Maintenance Human Factors: Does it really matter? Civil Aerospace Medical Institute (CAMI) Flight Deck Human Factors Research Branch

Transcription

1 Maintenance Human Factors: Does it really matter? Civil Aerospace Medical Institute (CAMI) Flight Deck Human Factors Research Branch Katrina Avers, Ph.D. Research Scientist, AAM-510

2 To err is human. 2

3 What is human factors? Human factors encompass all those factors that can influence people and their behaviour. In a work context, human factors are the environmental, organisational and job factors, and individual characteristics which influence human performance at work. 3

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5 Does human factors really effect you in your job? 5

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7 NTSB Accident Report On December 7, 2011, about 1630 Pacific standard time, a Sundance Helicopters, Inc., Eurocopter AS350-B2 helicopter, N37SH, operating as a "Twilight tour" sightseeing trip, crashed in mountainous Sundance terrain about 14 Helicopters, miles east of Las Vegas, Nevada. The pilot and four passengers were killed, and the helicopter was destroyed by impact forces and postimpact fire. The helicopter was registered to and Eurocopter operated by Sundance AS350-B2 as a scheduled air tour flight under the provisions of 14 Code of Federal Helicopter, Regulations (CFR) N37SH Part 135. Visual meteorological conditions The with good pilot visibility and and four dusk light prevailed at the time of the accident, and the flight operated under passengers visual flight were rules. The killed helicopter originated from Las Vegas McCarran International Airport, Las Vegas, Nevada, about 1621 with an intended route of flight to the Hoover Dam area and return to the airport. The helicopter was not equipped, and was not required to be equipped, with any on-board recording devices. The accident occurred when the helicopter unexpectedly climbed about 600 feet, turned about 90 to the left, and then descended about 800 feet, entered a left turn, and descended at a rate of at least 2,500 feet per minute to impact. During examination of the wreckage, the main rotor fore/aft servo, one of the three hydraulic servos that provide inputs to the main rotor, was found with its flight control input rod not connected. The bolt, washer, self-locking nut, and split pin (sometimes referred to as a "cotter pin" or "cotter key") that normally secure the input rod to the main rotor fore/aft servo were not found. The investigation revealed that the hardware was improperly secured during maintenance that had been conducted the day before the accident. The nut became loose (likely because it was degraded)[1] and, without the split pin, the nut separated from the bolt, the bolt disconnected, and the input rod separated from the linkage while the helicopter was in flight, at which point the helicopter became uncontrollable and crashed. 7

8 NTSB Safety Issues Improper reuse of degraded self-locking nuts Maintenance personnel fatigue Need for work cards with delineated steps Lack of human factors training for maintenance personnel 8

9 Both the mechanic and the quality control inspector, who inspected the maintenance work completed the day before the accident, were likely fatigued during the December 6 shift, in part, because they had insufficient time to adjust to working an earlier shift than normal. The mechanic and inspector's performance was degraded by fatigue, which contributed to the improper securing of the fore/aft servo connection hardware, the improper installation of the hydraulic belt, and the inadequate post-maintenance inspection of the accident helicopter, respectively. If the work shifts of the maintenance personnel had been consistent, a major source of their fatigue could have been mitigated. 9

10 Is fatigue a one time occurrence? 10

11 Early Maintenance Fatigue Research Field Study of Aviation Maintenance Technicians (Johnson et al., 2001) Shift* Min Max Mean Day (N=30) 3:24 6:38 5:06 Afternoon (N=19) 2:40 6:31 5:04 Grave (N=12) 4:01 6:09 5:00 Average Sleep = 5:05 *Data from about 20,000 hours of Actigraph 11

12 Estimated Annualized Injury Rates Per Hours of Sleep* Hours of Sleep Injury Rates Less than or more *Adapted from Lerman et al, Annualized injury rate per 100 workers. 12

13 Fatigue can degrade every aspect of human capability. (Rosekind, 2013) 13

14 An Example from Industry I have been a lead mechanic for over 25 years for the airlines. Have I ever worked tired or seen others work tired when they shouldn't have? Yes. Do other mechanics, leads and management know about it? Yes. Have mistakes been made due to fatigue? Yes... When errors are made we catch them and repair them and press on with the job. 14

15 FAA Regs: 4 Days Off Every Month June July S M T W T F S S M T W T F S

16 Hr Min Activity 30 Wake-up, shave/groom & dress 30 Eat/prepare breakfast 30 Commute to work drop kids at school/daycare on the way 16 - Duty Period Double Shift? Hr Sleep 30 Commute home 30 Unwind from work stress; watch TV, read, have a beer 30 Eat alone or with friends/family 30 Family/friends time, pay bills, household chores 30 Prepare for bedtime; brush teeth, shower, etc Total hours of activities 4 0 Number of hours left for sleep 16

17 Discussion What is fatigue? 17

18 What is Fatigue? Fatigue is more than sleepiness and its effects are more than falling asleep Fatigue is a complex state characterized by a lack of alertness and reduced mental and physical performance Fatigue has psychological, physiological, and emotional implications that can impact the safe performance of routine and non-routine work activities 18

19 True or False? False! False! False! False! False! False! I know when I am fatigued. With enough will-power I can push through. All I need is some caffeine to keep me going. People need less sleep as they age. Drinking alcohol before bed helps you sleep. Naps don t really help. 19

20 Primary Contributors to Fatigue Time Asleep Time Awake Circadian Rhythm Disruption 20

21 Time Asleep 21

22 Time Asleep Sleep is a basic physiological need Restorative process for the brain and body We cannot survive without sleep 22

23 The Sleep Process More NREM sleep earlier in your sleep period More REM sleep later in your sleep period Need both types (NREM & REM) of sleep to restore sleep deficit Daytime sleep process is more variable 23

24 Do You Have a Sleep Disorder? Sleep disorders result in sleep loss and disturbed sleep Sleepers are often unaware of how they are affected Common symptoms Difficulty falling or remaining asleep Awaking unrefreshed or with a headache Persistent daytime sleepiness Loud or disruptive snoring Snoring accompanied by pauses in breathing Uncomfortable sensations in arms or legs Involuntary movement or twitching of arms or legs 24

25 Sleep Disorders: Who has them? ~ 50 to 70 million Americans have sleep problems Sleep disorders are considered the #1 cause of workplace accidents 55% of those who reported sleeping problems were involved in 75% of accidents requiring medical treatment 25

26 Sleep Quality and Quantity Most people need about 8 hours per night It s preferable to obtain sleep in a single block, but not necessary Naps can help Frequent disruptions (even if they don t wake you) can negate a full night s sleep When you get adequate sleep, you should be able to sit quietly during the day and remain alert even when feeling bored 26

27 Time Awake 27

28 Time Awake Hours of Wakefulness Blood Alcohol Concentration (%) 17 hrs awake, your performance is comparable to someone with a BAC of.05 (Dawson & Reid, 1997) 24 hrs awake, your performance is comparable to someone with a BAC of.10 (Dawson & Reid, 1997) 28

29 Circadian Rhythm Disruption 29

30 Circadian Rhythm Disruption (Your Internal Body Clock) Circadian rhythm approximates a 24 hour cycle Circadian rhythms control many body functions: Sleeping patterns Digestion Hormone production Body temperature Cardiovascular system The circadian clock is set primarily by daylight Work/rest schedules and social interaction also appear to be influencing factors 30

31 The Circadian Rhythm N PM PM PM M AM AM AM Time of Day N 31

32 Contributors to Fatigue Secondary contributors: Sleep disorders, stress, or illness Work schedules Work environment Workload Lifestyle Personal responsibilities Travel across time zones 32

33 Perfect Storm 33

34 The Aftermath 34

35 Symptoms of Fatigue Physical Symptoms Yawning repeatedly Heavy eyelids or microsleeps Eye-rubbing Nodding off or head drooping Headaches, nausea, or upset stomach Slowed reaction time Lack of energy, weakness, or light headedness Mental Symptoms Difficulty concentrating on tasks Lapses in attention Failure to communicate important information Failure to anticipate events or actions Making mistakes even on well-practiced tasks Forgetfulness Difficulty thinking clearly Poor decision making Emotional Symptoms More quiet or withdrawn than normal Lack of motivation to do the task well Irritable or grumpy with colleagues, family, or friends Low morale Heightened emotional sensitivity 35

36 Fatigue: A Hazard Fatigue can be detrimental in your personal life Fatigue can be detrimental in the workplace 36

37 Fatigue: A Health Hazard Fatigue can have serious implications for your health Digestive issues Heart disease and high blood pressure Depression and anxiety Fatigue is associated with: Greater use of sick leave More doctors visits Greater drug and alcohol use Lower sense of well-being 37

38 Fatigue: A Safety Hazard Fatigue can have serious implications in the workplace Judgment and decision making Short-term memory and recall Communication skills Motivation Risk-taking Reaction times Microsleeps Fatigue is associated with: Unstable performance Increase on the job incidents and accidents 38

39 Two hours of sleep loss below 8 hours = performance error/accidents After two weeks, comparable to continuous wakefulness of 17 hours+ 39

40 Think about it. As an aviation mechanic, what tasks or activities could have serious consequences if not performed correctly? 40

41 What can you do to minimize fatigue risk? 41

42 Utilize available resources Use science-based, practical countermeasures that have been identified. Free resources at mxfatigue.com 42

43 You will experience great benefits! INDIVIDUAL Improved quality of life Increased average sleep times Fewer physical illnesses COMPANY Reduced absenteeism Reduced turnover Reduced morale problems Fewer accidents and injuries 43

44 Summary Fatigue can degrade every aspect of human performance Fatigue can have a significant impact on the safety, efficiency, and reliability of aviation operations Causes are known Solutions are known 44

45 A few thoughts to ponder When we talk about Maintenance Human Factors: Fatigue is only one human factors issue There are many more. Human factors is our greatest opportunity for improvement of operational safety We must think about people and the systems in which they operate 45