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Sim Trans 22. April 2010

Sim Trans 22. April 2010. Flight Fatigue Knud Jessen. Charles Lindberg about his 1927 transatlantic flight. ”My mind clicks on and off. I try letting one eyelid close at a time..... but the effect is too much, the sleep is winning... nothing life can attain is so desirable as sleep.

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Sim Trans 22. April 2010

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  1. Sim Trans 22. April 2010 Flight Fatigue Knud Jessen

  2. Charles Lindbergabout his 1927 transatlantic flight ”My mind clicks on and off. I try letting one eyelid close at a time..... but the effect is too much, the sleep is winning... nothing life can attain is so desirable as sleep. My mind is losing resolution and control.”

  3. Fatigue • Definition: a non-pathological state resulting in a decreased ability to maintain function or workload due to mental or physical stress

  4. Big Problem Expert consensus is that fatigue is ”the largest identifiable and preventable cause of accidents in transport operations” (Åkerstedt, Carolinska University Hospital, Sweden)

  5. Types of Fatigue • Local: muscular inability to carry on • General: felt aversion for exertion and overall inability to carry on • Generalized as applied to the whole body: - individuals feeling of discomfort and aversion - inner awareness of making mistakes - change of efforts required to carry on

  6. Types of Fatigue • Definition: A state of diminished physical and/or mental efficiency. • Types of Fatigue • Acute - Work induced • Chronic - Repeated sleep loss • Subjective - Stress-induced fatigue • Circadian rhythm - shift work & jet lag

  7. Fatigue and flying • Lack of patience • More forgetful • Instrument cross check breaks down • Reduced Situational Awareness • Slows reaction time • Reduced G tolerance • Micro-sleep

  8. Measurering fatigue • No biochemical markers for fatigue • no breathanalyzer • no blood component

  9. Flight Fatigue:- a significant, but often under-reported problem with considerable effect on flight safety! 1994: Wegmann , Deutsches Institut für Luft- und Raumfartmedizin 1998: Gander, NASA-Ames 2003: Bourgeois-Bougrine, Université René Descartes, Paris 2003: Strauss, NASA-Johnson Space Center 2003: Goode, FAA Washington DC 2005: Caldwell, USAF Research Lab Brooks 2006: Caldwell, Ernsting’s Aviation Medicine 2006: Åkerstedt, Karolinska Instituttet, Stockholm 2006: Jackson, Falculty of Health, University of Birmingham 2007: Powell, Air New Zealand 2007: Morad, Tel Aviv University 2007: Signal, Massey University, New Zealand Etc..etc...

  10. Flight Fatigue • 2007: Report by Moebus Aviation: Expert group of medical scientists evaluation of EU Subpart Q on flight time regulations

  11. Flight Fatigue • John Caldwell: Aircrew fatigue: Causes, Consequenses, Countermeasures Workshop at the Annual AsMA Scientific Meeting, Boston, May 2008 and Phoenix, May 2010.

  12. Awake Drowsy state REM Stage 1 Stage 2 Stage 3 Stage 4 1 2 3 4 5 6 7 8 HOURS Sleep Cycle

  13. Circadian RhythmsorInternal Circadian Clock • Circadian rhythms fluctuate over app. 24 h (free run) * Controlled by the suprachiasmatic nucleus in hypothalamus * Many body functions have their own rhythm over 24h synchronized by ‘zeit-gebers’ (e.g. light) * Moving to a new light/dark schedule (e.g. shift work or time zone change) can create desynchronization

  14. Circadian Rhythm - Efficiency mk/99

  15. Factors Affecting Sleepiness • Prior sleep/wakefulness • Age • Medical conditions • Medications • Alcohol • Environmental/work conditions • Circadian phase

  16. Measurements of presence and degree • * Category rating scales (subjective / questionnaires) • * Electrical registration of • heart activity (ECG) • brain activity (EEG) • eye movement (EOG) • body core temperature • measurement of blood- and urine content of enzymes and hormones

  17. Effect of Sleep Loss / Sleep Debt: Partial sleep loss (=/> 8 h / 24 h) is of less significance than Disturbed sleep in relation to a particular flight duty period Cumulative effect of Irregular work, Disturbed sleep, and Circadian desynchronizatioin

  18. Effect of Sleep Loss / Sleep Debt: Logarithmic relationship between total duty hours and number of operating days (Nicholson 1978) tdh of 40 h -> max of 3.6 d / opt. of 4.5 d tdh of 50 h -> max of 5.7 d / opt. of 6.8 d tdh of 60 h -> max of 8.4 d / opt. of 9.8 d

  19. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA):Crew Factors in Flight Operations:The Initial NASA-Ames Field Studies on Fatigue • FLIGHT CREW FATIGUE: I: Objectives and Methods II: Short-Haul Fixed-Wing Air Transport Operations III: North Sea Helicopter Air Transport Operations IV: Overnight Cargo Operations V: Long-Haul Air Transport Operations VI: A Synthesis -

  20. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue II:Short-Haul Fixed –Wing Air Transport Operations • 74 pilots on 3 days trip • Mean duty hours / day: 10.63 • Mean flight hours / day: 4.51 • Number of flighth segments / day: 5.51 • Mean night time layover: 12.45

  21. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue II:Short-Haul Fixed –Wing Air Transport Operations Slept less (accumulation) Awoke earlier Difficulty to fall asleep Lighter, less restful sleep Poorer overall sleep quality

  22. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue II:Short-Haul Fixed –Wing Air Transport Operations Subjective symptoms reported: Headache Congested nose Back pains

  23. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue II:Short-Haul Fixed –Wing Air Transport Operations More snacks than regular meals More caffeine More alcohol (”night cap” as relaxing means)

  24. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue II:Short-Haul Fixed –Wing Air Transport Operations Recommendations: Sleep loss should be reduced by including the duration of the duty day as a factor of the subsequent rest period Successive duty days should begin at the same time Better life style

  25. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue V:Long-Haul Fixed –Wing Air Transport Operations • 32 male pilots • monitored before, during and after • 4-9 days long-haul trips • crossing up to 8 time zones per 24h

  26. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue V:Long-Haul Fixed –Wing Air Transport Operations • Average duty day: 9.8 h • Average layover: 24.8 h • greater sleep loss associated during duty hours as well as during layover • circadian low point in alertness and performance occured in flight

  27. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue V:Long-Haul Fixed –Wing Air Transport Operations Subjective symptoms reported: Headache Congested nose Back pains

  28. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue V:Long-Haul Fixed –Wing Air Transport Operations More snacks than regular meals More caffeine More alcohol (”night cap” as relaxing means)

  29. Aviation, Space, & Environmental Medicine Sept. 1998:Gender et al. (NASA): Flight Crew Fatigue V:Long-Haul Fixed –Wing Air Transport Operations Recommendations: Crewmembers, schedulers, and regulators should be provided with education about sleep and circadian physiology together with practical information on countermeasures which they can tailor to their own needs and demands Better life style

  30. Wegmann, Institute of Aerospace Medicine, Germany, 1995: • 22 pilots flying 2 x 11 hours during 2 consecutive nights separated by 1 day sleep including 3 hours time zone difference • Measured by log registration of *fatigue *sleep *taskload *EEG *EOG *ECG *Core temperature

  31. Wegmann, Institute of Aerospace Medicine, Germany, 1995: • night flight main cause of stress • second night more stressing and fatiguing than first night: ”flight duty is permissable, but not recommended” • 29% of the pilots could not fly further after first flight • 43% not after the second flight • including layover, sleep loss was accumulated to 9 hours upon return to home base

  32. Wegmann, Institute of Aerospace Medicine, Germany, 1995: • ECG showed increased parasympathetic regulatory trend, most pronounced during return flight (indication for drowsiness) • EEG showed signs of increased sleepiness, most pronounced during return flight • Microsleeps (sleep-periods of more than 8 sec duration) were found in pilots 5 times /hour in average during the last part of the return flight

  33. Wegmann, Institute of Aerospace Medicine, Germany, 1995: Author’s conclusion: This duty roaster is approaching the mental & physiological limits of the crew mainly due to • night duty • sleep deprivation during day time • long duty periods without breaks for recuperation

  34. Circadian Rhythm Problems

  35. Symptoms of Jet Lag • Disturbed sleep • inability to fall asleep or stay asleep • Increased drowsiness • Decreased physical or mental performance • Increased reports of fatigue • More negative moods • Gastrointestinal problems

  36. Factors AffectingCircadian Adaptation • The more time zones crossed the more time it takes to adjust • Individual differences • Ability to adapt decreases with age • East vs West travel

  37. Preventive StrategiesSleep Scheduling and Quantity • At stopover • Try to get the same amount of sleep in a 24 hour period as you normally get at home • Trust your own physiology • If you wake up spontaneously and can’t get back to sleep in 15-30 minutes, get up • If you’re sleepy and circumstances permit, sleep

  38. Preventive StrategiesStrategic Napping • Before duty • A nap can improve alertness • If immediately before a duty period, limit nap to 45 minutes or less • Avoid sleep inertia • Naps can last up to 2 hours • Some sleep is better than none

  39. Preventive StrategiesGood Sleep Habits • Sleep Environment • Dark room • Quiet room • Comfortable temperature • Comfortable sleep surface • Lifestyle • Exercise regularly • Avoid alcohol and caffeine • Eat a balanced diet

  40. Further Considerations • Bright light • Pharmacological agents: (benzodiazepams etc, melatonin, alcohol) • Exercise • Diet

  41. If You Remember Nothing Else.... A pilot should be as alert for duty on the last day as on the first A pilot will – at best – declare himself unfit for duty due to fatigue one day too late A fatigued pilot has nothing to do in cockpit

  42. If You Remember Nothing Else.... “The evolution directed by technological and commercial interests should be controlled and guided by teams of specialists in agreement – in order to protect the man in the machine, still present and vulnerable” Jessen, 1994

  43. END! mk/98

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