crew at Controls
Based on conservative recuperative sleep
assumptions
The benchmark for lowest acceptable alertness
being 30
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Prediction of alertness for different flight
schedules
return flight starting at 0100
Main Crew at Controls
6 hours
Relief Crew at Controls
6 hours
The benchmark for lowest acceptable alertness is
30
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In-flight sleep duration

14
12
10
8
Percentage
6
4
2
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
Sleep time (hours)
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Fatigue evaluation during return flights
Very sleepy
9
8
Unacceptable zone
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Crew 1
6
5
Score
Crew 2
4
3
2
Very alert
1
0.00
4.00
8.00
12.00
16.00
20.00
24.00
Time (UTC)
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Percentage of pilots with a score gt 8
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Education and training
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SIN-CDG-SIN Short Layover
Before the flight - During the day normal
activity, exposure to daylight in the afternoon,
avoid coffee and tea after 16h. - Do not take a
nap during the day. - In the evening take a
light meal and go to bed as early as possible. -
In the morning if your rest during the flight
is planned in the first part of the flight, you
should limit your coffee and tea intake.
- If early wake-up, alertness decrement may occur
between 13h and 16h. - Alternate active and
passive phases. - Avoid taking your meals or
snacks at the same time as the other
crewmember. - Rest starts between 9h and
12h. This part of the flight is unfavourable for
sleep. You should plan a longer rest period or
divide your rest into two or three periods spread
out over the flight.
Upon arrival take a light meal.
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Contents

• Introduction and background
• The case of ultra-long-range flights
• The case of cockpit napping in two-pilot flights
• Discussion and recommendations
• Conclusion

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The case of cockpit napping in two-pilot crews

• Known as a widely used countermeasure against
  fatigue in long-haul flights
• Advantage reduces the number of microsleeps
  during the final phase of the flight and
  increases performance (Rosekind et al, 1994)
• Drawback Induces a risk of sleep inertia upon
  waking up (Naitoh, 1981 Stone and Robertson,
  2001)

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Sleep inertia
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Sleep structure (normal)
Time
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Rapid Eye Movement
Stage 1
Light sleep
Stage 2
Stage 3
Deep sleep
Stage 4
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Countermeasure against sleep inertia (Air France
example)
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Method

• Flights
• 10 rosters (20 flights) on A340 (SABENA)
• Two-pilot crew
• Brussels - New York
• Schedule (base time )
• outbound 19h30?03h30
• layover of 26 hrs 30
• return 06h00 ?13h00
• Aircrews were asked to take preplanned rest of 40
  min (aural warning)

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Sleep stages duration during 40 min in-flight
naps
Deep sleep
Max 23.5
Max 14.5
n number of pilots
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Sleep stages and alertness during flights
New-York -gt Brussels - Capt
Awake
GMT
Preplanned rest
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Contents

• Introduction and background
• The case of ultra-long-range flights
• The case of cockpit napping in two-pilot flights
• Discussion and recommendations
• Conclusion

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Discussion

• High individual variability
• Sleep patterns during cockpit napping depend on
• previous sleep time
• time of the day
• In some cases, napping is not sufficient to
  alleviate sleepiness
• Even limited to 40 min, nap may contain deep
  sleep stages

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Discussion and recommendations

• Napping strategies in two-pilot flights should
• take into account time of the day and previous
  sleep loss
• be pre-planned by the aircrew, taking into
  account their initial fatigue
• be followed by a relief period (around 20 min) to
  allow sleep inertia to be overcome
• Additional research is needed
• to support recommendations and environmental
  countermeasures (e.g. light)
• to look at the relationship between fatigue and
  operational performance

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Conclusion
A systemic approach of fatigue in aviation the
Swiss Cheese model
Adapted from Reason,1990