MODULE 9

HUMAN
FACTORS
Contenido
GENERAL .................................................................................................................................................. 12
GENERAL .............................................................................................................................................. 12
THE NEED TO TAKE HUMAN FACTORS INTO ACCOUNT ....................................................................... 12
FUTURE PREDICTIONS .......................................................................................................................... 12
INCIDENTS ATTRIBUTABLE TO HUMAN FACTORS/ HUMAN ERROR .................................................... 13
SOME INVESTIGATIONS............................................................................................................................ 13
APRIL 28TH 1988 ALOHA AIRLINES B737 ............................................................................................. 13
10TH JUNE 1990 BAC ONE-ELEVEN 500 SERIES REGISTRATION G-BJRT ............................................... 13
26TH AUGUST 1993 AIRBUS A320........................................................................................................ 14
MURPHY'S LAW .................................................................................................................................... 14
HUMAN PERFORMANCE AND LIMITATIONS ............................................................................................ 15
VISION .................................................................................................................................................. 15
THE RODS AND CONES ......................................................................................................................... 15
BLIND SPOTS......................................................................................................................................... 16
HIGH LIGHT LEVELS .............................................................................................................................. 16
VISUAL DEFECTS ................................................................................................................................... 16
EYE PROTECTION .................................................................................................................................. 17
HEARING............................................................................................................................................... 17
PHYSICAL PROPERTIES OF SOUND ....................................................................................................... 17
THE FREQUENCY................................................................................................................................... 18
TIMBRE ................................................................................................................................................. 18
ANATOMY OF THE EAR ......................................................................................................................... 18
HEARING DAMAGE ............................................................................................................................... 18
CONDUCTIVE DEAFNESS ...................................................................................................................... 18
NOISE INDUCED HEARING LOSS (NIHL) ................................................................................................ 19
PRESBYCUSIS (LOSS THROUGH AGEING) .............................................................................................. 19
BALANCE .............................................................................................................................................. 19
EUSTACHIAN TUBES ............................................................................................................................. 19
MOTION SICKNESS ............................................................................................................................... 19
EFFECTS OF ALCOHOL .......................................................................................................................... 19
PRESSURISATION .................................................................................................................................. 19
INFORMATION PROCESSING .................................................................................................................... 20
INTRODUCTION .................................................................................................................................... 20
CENTRAL DECISION MAKING ................................................................................................................ 20
ACTIONS/FEEDBACK ............................................................................................................................. 20
RESPONSE............................................................................................................................................. 20
LEARNING AND MEMORY ........................................................................................................................ 21
ULTRA SHORT-TERM MEMORY (USTM) ............................................................................................... 21
SHORT TERM OR WORKING MEMORY (STM) ...................................................................................... 21
LONG TERM MEMORY (LTM) ............................................................................................................... 21
MOTOR MEMORY ................................................................................................................................ 21
SHORT TERM MEMORY AID ................................................................................................................. 22
SUMMARY ............................................................................................................................................ 22
ATTENTION AND PERCEPTION ................................................................................................................. 22
EXTERNAL STIMULI/CAUSES OF ATTENTION ........................................................................................ 23
INTERNAL CAUSES OF ATTENTION ....................................................................................................... 23
SELECTIVE ATTENTION ......................................................................................................................... 23
DIVIDED ATTENTION ............................................................................................................................ 23
FACTORS AFFECTING ATTENTION ............................................................................................................ 24
STRESS .................................................................................................................................................. 24
MENTAL WORKLOAD ........................................................................................................................... 24
PERCEPTION ......................................................................................................................................... 24
AMBIGUITY ........................................................................................................................................... 24
SUBLIMINAL PERCEPTION .................................................................................................................... 25
SPEECH PERCEPTION ............................................................................................................................ 25
CLAUSTROPHOBIA .................................................................................................................................... 25
SOCIAL PSYCHOLOGY ............................................................................................................................... 26
CLAUSTROPHOBIA .................................................................................................................................... 26
INDIVIDUAL PERSONALITY ................................................................................................................... 26
PERSONALITY........................................................................................................................................ 26
INTERACTION BETWEEN INDIVIDUALS..................................................................................................... 26
ABILITY.................................................................................................................................................. 27
STATUS ................................................................................................................................................. 27
 ROLE ..................................................................................................................................................... 27
TEAMWORKING ....................................................................................................................................... 27
TEAMWORK (GROUP DECISION MAKING) ........................................................................................... 27
IMPROVING GROUP DECISION MAKING .............................................................................................. 28
MANAGEMENT, SUPERVISION, LEADERSHIP, MOTIVATION & PEER PRESSURE ...................................... 28
THE MANAGEMENT ROLE .................................................................................................................... 28
THE SUPERVISORY ROLE ....................................................................................................................... 29
CHARACTERISTIC OF A GOOD LEADER ................................................................................................. 29
WHAT IS LEADERSHIP ........................................................................................................................... 29
WHAT LEADERSHIP IS NOT SUPPOSED TO BE ...................................................................................... 29
ROLES OF THE TEAM MEMBERS........................................................................................................... 30
MEETING PRINCIPLES ........................................................................................................................... 30
THE INDIVIDUAL ................................................................................................................................... 30
EXPECTATIONS ..................................................................................................................................... 30
SHIFTS................................................................................................................................................... 30
TEAMWORK.......................................................................................................................................... 31
RESPONSIBILITIES INDIVIDUAL & GROUP................................................................................................. 31
RESPONSIBILITIES (COMPANY/EMPLOYER).......................................................................................... 31
THE COMPANY'S RESPONSIBILITY ........................................................................................................ 32
MOTIVATION ............................................................................................................................................ 33
EFFECT ON BEHAVIOUR........................................................................................................................ 33
CULTURE ISSUES ....................................................................................................................................... 34
STEREOTYPING MAIN CHARACTERISTICS ............................................................................................. 34
PREJUDICE ............................................................................................................................................ 34
HISTORICAL CAUSES ............................................................................................................................. 34
CULTURAL CAUSES ............................................................................................................................... 34
SITUATIONAL AND INTERPERSONAL CAUSES ....................................................................................... 35
INDIVIDUAL CAUSES ............................................................................................................................. 35
PEER ISSUES.............................................................................................................................................. 35
FACTORS THAT AFFECT PERFORMANCE .................................................................................................. 36
FITNESS AND HEALTH ........................................................................................................................... 36
PYRAMID OF NEEDS ............................................................................................................................. 36
 PERSONAL HEALTH ............................................................................................................................... 36
EXERCISE............................................................................................................................................... 37
PERSONAL HYGIENE AND CARE............................................................................................................ 37
PERSONAL HABITS ................................................................................................................................ 38
RELAXATION ......................................................................................................................................... 38
SLEEP AND FATIGUE, SHIFTWORK ............................................................................................................ 38
BIOLOGICAL CLOCKS............................................................................................................................. 39
BODY TEMPERATURE ........................................................................................................................... 40
SLEEP CREDIT /DEBIT ............................................................................................................................ 41
SHIFT WORK ......................................................................................................................................... 41
TIME OF DAY AND PERFORMANCE ...................................................................................................... 41
DANGERS OF SLEEP DEPRIVATION ....................................................................................................... 41
SLEEP STAGES ....................................................................................................................................... 42
NAPS ..................................................................................................................................................... 42
FATIGUE ............................................................................................................................................... 43
STRESS – DOMESTIC AND WORK RELATED .............................................................................................. 43
WORK LOADING ................................................................................................................................... 43
COPING WITH STRESS .......................................................................................................................... 44
STRESSORS ........................................................................................................................................... 44
ATTENTION/MOTIVATION/PERFORMANCE ......................................................................................... 45
HUMIDITY ............................................................................................................................................. 46
DOMESTIC STRESS ................................................................................................................................ 46
WORK STRESS ....................................................................................................................................... 46
EFFECTS OF STRESS ON HEALTH ........................................................................................................... 46
SIGNS OF STRESS .................................................................................................................................. 47
ALCOHOL, MEDICATION AND DRUG ABUSE......................................................................................... 47
LANDMARKS OF ALCOHOLISM ............................................................................................................. 47
DRUGS ...................................................................................................................................................... 48
RESPONSIBILITIES ................................................................................................................................. 48
FITNESS................................................................................................................................................. 49
MEDICINES IN COMMON USE .............................................................................................................. 49
TIME PRESSURE AND DEADLINES ......................................................................................................... 50
 MANAGING THE ACTUAL OR SELF-IMPOSED PRESSURE ...................................................................... 50
SHIFT AND TASK HANDOVERS .............................................................................................................. 50
WORKLOADOVERLOAD AND UNDERLOAD .............................................................................................. 50
FACTORS DETERMINING WORKLOAD .................................................................................................. 51
WORK OVERLOAD ................................................................................................................................ 51
WORK UNDERLOAD.............................................................................................................................. 51
WORKLOAD MANAGEMENT ................................................................................................................ 51
WHAT IS WORKLOAD MANAGEMENT? ................................................................................................ 51
WHY IS TEAM WORKLOAD MANAGEMENT IMPORTANT? ................................................................... 51
LACK OF MANPOWER........................................................................................................................... 52
MAINTAINING SAFETY NEEDS .............................................................................................................. 52
HF EXPOSURE CAUSED BY UNPLANNED WORKLOAD .......................................................................... 52
PHYSICAL ENVIRONMENT ........................................................................................................................ 52
HEATING AND LIGHTING ...................................................................................................................... 52
HEATING ............................................................................................................................................... 53
LIGHTING .............................................................................................................................................. 53
NATURAL LIGHTING.............................................................................................................................. 53
EMERGENCY LIGHTING......................................................................................................................... 53
VENTILATION ........................................................................................................................................ 54
PERSONAL CARE ................................................................................................................................... 54
NOISE.................................................................................................................................................... 54
VIBRATION............................................................................................................................................ 55
THE WORKING ENVIRONMENT ................................................................................................................ 55
WORKSPACE ......................................................................................................................................... 55
THE WORKING ENVIRONMENT ............................................................................................................ 55
ANTHROPOMETRY ............................................................................................................................... 56
PHYSIOLOGY ......................................................................................................................................... 56
PSYCHOLOGY ........................................................................................................................................ 56
ENGINEERING ....................................................................................................................................... 56
SUMMARY ............................................................................................................................................ 56
SITUATIONAL AWARENESS (SA) ........................................................................................................... 57
TASKS........................................................................................................................................................ 57
 PHYSICAL WORK ................................................................................................................................... 57
CLOTHING ............................................................................................................................................. 57
BODY POSTURE .................................................................................................................................... 57
BODY MOVEMENTS.............................................................................................................................. 58
DOS AND DON'TS OF LIFTING............................................................................................................... 58
HEIGHT ADJUSTABLE WORK PLATFORMS ............................................................................................ 59
DOCKING SYSTEMS ............................................................................................................................... 59
REPETITIVE TASKS..................................................................................................................................... 59
VISUAL INSPECTION ............................................................................................................................. 60
PARALLAX ERROR ................................................................................................................................. 60
VISUAL AIDS ......................................................................................................................................... 60
COMPLEX SYSTEMS .............................................................................................................................. 60
CRITICAL MAINTENANCE TASKS ........................................................................................................... 60
ERROR-CAPTURING METHODS ............................................................................................................. 61
INDEPENDENT INSPECTION (DUPLICATE INSPECTION) ........................................................................ 61
REINSPECTION PROCEDURE ................................................................................................................. 61
PRECLOSURE INSPECTION PROCEDURE ............................................................................................... 61
MAINTENANCE ON THE DUPLICATED (REDUNDANT) SYSTEMS ........................................................... 61
TECHNICAL DOCUMENTATION: ACCESS, USE AND QUALITY ............................................................... 61
AVIATION TECHNICAL DOCUMENTATION STANDARDS ....................................................................... 63
COMMUNICATION ................................................................................................................................... 63
WRITTEN COMMUNICATION ............................................................................................................... 64
NON-VERBAL COMMUNICATION ......................................................................................................... 64
COMMUNICATION WITHIN & BETWEEN TEAMS ................................................................................. 64
SPOKEN COMMUNICATIONS................................................................................................................ 65
WRITTEN COMMUNICATION FOR THE ENGINEERS ............................................................................. 65
COMMUNICATION PROBLEMS ............................................................................................................. 67
PERCEPTION ......................................................................................................................................... 67
TECHNICAL WORDS .............................................................................................................................. 68
PROCESS DIFFICULTIES ......................................................................................................................... 68
VERBAL REPORTS ................................................................................................................................. 68
WRITTEN REPORTS ............................................................................................................................... 68
 NEWS SUMMARIES .............................................................................................................................. 68
BODY LANGUAGE ................................................................................................................................. 68
NON-VERBAL COMMUNICATION (NVC) ............................................................................................... 69
FUNCTION OF COMMUNICATIONS ...................................................................................................... 70
COMMUNICATION FAILURES ............................................................................................................... 70
WORKLOGGING & RECORDING ................................................................................................................ 71
DOCUMENTATION................................................................................................................................ 71
KEEPING UP TO DATE, CURRENCY............................................................................................................ 72
UPDATING ............................................................................................................................................ 72
DISSEMINATION OF INFORMATION ......................................................................................................... 73
SHIFT HANDOVERS ............................................................................................................................... 73
IMPORTANT CONCEPTS........................................................................................................................ 74
SHIFT HANDOVER EFFECTIVE COMMUNICATION ................................................................................ 74
BARRIERS TO EFFECTIVE COMMUNICATION ........................................................................................ 74
WALKTHROUGH ................................................................................................................................... 75
TASK HANDOVER .................................................................................................................................. 75
ACCIDENT – EXAMPLE .............................................................................................................................. 75
ABSENCE OF COMMUNICATION IN THE HANGAR ............................................................................... 75
WHY DID IT OCCUR? ............................................................................................................................. 75
SO, WHAT CAN BE DONE TO PREVENT A RECURRENCE? ..................................................................... 76
HUMAN ERRORS ...................................................................................................................................... 76
ERROR MODELS AND THEORIES ........................................................................................................... 76
COMPANY CULTURE ............................................................................................................................. 76
ACTIVE ERRORS/FAILURES ................................................................................................................... 77
LATENT FAILURES ................................................................................................................................. 79
RESPONSIBILITIES ................................................................................................................................. 79
HUMAN FACTORS INCIDENT INVESTIGATION .......................................................................................... 79
ICEBERG MODEL ................................................................................................................................... 79
DISCIPLINE ............................................................................................................................................ 80
DISCIPLINE OR NOT .............................................................................................................................. 80
INCIDENT/ ACCIDENT DATA ANALYSIS ................................................................................................. 80
FEEDBACK ............................................................................................................................................. 81
 MODELS DESCRIBING HUMAN FACTORS ............................................................................................. 81
THE 'SHEL' MODEL ................................................................................................................................ 82
REASON'S 'SWISS CHEESE' MODEL ....................................................................................................... 82
THE WEAKEST LINK............................................................................................................................... 83
ACTIVE FAILURE .................................................................................................................................... 83
INADEQUATE SAFETY NETS/DEFENCES ................................................................................................ 84
TOLERANCE/REDUNDANCY .................................................................................................................. 84
CHECKS/DUPLICATE INSPECTIONS ....................................................................................................... 85
FUNCTIONAL TESTS .............................................................................................................................. 85
TYPES OF ERROR IN MAINTENANCE TASKS .............................................................................................. 86
IMPLICATIONS OF ERRORS ................................................................................................................... 87
AVOIDING AND MANAGING ERRORS ....................................................................................................... 88
REGULATIONS ...................................................................................................................................... 88
PROCEDURES ........................................................................................................................................ 88
HUMAN ERROR .................................................................................................................................... 88
ORGANISATIONAL ERRORS .................................................................................................................. 89
LIABILITY ............................................................................................................................................... 89
SAFETY MANAGEMENT ............................................................................................................................ 89
AVOIDING AND MANAGING ERRORS ....................................................................................................... 89
SAFETY CULTURE .................................................................................................................................. 89
JUST CULTURE ...................................................................................................................................... 90
RISK MANAGEMENT ............................................................................................................................. 91
DEVELOPMENT OF THE HAZARD MODEL ............................................................................................. 91
USE OF RISK MATRIX - SEVERITY/LIKELIHOOD MODEL (5X5 RISK MATRIX) ......................................... 93
SAFETY ISSUE RISK ASSESSMENT (SIRA) ............................................................................................... 93
ALARP ................................................................................................................................................... 95
MONITORING OF THE MITIGATION ACTIONS ...................................................................................... 95
TREND MONITORING AND ANALYSES .................................................................................................. 95
INVESTIGATIONS WHERE HUMAN FAILURE OCCURS ........................................................................... 95
PROGNOSIS .......................................................................................................................................... 96
OCCURRENCE REPORTING ....................................................................................................................... 96
MANDATORY REPORTING .................................................................................................................... 96
 VOLUNTARY REPORTING ...................................................................................................................... 96
FEEDBACK TO THE REPORTER .............................................................................................................. 97
ORGANISATIONAL HUMAN-FACTORS PROGRAMME ............................................................................... 97
PROFESSIONALISM AND INTEGRITY ..................................................................................................... 97
ASSERTIVENESS .................................................................................................................................... 97
DISCIPLINARY POLICY ........................................................................................................................... 97
DEALING WITH EMERGENCIES ................................................................................................................. 98
ACTION IN CASE OF EMERGENCY ......................................................................................................... 98
SAFETY ...................................................................................................................................................... 98
HAND TOOLS ........................................................................................................................................ 98
HORSEPLAY........................................................................................................................................... 98
ELECTRICITY .......................................................................................................................................... 99
ACTING IN A CASE OF AN EMERGENCY ................................................................................................ 99
WHAT IS AN EMERGENCY? ................................................................................................................... 99
THE RIGHT SUPPLIES ............................................................................................................................ 99
EMERGENCY CONTACTS AND COMMUNICATIONS .............................................................................. 99
RESPONDING TO AN EMERGENCY ......................................................................................................... 100
POSSIBLE WORK-RELATED EMERGENCIES ............................................................................................. 100
PERSON STOPS BREATHING AND LACKING PULLS ............................................................................. 100
RESCUE BREATHING AND CPR ............................................................................................................ 100
CHEMICAL BURNS .............................................................................................................................. 101
HEAD INJURY ...................................................................................................................................... 101
HYPOTHERMIA ................................................................................................................................... 101
SPINAL INJURY .................................................................................................................................... 101
STRAIN, SPRAINS AND BROKEN BONES.............................................................................................. 102
SPLINTERING ...................................................................................................................................... 102
THE 'DIRTY DOZEN' AND RISK MITIGATION............................................................................................ 102
THE DIRTY DOZEN............................................................................................................................... 102
LACK OF COMMUNICATION ............................................................................................................... 103
SAFETY NETS:...................................................................................................................................... 103
COMPLACENCY ................................................................................................................................... 104
SAFETY NETS:...................................................................................................................................... 105
LACK OF KNOWLEDGE ........................................................................................................................ 106
SAFETY NETS....................................................................................................................................... 106
DISTRACTION...................................................................................................................................... 107
SAFETY NETS:...................................................................................................................................... 107
LACK OF TEAMWORK ......................................................................................................................... 109
SAFETY NETS:...................................................................................................................................... 109
FATIGUE ............................................................................................................................................. 110
SAFETY NETS:...................................................................................................................................... 110
LACK OF RESOURCES .......................................................................................................................... 111
SAFETY NETS:...................................................................................................................................... 112
PRESSURE ........................................................................................................................................... 113
SAFETY NETS:...................................................................................................................................... 113
LACK OF ASSERTIVENESS .................................................................................................................... 115
SAFETY NETS:...................................................................................................................................... 115
STRESS ................................................................................................................................................ 116
SAFETY NETS:...................................................................................................................................... 116
LACK OF AWARENESS ......................................................................................................................... 117
SAFETY NETS:...................................................................................................................................... 118
NORMS ............................................................................................................................................... 119
SAFETY NETS:...................................................................................................................................... 120
SAFETY NETS....................................................................................................................................... 121
RISK MITIGATION METHODS .............................................................................................................. 121
ASSUME AND ACCEPT RISK ................................................................................................................ 121
AVOIDANCE OF RISK ........................................................................................................................... 122
TRANSFERENCE OF RISK ..................................................................................................................... 122
CONTROLLING RISK ............................................................................................................................ 122
GENERAL

GENERAL
'Human Factors' training is essential in the aviation industry because it aims to
reduce the risk of accidents caused by human error. Everyone involved in aviation,
from flight crew to baggage handlers, plays a crucial role in flight safety and has
the potential to make mistakes. By understanding how mistakes are made and how
to avoid them, the number of accidents can be significantly reduced. This involves
learning about human physiology, psychology, effective communication, and types
of human error. Cooperation across all sectors of aviation is necessary to ensure
safe and efficient flight operations, investigate incidents thoroughly, and implement
procedures to prevent future occurrences.

THE NEED TO TAKE HUMAN FACTORS INTO ACCOUNT

Considering human factors is crucial in aviation because human error is always a
risk. While early aviation pioneers took significant risks with little regard for safety,
the advancement of aircraft and air transport services led to the adoption of the
"Flight Safety" philosophy. Improved design has increased reliability, making air
transport very safe compared to other modes. However, human error remains a
major challenge. Current statistics indicate that 80-90% of aviation accidents are
due to human error, with pilot errors being prominent and maintenance-related
accidents increasing annually, raising concerns.

FUTURE PREDICTIONS
While the global major accident rate in commercial aviation is gradually
decreasing, there have been periods, such as from 1983 to 1990, where this wasn't
the case. Despite the low accident rate, the increasing volume of air traffic could
lead to a higher absolute number of accidents. Without further improvements in the
accident rate, this rise in traffic could result in more major accidents annually,
potentially undermining public confidence in the aviation industry.

Fig 01 - HF error rate

Who makes mi stakes?

- Flight crews, Maintenance Crews, Ground crews, ATC, Designs,
Manufacturers, Regulator s
- Everyone can make inadvertent mistakes
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 Fig 02 - Accidents Rate

INCIDENTS ATTRIBUTABLE TO HUMAN FACTORS/ HUMAN ERROR

Maintenance errors are not some new phenomena, but with the advent of more
reliable aircraft, and human factor training for aircrew, the maintenance component
as the cause of an aircraft accident has become more noticeable.

SOME INVESTIGATIONS

APRIL 28TH 1988 ALOHA AIRLINES B737

The Aloha Airlines Boeing 737 accident on April 28, 1988, was a significant case
that highlighted the impact of engineering maintenance and human factors. During
Flight 243 from Hilo to Honolulu, an explosive decompression at 24,000 feet
caused the top of the forward cabin to tear away. One flight attendant was lost, and
seven people were seriously injured, but all passengers survived due to being
belted in. The crew safely landed in Maui. The investigation revealed that the
maintenance program failed to detect severe dis-bonding and fatigue damage in
the fuselage lap joints, and repeated inspections missed obvious corrosion. Poor
maintenance practices, inadequate FAA oversight, and the failure to enforce
Boeing's service bulletins were contributing factors. This incident prompted the
FAA to address human factors in aircraft maintenance.

10TH JUNE 1990 BAC ONE-ELEVEN 500 SERIES REGISTRATION G-BJRT

On June 10, 1990, a BAC One-Eleven experienced explosive decompression at
17,300 feet due to the release of the left-hand windscreen. The captain was
partially sucked out but was held by flight attendants, while the co-pilot regained
control and made an emergency descent, successfully landing in Southampton.

13
The captain sustained injuries but survived. The windscreen had been replaced the
previous night, but incorrect bolts were used: 84 were too narrow and 6 were too
short. This incident marked the first human factors investigation to explore why an
error was made by an experienced person, identifying underlying causes beyond
the individual's mistake.

26TH AUGUST 1993 AIRBUS A320

On August 26, 1993, an Airbus A320 took off from London's Gatwick Airport with
185 passengers and 7 crew. Shortly after takeoff, the co-pilot noticed a severe roll
to the right. Suspecting a sidestick failure, control was handed to the captain, who
confirmed the issue. Unable to turn left or follow ATC instructions, the aircraft was
vectored back to Gatwick. A first landing attempt was aborted due to control issues
when flaps were extended. On the second attempt using a different flap setting, the
aircraft landed safely. Engineers discovered four right-hand spoilers in
Maintenance Mode, isolated from hydraulic systems and moving freely under
aerodynamic loads. This was the first flight after overnight maintenance on the
outboard flap, which required spoiler isolation. Had the aircraft taken off with a
different flap setting, it might not have been controllable.

MURPHY'S LAW
Murphy's Law states that if something can be done incorrectly, it eventually will be.
This principle highlights the inevitability of human error, even among highly
motivated and skilled engineers. While it is unrealistic to eliminate accidents
entirely, they can be significantly reduced by having well-trained personnel, the
right attitude, appropriate equipment, and a strong safety-focused framework. The
example of assembling a bolt with nuts and washers demonstrates that there are
many more incorrect ways to complete a task than correct ones, underscoring the
likelihood of mistakes. Human errors in maintenance, such as incorrect installation
or omission of parts, can cause accidents, sometimes due to errors made years
earlier. Comprehensive record-keeping in aviation helps trace the history of each
component and identify errors, not for punishment but to learn and implement
procedures to prevent future occurrences. This approach is central to Safety
Management Systems (SMS) and Human Factors (HF) considerations.

Fig 03 - Murphy's Law

14
HUMAN PERFORMANCE AND LIMITATIONS

Human performance can be influenced by:

- Physical Condition: Health, and the environments at home and the
workplace.
- Psychological Condition: Mental state influenced by genetics, upbringing,
and mental pressures.

While hereditary factors can't be changed, historical factors like education can be
improved. Factors affecting human performance include:
- The performance of the body's senses.
- The impact of the workplace environment.

Understanding how the body works, especially vision and hearing, is essential for
comprehending how people interact with their surroundings and perform
maintenance tasks.

VISION
Vision is the most crucial sense for humans, heavily influencing emotions and
perceptions. The eye functions like a camera: light enters through the cornea and
lens, with the cornea providing 70-80% of the eye's focusing power. The iris
regulates the amount of light entering the eye by adjusting the size of the pupil,
adapting rapidly to changes in light levels.

Fig 04 - The Eye and Blind Spots

THE RODS AND CONES

The eye's rods and cones are light-sensitive cells in the retina that adapt to varying
light levels. Rods are highly sensitive to low light but only detect black and white,
while cones detect color but require brighter light. Adapting to dark conditions takes

15
about 7 minutes for cones and 30 minutes for rods, allowing vision in very low light.
The lens focuses light onto the retina, where rods and cones convert light into
electrical signals sent to the brain via the optic nerve.
The retina has a blind spot where the optic nerve exits, and visual acuity decreases
as distance from the fovea increases. The fovea provides the sharpest vision, while
peripheral vision detects movement and changes, alerting us to potential danger.
The brain processes the upside-down image projected onto the retina, flipping it to
create a clear, right-side-up perception.

Fig 05 - Approximate distribution of Rods and Cones

BLIND SPOTS
The blind spot on the retina, where the optic nerve enters the eye, lacks light-
detecting cells, causing any image that falls on this area to be undetectable. This is
significant during inspections, such as checking rivets on an aircraft, as it can lead
to missed details if a scanning technique isn't used. For example, when fixating on
a cross while holding a figure close to your face, a filled circle will disappear when
it aligns with the blind spot. Moving the figure closer while keeping your focus on
the cross will cause a cracked rivet to disappear and reappear as it crosses this
blind spot. This demonstrates the need for frequent eye movements to ensure
thorough visual inspections.

HIGH LIGHT LEVELS

Excessive light, such as that found in sunny or snowy environments, can harm the
eyes, particularly through high-energy blue and ultraviolet (UV) wavelengths.
Prolonged exposure can damage the retina. Sunglasses can protect against this
damage if they are impact-resistant, offer appropriate UV filtration, and have a
luminance transmittance of 10-15%. Engineers should also be mindful of UV light
changes during non-destructive testing processes.

VISUAL DEFECTS
Long-sightedness (Hypermetropia) happens when the eyeball is shorter than
normal, causing images to form behind the retina and resulting in blurred vision for
close objects. This condition can be exacerbated by age-related loss of lens
elasticity, known as presbyopia, and is corrected with convex lenses. Conversely,
short-sightedness (Myopia) occurs when the eyeball is larger than normal, causing
16
images to focus in front of the retina, making distant objects appear blurred while
close objects remain clear. Concave lenses are used to correct this condition.

Fig 06 - Eyesight Correction

EYE PROTECTION
When carrying out any task that might involve flying debris i.e. drilling, grinding,
wire cutting or dealing with hazardous chemicals /fluids then protective goggles to
must be worn. When welding, brazing or using ultra violet light the correct shade of
light filter should also be used.

HEARING
The human ear is a specialised receptor organ constructed to respond to sound
waves in the external environment. Additionally, the human ear provides the body
with a sense of orientation and balance.

PHYSICAL PROPERTIES OF SOUND

Sound waves have three major properties AMPLITUDE, FREQUENCY and
TIMBRE (quality). Amplitude of sound waves is responsible for the degree of
loudness. Loudness is expressed in decibels (dB). Mathematically speaking an
increase in sound intensity of 1dB means the loudness has increased by 1.26
times.

Fig 07 - The Physical Properties of Sound

17
 Fig 08 - The Physical Properties of Sound

THE FREQUENCY
The 'Frequency' of a sound wave gives the sound its pitch or tone, and is
measured in cycles per second or hertz (Hz). The human ear is capable of
detecting frequencies between 15Hz and 20,000Hz. Dogs can hear up to 50,000Hz
and bats above 100,000Hz.

TIMBRE
Timbre refers to the unique character or quality of a sound that distinguishes it from
others, even when pitch and intensity are the same. It depends on the sound
source, such as a piano versus a violin, which can produce different sounds
despite having the same amplitude and frequency. This variation arises from the
complexity of the sound waves, as most sounds are composed of complex
mixtures of various waveforms from different vibrating components within the
sound-producing device.

ANATOMY OF THE EAR

The ear converts sound waves into nerve impulses for the brain, but its specialized
receptor cells respond to mechanical stimulation rather than sound waves directly.
The ear's mechanical movements must correspond to sound properties like
amplitude, pitch, and timbre. It is divided into three sections: the External, Middle,
and Inner ear.

HEARING DAMAGE
Hearing difficulties are placed in the following categories: Conductive deafness,
Noise induced deafness and Hearing loss with age (Presbycusis).

CONDUCTIVE DEAFNESS
Damage to the ear's conducting system, including the ossicles or eardrum, impairs
hearing. Perforations or trauma can scar the eardrum or damage middle ear
bones, hindering the transfer of sound vibrations.

18
NOISE INDUCED HEARING LOSS (NIHL)
Exposure to loud noises damages the cochlea's sensitive membrane and its
structures. Initially, hearing loss might be temporary, but continued exposure can
lead to permanent loss, particularly affecting the ability to hear high-pitched
sounds.

PRESBYCUSIS (LOSS THROUGH AGEING)

As people age, their hearing deteriorates, especially for high frequencies. Younger
individuals hear higher pitches better, while older adults lose sensitivity to these
frequencies first. Hearing loss with age is a natural process.

BALANCE
The inner ear, beyond the cochlea, includes the Vestibule and semi-circular canals,
which are essential for balance. The semi-circular canals, filled with fluid and lined
with hair cells, detect rotational and linear movements. The Otoliths, small stones
in the ear, help sense linear acceleration. Together, these components form the
Vestibular apparatus, aiding in spatial orientation and maintaining stable vision
during head movements.

EUSTACHIAN TUBES
The Eustachian Tube connects the middle ear to the nose, helping to equalize air
pressure and prevent damage to the eardrum. Blockage of this tube, such as
during a cold, can cause pressure imbalances, making sounds seem muffled and
affecting ear sensitivity.

MOTION SICKNESS
Motion sickness results from conflicting signals between visual and balance
systems, leading to nausea, sweating, and dizziness. It can be managed by
stabilizing the head, closing the eyes, and minimizing movement. Medication is
available but may have side effects affecting performance, so consult a healthcare
professional.

EFFECTS OF ALCOHOL
Alcohol can affect balance by diluting fluids in the middle ear and otoliths, causing
disorientation and motion sickness that can persist for days after drinking. Even
small amounts of alcohol can impair spatial orientation and balance.

PRESSURISATION
If you are going to be in the flight deck when cabin pressure testing, then you
should be medically cleared. Ear damage, such as a perforated eardrum can be a
result and you should not have a head cold/flu that might block the Eustachian
Tubes/Sinuses.

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INFORMATION PROCESSING

INTRODUCTION
The brain processes information from multiple sources: vision (eyes), sound and
balance (ears), smell (nose), touch (skin, especially fingers), and taste (mouth). It
also monitors internal states such as oxygen levels, CO2, hunger, and bladder
pressure. The brain's structure evolved from early vertebrates, with the cerebellum,
thalamus, and cerebrum each having distinct roles. The cerebellum, part of the
hind-brain, manages automatic functions like breathing and balance, while the
cerebrum, part of the fore-brain, handles higher cognitive processes. Each brain
hemisphere controls functions and receives sensory input from the opposite side of
the body.

Fig 09 - Brain Anatomy

CENTRAL DECISION MAKING

When the brain receives information, it must decide on the appropriate action. For
instance, if a warning light activates during an aircraft engine ground run, an
engineer might need to assess the situation by recalling past experiences and
knowledge. This process involves immediate decision-making and learning, with
relevant information being stored in both short-term and long-term memory.

ACTIONS/FEEDBACK
After deciding on an action, such as turning off a warning light, the brain relies on
feedback to confirm the action's success. This feedback includes auditory signals
(e.g., a click sound), tactile sensations (e.g., the feel of the switch), and visual cues
(e.g., the light turning off). Similarly, driving involves processing multiple inputs—
visual, auditory, and tactile—to adjust steering and maintain control.

RESPONSE
The speed and accuracy of responses to stimuli are interrelated; faster responses
often come at the cost of accuracy. For example, if an engineer falls from a ladder,
a quick but inaccurate reaction might cause injury. Preparedness and expectation

20
can enhance response accuracy. Factors like nutrition, dehydration, visual focus,
distraction, fatigue, age, and alcohol can affect response times.

LEARNING AND MEMORY

Learning is the process of acquiring knowledge or skills through instruction or

experience, which involves storing information in memory. The human brain
manages this by using both short-term memory, for immediate information
retention, and long-term memory, for information stored over long periods.
Information can be transferred from short-term to long-term memory through
consolidation, such as remembering a phone number long enough to dial it or
storing it for future use.

ULTRA SHORT-TERM MEMORY (USTM)

Ultra short term (or sensory storage), has a duration of up to 2 seconds (depending
on the sense) and is used as a buffer, giving us time to attend to sensory input.

SHORT TERM OR WORKING MEMORY (STM)

Short-Term or Working Memory (STM) holds information briefly, around 20 to 30
seconds, unless actively rehearsed. For instance, remembering a phone number or
a page number in a book relies on STM. Without rehearsal, this information is
quickly lost. Acoustic information is generally easier to retain than visual
information due to the ease of repeating sounds compared to memorizing written
data.

LONG TERM MEMORY (LTM)

Long-Term Memory (LTM) is divided into Semantic Memory and Episodic Memory.
Semantic Memory stores general knowledge and meanings, rather than specific
details, and retains information indefinitely, though retrieval can be challenging.
Confusions often involve mixing similar words rather than meanings. Episodic
Memory deals with specific life events and changes over time, with retention rates
declining significantly, leading to potential inconsistencies in recall. For accurate
recall, it's beneficial to document or photograph events immediately. Semantic
Memory generally lasts longer, while Episodic Memory is more precise but less
enduring.

MOTOR MEMORY
Motor Memory involves controlling physical movements such as those of the
hands, feet, and legs. Learning a new skill requires the brain to process information
initially in short-term memory and then transfer it to long-term memory through
rehearsal. For example, learning to drive a car progresses through three stages:
- Cognitive Stage: Understanding and consciously managing each control.
- Associative Stage: Practicing and refining each element, such as clutch use
while gear changing.
- Automatic Stage: Performing the task with minimal conscious thought,
allowing for multitasking, like conversing while driving.

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SHORT TERM MEMORY AID
To improve your chances of remembering information, particularly numbers, it is
sometimes useful to break the number down into more easily handled 'chunks'. For
example, the number 19391914999365 would not be easy to remember when
taken as a whole. However, we can break this number down into more
manageable chunks:

- 1939-Start of World War 2.

- 1914 - Start of World War 1.
- 999 - Emergency phone number in the UK.
- 365 - Days in a year.

By remembering the smaller chunks, we are far more likely to remember the larger
number.

SUMMARY
- There are three parts to memory: Encoding, Storage and Retrieval.
- Most material that is forgotten is lost in the first few hours after learning. If
something is still remembered after a few days, it is unlikely to be forgotten.
- STM has a very small capacity, but the amount in the storage can be
increased by chunking. Material in STM will be lost within 20-30 sees if it is
not rehearsed.
- LTM has a more or less unlimited capacity but the problem is how to retrieve
the information.
- Memory is not like a video - recording; when we remember we reconstruct
the event on the basis of information available in schemata. Material can be
distorted in memory.
- Memory is most efficient where there are lots of recall cues. When there are
few recall cues it may help to be in the same physical or mental state as you
were when you first came across the material.
- What we do before and after learning something may interfere with later
recall. This is especially true if the interfering material is of a similar nature
to the learnt material and is presented just before or just after it.
- Physical shock can disturb memory, especially for events that occurred up
to half an hour before the shock.
- Highly emotionally charged material might be repressed. This does not
make total loss but is in the sub-conscious; it may affect behaviour.
- Acoustic information is easier to remember as the brain finds it easier to
rehearse a sound than a visual image.

ATTENTION AND PERCEPTION

We have seen from previous parts that information is sent to the brain via the
senses - eyes, ears etc. These stimuli are held in the sensory store for a short
time. The information is then sent to the attentional mechanism of the brain.

22
 Fig 10 - Perception

EXTERNAL STIMULI/CAUSES OF ATTENTION

Certain stimuli can capture our attention almost automatically due to their size and
intensity, such as a sudden loud noise in a quiet room. Contrast and change, like a
clock stopping in a silent environment, also grab our focus. Repetition, such as a
student persistently raising their hand or repeated mentions of a product in
advertisements, draws attention. Additionally, moving signs or advertisements are
more noticeable than stationary ones.

INTERNAL CAUSES OF ATTENTION

Certain stimuli can capture attention more effectively, even at low intensity, such as
noticing more cars of the same type or color after buying a similar car, or being
more sensitive to food smells when hungry. However, our ability to process
information is limited by the capacity of working memory and the number of
channels our attention can handle simultaneously. We can focus on stimuli either
selectively or through divided attention, but cannot process all incoming stimuli at
once.

SELECTIVE ATTENTION
Selective attention involves focusing on a specific task while still monitoring other
inputs subtly. This is exemplified by the "cocktail party" effect, where you can
concentrate on a conversation but still notice your name mentioned in a different
group. This ability allows you to switch attention to significant or relevant
information in the unattended channels when necessary.

DIVIDED ATTENTION
If the task in hand is not so complicated as to warrant 'single channel' monitoring,
then the attention can be divided between 2 or more channels. In driving a car, and
talking to a friend, for instance the following channels could be attended.
- The Conversation with a friend.
- The Road Conditions.
- Also Monitoring the Motor Memory operations.

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 Fig 11 - Attention Spans

FACTORS AFFECTING ATTENTION

STRESS
High stress levels typically heighten a person's arousal and focus their attention on
a narrower range of stimuli. This increased sampling rate, while making them more
aware of immediate concerns, can lead to missing important information outside
their limited focus.

MENTAL WORKLOAD
Mental workload is influenced by factors such as stress, task complexity, time
constraints, the operator’s skills, and mental attitude. It reflects the balance
between task demands and the brain’s capacity to handle them. Effective attention
is crucial for processing information, transferring it in and out of working memory,
and facilitating decision-making and motor responses.

PERCEPTION
Perception involves interpreting shapes, colors, and sounds based on memory,
expectations, and sensory input. It’s influenced by optical illusions, depth cues, and
the brain’s tendency to maintain a consistent perception of size and shape despite
changes in retinal images. For example, a person walking away appears to get
smaller due to scaling adjustments made by the brain, and illusions like the Ponzo
illusion and Orbison illusion illustrate how our perception can be manipulated by
contextual cues and depth. Despite changes in the retinal image, objects often
appear constant in size and shape due to these perceptual processes.

AMBIGUITY
Ambiguity in perception arises when the visual information received is either
intentionally misleading or insufficient for clear interpretation, leading to illusions.
For instance, the Necker Cube can be perceived with a small circle either at the
bottom left of one face or in the center of another, with both interpretations being
plausible. Similarly, images like the vase-face illusion can shift between viewing the
image as a vase or two faces, but adding extra features can resolve the ambiguity
and make one interpretation dominant.
Sometimes you see what you want to see or are told to see. Consider the figure:

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 Fig 12 - Letter /Number Illusion

Two groups, one previously shown capital letters and another previously shown
numbers, were both later shown the figure. The letter group chose B and the
number group chose 13.

SUBLIMINAL PERCEPTION
An advertising agency in New York flashed a 3-millisecond message every five
seconds during a film. The audience did not notice the message at a conscious
level but the firm claimed a 56% increase in the amount of Coca-Cola bought in the
intermission. The message was 'Buy Coca-Cola'.

SPEECH PERCEPTION
Speech perception involves distinguishing individual words in continuous speech, a
challenge particularly evident when listening to a foreign language. This process,
known as speech segmentation, relies on recognizing and parsing the different
sounds forming words and sentences. For example, the sentence "She uses
standard oil" is segmented naturally for English speakers, while to non-speakers, it
might sound like a continuous stream of sounds. Additionally, perception involves
organizing, translating, and reconstructing sensory information, using cues like
size, shape, brightness, and color to form a coherent three-dimensional image.
Attention is influenced by external factors such as size, contrast, repetition, and
movement, as well as internal factors including previous experience and emotion.

CLAUSTROPHOBIA

Claustrophobia is an intense fear of enclosed spaces, which can arise

unexpectedly and may not be evident at the start of employment. While mild
discomfort in confined spaces is normal, extreme cases can cause panic,
especially if one is trapped, such as in a fuel tank. If affected, individuals should
inform their co-workers and supervisors so that assistance can be provided in case
of emergencies. Teamwork is crucial to accommodate different body types and
facilitate quick and safe extrication. Those with a known fear of confined spaces
should avoid jobs involving such environments, as panic attacks can cause muscle
rigidity, making escape even more difficult. In severe cases, dramatic measures
like cutting through aircraft skin may be necessary to rescue individuals.

25
 Fig 13 - Claustrophobic environment

SOCIAL PSYCHOLOGY

CLAUSTROPHOBIA

INDIVIDUAL PERSONALITY
Individual personality stems from the unique psychological differences among
people, influenced by genetics, environment, and social interactions. Even identical
twins are distinct in their personalities. Our perceptions of others are shaped by
schemata—mental frameworks based on past experiences and memories—which
can lead to biased impressions. We don’t process all available information about
someone but rely on these pre-existing mental templates to form judgments.

PERSONALITY
Personality encompasses stable behavioral traits that define an individual and
influence their interactions with others. It includes both character, which refers to
moral behavior and strength, and temperament, which describes a person's typical
mood or emotional disposition (e.g., "hot" or "sweet" tempered). While "character"
often relates to moral qualities, "temperament" addresses emotional tendencies.
Together, these aspects help shape an individual's overall personality.

INTERACTION BETWEEN INDIVIDUALS

In a team setting, individuals display various interaction styles that impact team
dynamics and effectiveness. Authoritarian individuals are dominant and intolerant
of dissent but may be submissive to those of higher status. Other styles include
Paternalistic, Interactive, and Submissive, with individuals potentially shifting styles
over time. Effective team members typically balance a goal-directed approach
(focusing on task achievement) with a person-directed approach (caring for team
members). For example, a shift leader should ideally exhibit both high concern for
tasks and team morale (P+ G+). However, in emergencies, an autocratic style (G+)
may be necessary. A team's success and individual contributions depend on
factors like ability, status, and role.

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 Fig 14 - Interactive Styles
ABILITY
An individual's competence significantly affects their effectiveness within a team.
High perceived competence can mitigate deficiencies in personality and interactive
style, making team members more accepting of flaws. A competent autocratic
leader is likely to achieve better results compared to a less capable one, who may
be met with resentment. However, high ability can also have drawbacks: a person
perceived as highly competent might be allowed to pursue an incorrect course of
action unchallenged, as others might assume they know what they're doing.

STATUS
Status in a team can be indicated by hierarchical position or achieved status.
Achieved status is earned through demonstrated professional knowledge,
leadership, and management skills. Subordinates are more likely to follow and
respect a leader who has earned their position through competence and
achievements rather than one who relies solely on their rank.

ROLE
Confusion in a team can arise if multiple leaders give conflicting instructions. To
avoid this, it must be clear who is in charge and the roles of each leader, typically
outlined in 'line management' flowcharts and management engineering documents.

TEAMWORKING

TEAMWORK (GROUP DECISION MAKING)

Group decision-making is generally more effective than individual decisions,
though it may take longer. A group decision rarely surpasses the problem-solving
ability of its most skilled member. While having highly trained personnel on all
shifts would be ideal, practical constraints like cost make this impractical. Several
factors influence group decisions during discussions and debates.

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IMPROVING GROUP DECISION MAKING
Guidelines can be given to improve decision making. Some of these are given
below:
- Avoid arguing for your personal judgements. Approach the task on the basis
of logic.
- Avoid changing your mind only in order to reach agreement or avoid conflict.
Support only solutions with which you are ab le to agree.
- Avoid conflict reducing techniques such as a majority vote or a middle
course strategy.
- View differences of opinion as helpful rather than a hindrance in decision
making.

When these guidelines are used then a group will produce a

better performance than another group not using the guidelines.

MANAGEMENT, SUPERVISION, LEADERSHIP, MOTIVATION & PEER

PRESSURE

Managers and supervisors have a key role to play in ensuring that work is carried
out safely. It is no good instilling the engineers and technicians with 'good safety
practice' concepts, if these are not supported by their supervisors and managers.

THE MANAGEMENT ROLE

Line managers often face the challenge of balancing commercial demands with
ideal safety practices, as directed by top management. For instance, during staff
shortages, they must decide whether maintenance tasks can be safely completed
with fewer personnel or if a worker taking an extended shift can perform
adequately. Adopting Safety Management Principles can aid managers in making
more objective risk assessments.

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THE SUPERVISORY ROLE
Supervision can be formal, as with a designated supervisor, or informal, where
experienced staff guide less experienced colleagues. Supervisors are responsible
for preventing unsafe practices and ensuring adherence to safety norms. They
should be aware of their own potential to adopt the group's culture and periodically
review performance objectively. Balancing supervisory duties with maintaining
personal skills and knowledge can be challenging, especially as supervisors may
face limited oversight due to their seniority, involvement in staff shortages, or
heightened sensitivity to commercial pressures.

CHARACTERISTIC OF A GOOD LEADER

A good leader influences the thoughts and behavior of others through their ideas
and actions. In aircraft maintenance, leaders can be either officially assigned team
leaders or informal figures within the group who command respect, often due to
their dominant personalities. Ideally, the official team leader should also be the one
the team naturally defers to.

WHAT IS LEADERSHIP
Leadership involves motivating the team by clearly communicating achievable
goals and addressing potential problems honestly, while reinforcing good attitudes
and behavior through recognition and constructive criticism. A good leader sets an
example by aligning actions with words, fosters team spirit, resolves disputes, and
maintains cooperation among members. Additionally, the leader must fulfill a
management role by coordinating daily activities, allocating tasks, and resisting the
tendency for team members to shift responsibilities. Effective leadership is
essential for ensuring safety and high performance in aircraft maintenance,
requiring collaboration among managers, supervisors, and technicians to improve
safety culture and airworthiness.

Fig 15 - Leadership

WHAT LEADERSHIP IS NOT SUPPOSED TO BE?

- Leadership is not power. The thug who sticks a gun in your back has power,
but not leadership.
- Leadership is not status. Some may have status or position, yet do not have
a shred of leadership.

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 - Position is assigned from above ... leadership is conferred from below.
- Leadership is not authority. Bosses will naturally have subordinates, but if
bosses do not lead, they will not have followers.
- Leadership is not management. Managing is a planned activity: leadership
is more spontaneous.
- Managers do things right. Leaders do the right things.

ROLES OF THE TEAM MEMBERS

In a team, every member, from cleaners to top management, shares the common
goal of ensuring safe and timely flights for passengers. Each person's role should
be clearly defined, and team leaders should foster teamwork by holding regular
meetings to discuss working conditions, past issues, company and team
performance, future plans, anticipated problems, and any relevant business
updates.

MEETING PRINCIPLES
When leading a meeting, a leader should avoid revealing their own opinions initially
to encourage open discussion from all team members. It’s important to actively
solicit and consider others’ ideas, especially doubts and objections, to ensure all
potential problems are addressed. Once a decision is made, explaining the
reasons behind it helps prevent team members from feeling disregarded, which
encourages future participation and idea-sharing.

THE INDIVIDUAL
Human behavior in the workplace is influenced by a variety of factors, making it
difficult to predict individual responses to events. The impact of an event, like a
lack of soap in the washroom, can vary greatly among individuals, depending on
the frequency of the event and the person's current state of mind. This variability
extends to issues such as harassment, resource shortages, and promotions. To
ensure engineers remain motivated and satisfied at work, it's essential to address
and understand the diverse factors that can influence their motivation and well-
being.

EXPECTATIONS
Expectations for career advancement are crucial for employee motivation,
particularly for those who value promotion and progression. Organizations should
establish clear pathways for career development, though this can be challenging
for smaller firms. Additionally, a competitive salary package, which includes not
only a basic salary but also overtime rates, pension schemes, relocation expenses,
share schemes, private health care, and perks like free flights, plays a significant
role in maintaining worker satisfaction and motivation.

SHIFTS
We can see, from our Circadian rhythms, shift work can affect our sleeping
patterns. This can lead to fatigue, stress and, in the long term, health problems; a
strong de-motivator.
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TEAMWORK
As previously discussed, a close-knit, well managed, motivated team with
supportive management will have a high morale. The team leader should
encourage teamwork and team responsibility.

Fig 16 - Teamwork

RESPONSIBILITIES INDIVIDUAL & GROUP

Leaders should foster loyalty to both the team and the company, promoting a
unified effort towards the company's goals. Aircraft engineers, in particular, must
uphold high safety standards due to their responsibility for passenger safety. When
encountering issues beyond their resolution, engineers should escalate them to
management and consider Mandatory Occurrence Reporting if safety is
compromised. If internal avenues fail to address critical safety concerns, engineers
have a moral obligation to escalate the issue externally, such as through the EASA
Safety reporting system, even if it involves whistleblowing.

RESPONSIBILITIES (COMPANY/EMPLOYER)
Engineers working independently or within a company-approved framework both
bear significant responsibility for aircraft safety. Individual engineers must operate
within their authorizations to ensure safety, while those in company roles are
supported by corporate responsibility, requiring alignment between personal and
corporate standards. The company's manual outlines this relationship. Additionally,
companies are responsible for disseminating safety information to various
stakeholders, including manufacturers, regulatory authorities (CAA & EASA),
engineers, aircrew, and related organizations. Compliance with regulations,
continuous training on Human Factors, and adherence to safe working practices
are essential. Companies should support training and development, ensure
accurate documentation, and uphold safety practices under relevant health and
safety regulations. Encouraging open communication and staff meetings helps
foster a motivated workforce and improve overall safety.

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 Fig 17 - Mandatory HF training

Fig 18 - The 4 SMS Components

THE COMPANY'S RESPONSIBILITY

The Company will meet its requirements by:
- Having Company Procedures accessible to all staff.
- Running short courses and procedures for all new employees and updating
all staff as required on new procedures, legislation.
- Having a QA and control system in place to verify that the laid down
procedures are being carried out.
- Meeting the Health and Safety regulations and the Factories Act by ensuring
adequate heating, light, clean air and noise control.
- Having the correct equipment, hangar space, specialist tools and test
equipment.
- Having adequately trained manpower.
- Reviewing, on a regular basis, pay and conditions of employment.
- Having staff meetings, minuted with action taken to encourage a good
working environment.
- At these meetings or by other information means, highlight any incidents
that have occurred in the Company that are Human Performance related.

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 - Keep a record of incidents that are Human Performance related so that
adverse trends can be noted and acted upon.

MOTIVATION

Motivated behavior is purposeful and goal-directed, crucial in contexts like aircraft

maintenance. While technicians are trained for specific tasks, their actual
performance is heavily influenced by their motivation. Motivation, a fundamental
drive that energizes and directs behavior, can be either positive or negative. It
explains the disparity between capabilities and actual actions. Although motivation
generally propels individuals toward achievement, it doesn't guarantee correct
actions, as seen with highly motivated criminals. Motivation is complex and varies
among individuals; for example, an artist may work tirelessly on an unsellable
painting, while a businessperson might sacrifice family life for financial gain. In
aircraft maintenance, motivation is key for safe and efficient work, but conflicting
factors like financial incentives or harsh conditions can lead to unsafe practices.
Motivation can be classified as:

- External (Extrinsic): Driven by rewards and punishments.

- Internal (Intrinsic): Driven by personal satisfaction and self-determination.

Internal motivation, where actions are driven by personal desire rather than
external rewards, is more effective. Mismanaging rewards or punishments can
undermine intrinsic motivation and negatively impact performance.

Fig 19 - Intrinsic vs. Extrinsic Motivation

EFFECT ON BEHAVIOUR
Rewards and punishments significantly influence workplace behavior, but their
effectiveness varies among individuals. Rewards are most effective when given
immediately after the desired behavior, while delayed punishments can lead to
resentment and are less likely to improve behavior. In cases labeled as having
"doubtful effects," opposing factors make the outcomes uncertain.

33
 Fig 20 - Time in motivation matters
CULTURE ISSUES

Disharmony in the workplace often stems from cultural differences and deep-
rooted ideologies carried from childhood. Conflicts arise when these differences
lead to a loss of control, causing significant disruption. People tend to view those
outside their group as markedly different, leading to stereotyping and developing
strong biases—both positive and negative—towards these "out-group" members.

STEREOTYPING MAIN CHARACTERISTICS

Stereotyping involves three main characteristics:
- People are categorized based on visible traits like race, sex, nationality, or
appearance.
- It assumes that all members of a group share the same characteristics.
- Individuals identified as part of a group are automatically attributed with
these assumed traits.

PREJUDICE
Prejudice involves positive or negative attitudes towards a group. Negative
prejudice can lead to discrimination. The causes of prejudice and discrimination
include historical/economic factors, cultural influences, situational or interpersonal
dynamics, and individual characteristics.

HISTORICAL CAUSES
Historical causes of prejudice include the legacy of colonialism, where groups like
blacks and Asians were exploited and deemed inferior. This historical context has
contributed to ongoing discrimination. Marxist sociologists argue that prejudice
serves to uphold social hierarchies, allowing ruling classes to justify the exploitation
of certain groups.

CULTURAL CAUSES
Cultural causes of prejudice include factors such as increased urbanization, which
can lead to competition for resources and jobs, and mechanization leading to
unemployment. Changes in education, the rise of media influence, shifts in family
structures and morality, and upward social mobility of certain groups also
contribute to heightened prejudice. These social processes can formalize and
reinforce unequal treatment, further entrenching prejudice within society.

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SITUATIONAL AND INTERPERSONAL CAUSES
Situational causes of prejudice often involve conformity to group norms, where
individuals may adopt prejudiced attitudes to fit in with their group. For instance,
people might behave prejudiced if their group holds such views, even if they
personally do not. Historical examples include restaurant owners in the 1960s
Southern USA who cited customer preferences as a reason for refusing service to
Black individuals, even if they themselves were not prejudiced. As social situations
and norms evolve, so too can prejudices.

INDIVIDUAL CAUSES
Prejudice in individuals can be explained by two main theories. The
frustration/aggression hypothesis suggests that when people are blocked from
achieving their goals or have something taken away, they experience frustration
and aggression, which may be redirected onto a "scapegoat." Alternatively, some
individuals develop prejudice due to flaws in their personality, such as a strict
upbringing with prejudiced parents. In the workplace, prejudice can manifest as
harassment, causing stress through various forms like physical contact, language,
or gestures. While achieving a perfect, non-judgmental, and harmonious work
environment might be unrealistic, fostering understanding and prioritizing safety
and professionalism in aircraft maintenance are essential goals.

Fig 21 - Prejudice

PEER ISSUES

In aircraft maintenance, technicians may face peer pressure, which is the actual or
perceived influence to conform to colleagues' expectations. For instance, an
individual might feel pressured to cut corners to meet deadlines, influenced by
peers who may not follow procedures. This pressure stems from the broader
concept of conformity, where one's actions and perceptions align with group
norms. Peer pressure can impact safety positively or negatively, depending on the
organization's culture. A positive safety culture encourages adherence to
procedures, while a negative culture fosters shortcuts and noncompliance.
Experiments on conformity have shown that individuals often align their judgments
with the group's incorrect choices, highlighting how peer influence can affect
behavior.
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FACTORS THAT AFFECT PERFORMANCE

FITNESS AND HEALTH

Human well-being encompasses physical, social, emotional, and intellectual
needs. Physical needs involve essential physiological functions like breathing and
movement. Social needs relate to interactions and a sense of belonging. Emotional
needs include feelings such as joy and anxiety. Intellectual needs focus on mental
activities like learning and problem-solving. Abraham Maslow's Hierarchy of Needs
is a well-known model that organizes these needs into a pyramid, suggesting that
basic needs must be met before higher-level needs can be addressed.

PYRAMID OF NEEDS
Maslow's Pyramid of Needs outlines a hierarchy of human needs, starting with
basic physiological needs such as air, food, and water at the base. Above these
are stimulation needs like sex and exploration, followed by safety needs including
security and protection. Love involves relationships and intimacy, while esteem
focuses on respect and self-worth. Self-actualization is about realizing one's full
potential. Cognitive needs relate to seeking knowledge and understanding, and
aesthetic needs involve a desire for beauty and worship. Individuals must satisfy
lower-level needs before progressing to higher ones. Unmet needs can lead to
physical and mental health issues, impacting workplace performance. Personal
well-being and workplace conditions are interconnected, affecting overall health
and job effectiveness.

Fig 22 - Maslow's Hierarchy of Basic Human Needs

PERSONAL HEALTH
To maintain good physical health, it's essential to follow a balanced diet, get
sufficient sleep, exercise regularly, practice good hygiene, and allow time for

36
relaxation. A diet rich in meat, fish, fruits, vegetables, and plenty of water provides
necessary vitamins and energy. Limiting alcohol intake and avoiding excessive
snacking, especially on sweets, helps prevent imbalances in blood sugar levels.
Disrupted eating patterns, such as those from shift work, can lead to fluctuating
insulin levels and feelings of faintness.

Fig 23 - Health Guide

EXERCISE
Regular exercise doesn't need to be intense; just 20 minutes a day of moderate
activity, like swimming or brisk walking, is beneficial. Exercising first thing in the
morning is often recommended, though it should fit your schedule. If you have any
medical concerns related to exercise, consult your doctor before starting a new
routine.

Fig 24 - Personal Exercise Habits

PERSONAL HYGIENE AND CARE

Maintaining good personal hygiene involves daily showers to prevent body odor,
regular dental care, and consistent bathroom habits. For those working in strong
sunlight, protective measures like hats, sunglasses, and sunblock are essential.
Regular medical and dental check-ups also contribute to overall physical health
and well-being.

37
 Fig 25 - Personal Hygiene Habits

PERSONAL HABITS
Avoid excessive alcohol, it acts as a depressant and it dehydrates the body. Avoid
smoking, it is a carcinogenic practice. The only drugs to be taken by an aircraft
engineer are these prescribed by a doctor, or available over the counter at a
pharmacy and then only taken as instructed.

Fig 26 - Bad habits

RELAXATION
Good for the mind and the body. It is always a good idea to set aside a
daily/weekly period for some form of hobby/sport/ relaxation event this helps
relieve stress and can revitalize the system.

SLEEP AND FATIGUE, SHIFTWORK

Sleep is crucial for overall well-being, with an average need of about 8 hours per
day, though individual requirements may vary. It helps the body recover from daily
activities and supports mental health through processes during sleep. Sleep
involves cycles from drowsiness to REM sleep, and its duration can be influenced
by internal rhythms and external factors like alarm clocks.

38
 Fig 27 - Stages of Sleep

BIOLOGICAL CLOCKS
Circadian rhythms are internal biological cycles with an average period of about 24
hours, influenced by external cues like light, darkness, and social activities (e.g.,
meal times). These cues, known as zeitgebers (German for 'time givers'), help
synchronize our rhythms to the 24-hour day. Without these cues, such as in
isolation, circadian rhythms can extend to about 25 hours. For modern air travelers,
crossing multiple time zones can disrupt their internal clocks, causing a mismatch
between local time and their body's internal time.

Fig 28 - Circadian Rhythms

39
 Fig 29 - Circadian Rhythm body functions

BODY TEMPERATURE
The body's sleep/wake cycle and temperature cycle are closely linked. Body
temperature peaks around 6 PM and hits its lowest point around 5 AM, making it
hard to stay awake at the lowest temperature. We feel drowsy when the
temperature drops and most alert when it rises. This temperature rhythm continues
regardless of sleep patterns and can contribute to jet lag when crossing time
zones.

Fig 30 - Circadian Rhythm of Body Temperature

40
SLEEP CREDIT /DEBIT
The sleep/wake system can be viewed as a credit/debit system where 8 hours of
sleep (credit) supports 16 hours of wakefulness (debit). One hour of sleep typically
provides 2 hours of alertness. However, even after 10-12 hours of sleep following
strenuous activity, only 8 hours of credit is achieved, leading to sleepiness after 16
hours. Sleep cannot be banked for future wakefulness, and lack of sleep results in
cumulative sleep debt.
Sleep is most restorative when taken as body temperature falls, aligning with
circadian rhythms. Naps can help reduce sleep debt. Mismatched sleep/work
patterns, especially during night shifts, can cause desynchronization with circadian
rhythms, making it challenging for some people to adapt.

SHIFT WORK
Management must address the effects of shift work on engineers. Shift rotation
doesn’t necessarily help; instead, shifts are often moved forward (midnight to 8
AM) or backward (5 PM to midnight) after a break. Moving shifts backward aligns
better with the body's natural circadian rhythm. Compressed shift patterns, like
working 4 days of 10-12 hour shifts followed by 3 days off, are another approach.
Shift patterns vary based on the nature of work, such as Base or Line
Maintenance, and whether the work is more physical or mental. Due to these
differences, there is no universally optimal shift pattern.

Fig 31 - Brain and glands' function

TIME OF DAY AND PERFORMANCE

Performance on various tasks varies with the time of day and body temperature. It
improves as temperature rises and declines as it peaks and falls. Short-term
memory tasks decline throughout the day, while verbal reasoning and mental
arithmetic are best around midday. Low body temperature negatively affects
reaction times, vigilance, and manual dexterity. Significant early morning accidents,
such as Chernobyl, Three Mile Island, Challenger, and the BAC 1-11 windscreen
incident, occurred between 3:00 and 5:00 AM. Driving accidents peak around 3:00
PM, possibly due to overconfidence from the circadian rhythm's peak, though other
factors may also contribute.

DANGERS OF SLEEP DEPRIVATION

Sleep deprivation poses physical dangers, significantly slowing reaction times.
Research shows that with just 2 hours of sleep deficit, reaction times are similar to

41
those after consuming one pint of beer. A 4-hour sleep deficit impairs reaction
times to the extent of drinking two pints, making activities like driving hazardous
due to the inability to respond quickly in dangerous situations.

SLEEP STAGES
The various states of sleep have been classified in 5 stages.
- Stage 1 is the transitional phase from waking and sleeping.
- Stage 2 is a more stable sleep.
- Stage 3 and 4 will be light to deep sleep.
- Stage 5 of sleep is called Rapid Eye Movement or REM sleep.

Fig 32 - Sleep Cycle

During sleep, brain nerve cells remain active but perform different tasks than when
awake. Sleep consists of distinctive non-rapid eye movement (NREM) and rapid
eye movement (REM) stages, with REM sleep involving irregular brain activity
similar to wakefulness and characterized by vivid dreams, earning it the name
"Paradoxical sleep." Sleep cycles occur approximately every 90 minutes, with early
stages progressing from light to deep sleep, followed by a short REM phase. Later
cycles have longer REM periods, with about 50% of total sleep being stage 2. Slow
Wave Sleep is crucial for physical restoration, while REM sleep aids in memory
organization. More Slow Wave Sleep follows physical exertion, and REM sleep
increases after learning. Deprivation of either type leads to its rebound in
subsequent sleep periods.

NAPS
Naps can help manage sleep credit/debit, but their effectiveness varies by
individual and the sleep stages experienced. Upon waking from a nap, responses
and reactions are slower for about 5 minutes. Habitual nappers benefit more from
naps, especially when they last at least 10 minutes.

42
FATIGUE
Fatigue, difficult to measure medically, arises from heavy physical or mental
workloads, sleep deprivation, and lack of rest. It is exacerbated by working during
typical sleep periods, long hours, rotating shifts, task complexity, and
environmental factors like heat and humidity. Fatigued individuals are more prone
to errors, increasing the risk of accidents or incidents, such as in aviation.

Fig 33 - Sleep Disorders

STRESS – DOMESTIC AND WORK RELATED

WORK LOADING
In engineering, stress is the force applied to a structure, while strain is the
deformation caused by that force. Similarly, for humans, stress refers to mental
and physical loads, and strain manifests as changes in blood pressure, pulse rate,
weight, and mood. Mental stress is hard to measure and varies among individuals.
Excessive, prolonged stress can lead to health issues, but some stress is natural
and can enhance performance. Too little stimulation can result in boredom,
irritability, and illness. Stress arises from the individual's perception of demands
and their ability to cope, rather than the actual demands or abilities.

Fig 34 - Work load

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 Fig 35 - Stress Raisers

COPING WITH STRESS

Coping with stress involves a feedback mechanism that influences the stress
experienced. Successfully completing a perceived difficult task reduces perceived
demand and increases perceived ability, thereby reducing overall stress.
Conversely, if a task perceived as easy encounters difficulties, the perceived
demand increases and ability decreases, leading to higher stress in future
attempts. Stress responses vary between individuals and can change based on
context, meaning what is stressful for one person at one time might not be stressful
at another.

Fig 36 - Coping With Stress

STRESSORS
Different stressors affect different people to varying extents.
Typical stressors include:
- Physical, such as heat, cold, noise, or the onset of fatigue;

44
 - Psychological, such as worries about rea l or imagined problems (e.g.
financial problems, ill health, etc.);
- Reactive, such as event s occur ring in everyday life (e.g. working under un
realistic time pressure, bullying, encountering unexpected situations, etc.).

ATTENTION/MOTIVATION/PERFORMANCE
Stress can have both positive and negative effects on performance, depending on
arousal levels, as shown by the inverted U curve:
- Low Arousal: Low motivation and dull attention lead to poor performance
due to minimal task demands.
- Optimal Arousal: Efficient performance occurs with enough demands to
maintain attention and handle complex tasks.
- High Arousal: Performance deteriorates with increased errors and narrowed
focus, leading to emotional disturbances.

The autonomic nervous system regulates arousal:

- Sympathetic System: Prepares the body for "fight or flight" by increasing
energy, heart rate, and alertness.
- Parasympathetic System: Restores normal functioning after stress.

Physiological responses to stress include pupil dilation, increased heart rate,

inhibited saliva flow, and heightened adrenaline levels. Stress responses can be
triggered by anticipation alone.
Environmental/Physical Stress Factors:
- Temperature: High temperatures increase heart rate and sweating, while
low temperatures cause discomfort and reduced fine motor control.
- Noise: Moderate noise can enhance performance, but excessive noise
disrupts attention and causes irritability.
- Vibration: Vibration can impair vision, motor performance, and cause
various physical discomforts, contributing to fatigue in activities like
helicopter flight.

45
 Fig 37 - Stress Versus Performance
HUMIDITY
Humans are most comfortable at a relative humidity level of 40-60%. Low humidity
causes discomfort by drying out mucous membranes and eyes, leading to irritation.
High humidity, on the other hand, makes physical exertion uncomfortable and
hinders the body's ability to cool itself through sweating.

DOMESTIC STRESS
Domestic stress includes emotional issues related to relationships, finances,
health, and housing. For example, the loss of a partner is rated as extremely high
stress, which can severely impair performance and reactions. During such times,
individuals should not be expected to perform duties until they are ready to do so
normally.

WORK STRESS
Work stress can arise from excessive workloads, either continuously or in short
bursts, leading to narrowed focus and neglected tasks. The physical work
environment, including factors like temperature and noise, also impacts
performance. Hazards such as dust and chemicals increase stress by raising
awareness levels. Stress may also stem from job monotony, lack of skills, or
management pressures prioritizing short-term gains over safety and good
practices, leading to organizational stress. This can result in staff illness,
absenteeism, poor relations, and a high accident rate. Poor management and
harassment, along with individual physical limitations or overloading oneself, can
further contribute to work-related stress.

EFFECTS OF STRESS ON HEALTH

Stress can lead to long-term health issues, starting with gastrointestinal problems
like indigestion and ulcers. Prolonged stress is linked to elevated blood pressure,

46
which can cause coronary heart disease, heart attacks, and strokes. Additionally,
stressed individuals may experience higher rates of asthma, headaches, sleep
disorders, neuroses, and are more prone to colds and influenza.

SIGNS OF STRESS
Under stress, individuals may display signs such as restlessness, trembling,
nervous laughter, and impulsive behavior. They might take longer with routine
tasks and show changes in smoking or drinking habits. Stress can increase
accident risk, impair memory and concentration, and affect decision-making. Other
signs include anxiety, aggression, mood swings, apathy, fatigue, and low self-
esteem, with aggression manifesting as irritability, threats, and bad temper.

ALCOHOL, MEDICATION AND DRUG ABUSE

Alcohol is quickly absorbed in the stomach and small intestine, with absorption
rates influenced by factors like water and protein content. It is processed by the
liver, where excessive consumption over time can cause liver damage, including
cirrhosis and thiamine deficiency, which can lead to brain neuron loss and
amnesia. Tolerance to alcohol develops with repeated use, affecting the central
nervous system's sensitivity. Dependence on alcohol, or alcoholism, results in
withdrawal symptoms such as anxiety, anorexia, insomnia, and tremors. During
withdrawal, individuals may exhibit hyper-alertness, irritability, jerky movements,
disorientation, and hallucinations, which can cause fear.

LANDMARKS OF ALCOHOLISM
Early significant landmarks of ensuing alcoholism are:
- Constant drinking for relief of tension and anxiety (possibly brought on by
stress)
- Psychological dependence
- Onset of memory blackouts
- Surreptitious drinking
- Urgent need to drink
- Increased tolerance to increasing amounts of alcohol

Chronic Stage
- Inability to stop drinking
- Loss of outside interest
- Work and money troubles
- Neglect of food and Personal Relationship difficulties
- Feelings of guilt, remorse, depression and Loneliness

Treatment for alcohol abuse or addiction should involve support from local health
centers, groups like Alcoholics Anonymous, and support from friends and family.
Ongoing alcohol consumption can lead to severe health issues, including liver
damage, cirrhosis, alcoholic hepatitis, and disorders affecting muscles, bones, the
pancreas, heart, and brain. For aviation engineers, it is crucial to maintain a blood
alcohol level of 0% while on duty.

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DRUGS

Medically prescribed drugs come with warnings about potential side effects. If you
experience drowsiness or difficulty concentrating, avoid driving, working on aircraft,
or performing certifications, and consider switching jobs during the medication
period. Always test new medications before starting work to check for side effects.
Recreational drug use includes substances like solvents, cannabis, heroin,
cocaine, and ecstasy, which can lead to addiction. Common traits among addicts
include emotional immaturity, a desire to escape reality, low frustration tolerance,
and poor coping skills. Drug withdrawal symptoms include sweating, tremors, and
cravings, while continued abuse can cause long-term bodily damage.
For aviation safety, alcohol and drug use are unacceptable. Identified issues may
lead to suspension of licenses or company authorizations, and employers may
conduct drug tests before employment, after serious accidents, or randomly.

RESPONSIBILITIES
The International Civil Aviation Organization (ICAO) has amended Annex 1 of the
Convention on International Civil Aviation to extend standards and recommended
practices to all license holders, addressing concerns about medical fitness and the
use of alcohol and drugs.
EASA mandates that individuals must not work on aircraft or perform certification
tasks if their mental condition makes them unfit. It is the individual's responsibility
to avoid work if they feel unfit. Management must be aware of how the environment
affects staff and ensure employees understand their personal responsibilities.
Monitoring one's own fitness for work is now a legal requirement.

Fig 38 - ICAO Annex 1

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FITNESS
If you're unfit for work due to illness, you should seek medical attention and follow
professional advice. For self-evident conditions, you can self-certify unfitness for
work. Gradual or stress-related conditions might not be immediately noticeable to
the individual but could be observed by family, friends, or colleagues. Management
should be informed of any behavioral changes to provide appropriate support and
counseling.

MEDICINES IN COMMON USE

The following are some types of medicines which may impair work performance.
The list is not exhaustive. If the effects are unknown for any prescribed drug seek
expert medical advice before their use.

Fig 39 - Drug Dependency

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TIME PRESSURE AND DEADLINES
Time pressure can be categorized into actual pressure, imposed directly or
indirectly to complete a task within a set timeframe, and self-imposed pressure,
where individuals or teams set unrealistic deadlines for themselves. Both types of
pressure impact performance, and inappropriate pressure—whether self-imposed
or external—can pose safety risks and lead to errors or maintenance shortcuts.

MANAGING THE ACTUAL OR SELF-IMPOSED PRESSURE

To effectively manage both actual and self-imposed pressure, it is essential to
allocate sufficient time for maintenance tasks and conduct comprehensive pre-task
briefings to set clear priorities. Open, two-way communication is crucial for
identifying and mitigating the effects of pressure on performance and behavior. If
faced with tasks outside your expertise or capabilities, seek help and communicate
any unusual or unexpected results. Avoid taking shortcuts or deviating from
procedures due to time constraints, and focus on completing only those parts of
the job that can be done safely and professionally.

SHIFT AND TASK HANDOVERS

Shift and task handovers often present a busy period where paperwork and
briefings are completed in a rush. To ensure a smooth transition, it is ideal to have
an overlap between shifts for a face-to-face handover. When this is not possible,
provide a thorough written handover to the incoming team or individual.
Organizations should implement a formal process for handing over tasks and shifts
to ensure clear communication. Proper planning and communication are key to
managing stress and time pressure during these transitions, with adequate time set
aside for completing outstanding tasks and documentation before the end of a
shift.

WORKLOADOVERLOAD AND UNDERLOAD

Fig 40 - Level of arousal vs performance

Deadlines in line and base maintenance can create significant time pressure,
especially in AOG (Aircraft on Ground) situations, which can compromise safety if

50
engineers prioritize meeting deadlines over safe operation. Achieving optimum
performance requires appropriate levels of arousal and alertness; too much or too
little arousal negatively impacts effectiveness. It’s crucial to recognize stress
symptoms in oneself and others and to understand its effects on team
performance. Performance is closely tied to arousal levels, with both very low
(boredom) and very high (stress, anxiety) arousal leading to degraded
performance.

FACTORS DETERMINING WORKLOAD

Workload in maintenance tasks depends on both controllable and uncontrollable
factors. It is influenced by the nature of the task (physical and mental demands),
circumstances (performance standards, available time, and environmental factors),
and the individual’s abilities (skills, experience, health, and emotional state). Since
workload is subjective and varies from person to person, it should be managed to
fit within an individual’s mental and physical capacities.

WORK OVERLOAD
Work overload happens when the workload exceeds an individual’s or team’s
capacity to manage it. This leads to performance degradation, increased error
rates, and fatigue. Over time, tasks that were initially easy become harder, and
sudden spikes in workload heighten the risk of errors. Proper planning and task
allocation can mitigate the risks associated with work overload.

WORK UNDERLOAD
Work underload, though rare, occurs when tasks are too simple, repetitive, or there
is a lack of tasks. This can lead to boredom and decreased attention, resulting in
increased errors and omissions. Effective management is needed to ensure that
work is neither overly simplistic nor insufficient.

WORKLOAD MANAGEMENT
Workload management involves planning and assigning tasks efficiently among
team members to balance the load. It considers skills, availability, capacity, and
other factors. Proper workload management ensures that tasks are completed
efficiently and within deadlines, while preventing overwork and burnout.

WHAT IS WORKLOAD MANAGEMENT?

Workload management is the process of planning, scheduling, and assigning tasks
to ensure work is completed effectively. It uses planning tools and requires
balancing resources, ensuring proper resource allocation, and avoiding over or
under-utilization of team members. Good workload management leads to improved
production, efficiency, and employee satisfaction.

WHY IS TEAM WORKLOAD MANAGEMENT IMPORTANT?

Effective team workload management helps prioritize tasks, balance work
distribution, and create accurate project schedules. It addresses questions about

51
team workload, resource needs, and burnout prevention. Proper management
improves project outcomes, employee retention, and job satisfaction.

LACK OF MANPOWER
Manpower must be proportional to project needs. Insufficient manpower leads to
delays, safety risks, and increased stress among employees. Adequate manpower
ensures timely and safe task completion, reducing fatigue and improving overall
conditions for workers.

MAINTAINING SAFETY NEEDS

A sufficient workforce reduces the need for overtime, thereby decreasing stress
and improving alertness. Proper manpower alignment with needs ensures workers
are rested and prepared for sudden workload increases. Effective manpower
planning for scheduled and unscheduled maintenance tasks is crucial for safety
and efficiency.

Fig 41 - Manpower demand

HF EXPOSURE CAUSED BY UNPLANNED WORKLOAD

Unplanned tasks, such as those arising from Service Bulletins or Airworthiness
Directives, can disrupt workflow. While such tasks are challenging to plan for,
approximating manpower needs and having robust processes and procedures in
place can help manage this exposure. Ensuring competent and trained employees
is vital for handling unplanned workload effectively.

PHYSICAL ENVIRONMENT

HEATING AND LIGHTING

Human performance in the workplace is influenced by the physical environment,
including factors such as heat, light, ventilation, noise, space, and vibration.
Facilities should provide adequate areas for changing, washing, resting, eating,
and using toilets, which should be clean and tidy. Employers must comply with
Workplace Regulations to ensure a safe and suitable physical environment.

52
HEATING
For indoor work, temperatures should be between 16°C and 21°C for non-physical
work and at least 13°C for manual work. In warmer climates, air conditioning and
humidity control may be necessary. Relative humidity should be between 20% and
85%. Proper heating or cooling, including fans for ventilation, should be provided to
maintain a comfortable working environment.

Fig 42- Heat index

LIGHTING
Workplaces must have sufficient lighting, preferably natural light, to prevent
eyestrain and ensure safety. Lighting should be evenly distributed without glare
and include task-specific lighting for detailed work. Light intensity is measured in
lux, and lighting should be positioned to avoid glare and ensure safety. Proper
lighting prevents misinterpretation of colors and reduces hazards like stroboscopic
effects from rotating machinery.

NATURAL LIGHTING
People generally prefer to work in natural light rather than artificial
light, therefore maximum advantage should be made of the available natural light.
Windows and skylights should be cleaned regularly and kept free of unnecessary
obstructions in order to admit maximum daylight.

EMERGENCY LIGHTING
Emergency lighting is essential for safety during power failures, particularly for
preventing falls and ensuring safe operation of machinery. It should have an
independent power source and automatically activate when normal lighting fails to
ensure continued safety and visibility.

53
VENTILATION
Good ventilation is crucial, especially in enclosed spaces, with a minimum fresh air
supply rate of 5 to 8 liters per second per occupant. Ventilation systems should be
clean and free of contaminants. Special precautions are needed for operations like
paint removal, grit blasting, and chemical processes to manage potential hazards.

PERSONAL CARE
In enclosed spaces with internal combustion engines, there is a risk of carbon
monoxide (CO) poisoning, a colorless and odorless gas that can cause nausea,
headaches, and even death. Proper ventilation and monitoring are essential to
prevent CO buildup and ensure safety.

Fig 43 - Carbon Monoxide Poisoning

NOISE
Noise from equipment like jet engines and pneumatic tools is a significant issue.
Areas where conversation is difficult at 2 meters should be assessed for noise
hazards. Employees in areas exceeding 80dB must be offered hearing protection,
and areas exceeding 90dB should be marked as 'Ear Protection Zones' with
appropriate safeguards in place.

54
 Fig 44 - Noise Chart
VIBRATION
Vibration, particularly from hand-held tools, can lead to Hand Arm Vibration
Syndrome (HAVS) and lower back pain from whole-body vibration. To reduce
these issues, limit exposure time, use equipment designed to minimize vibration,
and incorporate damping materials.

THE WORKING ENVIRONMENT

WORKSPACE
Workrooms must provide ample free space to allow easy movement to and from
workstations. The number of people in a room depends on its size and the space
occupied by furniture, fittings, and equipment. The minimum recommended
workspace is 11 cubic meters per person, which may need to be adjusted based
on room layout and furnishings.

THE WORKING ENVIRONMENT

Ergonomics focuses on optimizing the interaction between workers and their
environment to ensure a good fit between people and their tasks. It aims to adjust
tasks to suit individuals rather than forcing individuals to adapt to tasks.
Ergonomics involves work study and measurement to address poorly designed
equipment and unsafe practices. Key skills in ergonomics include knowledge in
anthropometry, physiology, psychology, and engineering.

55
 Fig 45 - Fitting the task to the man

ANTHROPOMETRY
This is a study of human measurements such as shape, size and range of joint
movements. The machine will be designed to suit a wide range of sizes of man,
using statistical analysis.

PHYSIOLOGY
This is a study of the calorific requirements of work, body functions, the reception
of stimuli processing and response. The Man and Machine must be
complementary.

PSYCHOLOGY
As previously discussed in these notes, but will include 'Distraction' and 'Fatigue '.

ENGINEERING
Engineering involves designing tools and machines to ensure they are user-friendly
and effective. Standardization is crucial to make operations more intuitive and
reduce errors. For instance, the identical flight deck layouts of the Boeing 757 and
767 simplify transitions for engineers and pilots, illustrating how thoughtful design
can minimize operational errors.

SUMMARY
So, when we set up a hangar aircraft maintenance facility or a workshop, we have
to consider the physical effects, the ergonomics and the psycho logical effects on
the people employed. The effects of heat, noise etc. are, over a space of time,
going to cause fatigue in the individual, so reducing his performance and, in the
long term, affecting his physical health. The ergonomics of the workplace, i.e. the
efficient layout of the aircraft, equipment and facilities in the hangar, will also affect
the engineer 's performance by reducing fatigue.
Distraction in the workplace by noise, movement of personnel within the immediate
work area, and telephones ringing can be alleviated by careful screening,
soundproofing and regulated access to work areas. This will minimise maintenance
errors due to unwarranted distractions.

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SITUATIONAL AWARENESS (SA)
Situational awareness (SA) is the ability to understand and interpret the current
state of a system or environment. In aircraft maintenance, this involves knowing
the condition of the aircraft system and any potential impacts of actions taken, such
as operating a hydraulic pump. SA is critical for performance and error prevention.
Challenges in Maintenance:
- Complexity of Systems: Aircraft systems are complex, making it challenging
to assess their state accurately.
- Troubleshooting: Engineers must integrate observed cues to understand
malfunctions and predict future system statuses.
- Team Dynamics: Effective SA requires that all team members have the
necessary information for their responsibilities. This involves both individual
SA and "shared SA," where team members have a common understanding
of the situation.

Team SA Issues: Communication Failures: Errors may occur at various levels:

- Level 1: Information not transmitted successfully.
- Level 2: Information not comprehended the same way.
- Level 3: Implications of information not understood consistently.

Training: Teams should receive training to improve their SA, enabling them to
perform maintenance tasks more effectively and reducing the likelihood of errors
due to miscommunication or incomplete information.

TASKS

PHYSICAL WORK
Aircraft engineers perform tasks that require physical effort, from visual inspections
to complex tasks such as engine installation and testing. These tasks may require
various body positions and the use of the senses with appropriate body
movements.

CLOTHING
Before starting work, engineers should wear properly fitting, comfortable overalls
with secured pockets to avoid foreign object debris (FOD) hazards. The type of
clothing should be appropriate for the temperature and nature of the task.
Footwear should be non-slip, resistant to fuels and oils, and ideally have a safety
toe cap.

BODY POSTURE
The height of workbenches or vices should be aligned with the user's elbow height.
For machinery work, the workpiece should be 5 cm lower than elbow height, and
for visual inspections, it should be between elbow height and 25 cm above. Floors
should be firm and level; using anti-slip platforms is recommended for prolonged

57
standing. When working outside or at height, be cautious of slippery surfaces and
ensure proper safety measures like harnesses and guardrails.

BODY MOVEMENTS
To avoid strain, always seek help or use lifting equipment for heavy or bulky items.
When lifting from the floor, bend the knees, keep the back straight, and use leg
muscles. When carrying heavy items, keep them close to the body and minimize
the time they are held to avoid back strain.

Fig 46 - Lifting Correctly

DOS AND DON'TS OF LIFTING

Avoid twisting the body while lifting or applying force to prevent back problems.
Never pull or push heavy objects that could move unexpectedly; ensure wheeled
vehicles have serviceable brakes. Do not over-reach, especially at height, as this
can lead to imbalance and injury. Use appropriate equipment for working at heights
and follow local regulations.

58
 Fig 47 - Lifting Do's and Don'ts

HEIGHT ADJUSTABLE WORK PLATFORMS

When using height-adjustable platforms, ensure feet are steady before raising,
avoid overloading, and distribute the load evenly. Always have guardrails in place,
keep the gap between the structure and platform narrow, and use safety locks
when raised.

DOCKING SYSTEMS
Docking systems are extensive and designed for specific aircraft types. Guardrails
should be waist-height with low-level screens to prevent small objects from falling.
When working at heights of 3 meters or more, use approved safety harnesses and
secure ladders to strong points on the aircraft.
Working in confined spaces like aircraft fuel tanks requires adherence to specific
safety procedures. Individuals with claustrophobia should avoid these tasks.

REPETITIVE TASKS

Repetitive tasks are those performed frequently or over extended periods, such as
fitting the same rivets daily or conducting numerous inspections on an aircraft.
These tasks can lead to boredom, decreased motivation, and increased errors as
individuals rely on motor memory rather than active thought, fostering complacency
and overconfidence. To mitigate these effects, it’s important to inform management
if a task becomes overly repetitive, take regular short breaks, vary tasks and
positions, and periodically review procedures. Proper planning and task rotation
can also help reduce the impact of repetitive work by introducing variety and
maintaining engagement.

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VISUAL INSPECTION
Visual Inspection involves using our eyes, aided by visual tools and test
equipment, to assess the serviceability of aircraft and their components. Vision is
the primary sense used, though feel, smell, and hearing also contribute. Engineers
must be aware of their visual limitations, such as the need for corrective lenses and
the potential for color perception issues. The inspection environment should have
adequate lighting and minimal distractions to avoid errors. Tools like magnifying
glasses, mirrors, and video cameras can help address visual limitations.

PARALLAX ERROR
To avoid parallax error when reading instruments and gauges, ensure the scale is
parallel to the observer's line of sight. Using a light at a 90° angle to the scale or
instruments with mirrors can help minimize this error.

Fig 48 - Parallax Error

VISUAL AIDS
To address limitations such as blind spots and the eye’s physical constraints, use
tools like magnifying glasses, mirrors, borescopes, fiber optics, video cameras, and
color monitors to improve inspection accuracy.

COMPLEX SYSTEMS
Modern aircraft have integrated mechanical and electronic systems requiring
expertise in both fields. Engineers must understand their specific responsibilities
and be aware of the broader system implications. Documentation should detail
complex tasks in stages, with continuous records for shift changes and handovers.

CRITICAL MAINTENANCE TASKS

These are tasks where errors could jeopardize flight safety. They include work on
flight controls, propulsion systems, and fuel systems, among others. Identifying
critical tasks involves analyzing design data, incident reports, and other sources.
Tasks should be scheduled when personnel are most alert, and maintenance

60
documentation must highlight critical tasks and include methods for capturing
errors.

ERROR-CAPTURING METHODS
Error capturing method are those actions defined by the organization to detect
maintenance errors made while performing maintenance. The examples are
independent inspections, reinspections, pre-closure inspections and maintenance
on the duplicated (redundant) systems.

INDEPENDENT INSPECTION (DUPLICATE INSPECTION)

This method is used to capture errors on critical tasks by involving two signatories
from different CA holders. The maintenance task is first signed off by the CA holder
responsible for the work, confirming its completion. A second CA holder performs
an independent inspection, reviewing the task, shift handover records, and
maintenance documentation to ensure all work meets required standards. The
independent inspector checks the entire system's integrity, including installation,
rigging, movement, and functionality. A Certificate of Release to Service (CRS) is
issued only after the independent inspection is satisfactorily completed. This
process must be pre-planned and marked in maintenance documents.

REINSPECTION PROCEDURE
Reinspection is used as an error-capturing method when only one CA holder is
available. In such cases, the same CA holder performs both the maintenance task
and the reinspection. Reinspection must be conducted after a minimum break of
half an hour away from the work environment. The CA holder signs both the
maintenance release and the independent inspection area on the task card. The
reinspection involves a thorough review of the task and all related documentation,
ensuring correct installation, rigging, movement, locking, and functionality.

PRECLOSURE INSPECTION PROCEDURE

A preclosure inspection is conducted before sealing off an area of the aircraft to
identify any overlooked issues such as tools, rags, disconnected connectors, loose
clamps, or other potential problems. This inspection must be performed by
someone who was not deeply involved in the work in that area to ensure an
unbiased review.

MAINTENANCE ON THE DUPLICATED (REDUNDANT) SYSTEMS

To prevent repeating mistakes, maintenance on redundant systems (like flight
controls on both wings or oil filters on both engines) should be done by separate
engineers. This approach helps avoid errors that might be replicated on multiple
systems by the same person. Maintenance documents should ensure that the work
on redundant systems is split among different individuals to maintain accuracy and
safety.

TECHNICAL DOCUMENTATION: ACCESS, USE AND QUALITY

Technical documentation is vital in aircraft maintenance and must always be
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accessible, well-maintained, and up-to-date. Key documents, including AMM
(Aircraft Maintenance Manual), IPC (Illustrated Parts Catalogue), SRM (Structural
Repair Manual), CMM (Component Maintenance Manual), WDM (Wiring Diagram
Manual), NDTM (Non-Destructive Testing Manual), as well as MPD (Maintenance
Planning Document), MEL (Minimum Equipment List), CDL (Configuration
Deviation List), ADs (Airworthiness Directives), and SBs (Service Bulletins), are
crucial for maintaining the airworthiness of an aircraft. Without these documents,
no maintenance work should be conducted.
The quality and availability of technical documentation are essential to prevent
accidents and ensure safety. Poor documentation or its absence has historically
contributed to fatal aviation incidents. Technical documentation plays a critical role
in:

- Safety: Ensures maintenance procedures are performed correctly,

preventing accidents and ensuring safety protocols are followed.
- Compliance: Demonstrates adherence to regulatory requirements, showing
that all standards and regulations are met.
- Efficiency: Provides clear instructions and procedures, reducing errors,
saving time, and ensuring consistent process execution.
- Maintenance and Repair: Essential for effective maintenance and repair,
helping to avoid equipment downtime and reduce costs by ensuring proper
servicing.
- Training: Aids in training maintenance personnel by providing detailed
knowledge and procedures, enhancing their skills and effectiveness in their
roles.

Overall, maintaining up-to-date and accessible technical documentation is

fundamental to the safe and efficient operation of aircraft.

Fig 49 - Service Bulletin

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AVIATION TECHNICAL DOCUMENTATION STANDARDS
Several standards guide aviation technical documentation to ensure consistency,
clarity, and efficiency:
- ATA I Spec 2200: A global standard for structuring and delivering aircraft
maintenance manuals (AMMs), illustrated parts catalogues (IPCs), and
component maintenance manuals (CMMs). It ensures technical
documentation is developed and delivered in a consistent and efficient
manner.
- S1000D: An international specification for technical documentation used in
aerospace and defense. It defines a common database and XML data
model for creating, managing, and delivering technical information,
facilitating reuse across various platforms and systems.
- ASD-STE100 Simplified Technical English: A controlled language standard
designed to make technical documentation clear and understandable,
especially for non-native English speakers. It aims to enhance safety and
efficiency by minimizing misinterpretations.

Technical writing for maintenance documentation is formal, objective, and tailored

to meet the needs of trained personnel. It is essential that technical documentation
is strictly controlled to avoid misinterpretations. Maintenance engineers must use
only the most current versions of documentation; as outdated versions are not
acceptable. Organizations must manage publication systems to ensure only up-to-
date manuals are available, and printing should be minimized due to the potential
obsolescence of printed materials.

COMMUNICATION

Effective communication in maintenance requires clarity, credibility, and relevance

from the sender, along with readiness and trust from the receiver. It involves not
just oral exchanges, but also written documentation, nonverbal cues, and physical
signals. Maintenance relies heavily on accurate documentation like logbooks and
manuals, as well as clear, confirmed verbal instructions. Despite being the most
natural form of communication, oral exchanges can be prone to
misunderstandings, as evidenced by past incidents where miscommunication led
to serious consequences. Therefore, in maintenance settings, it’s crucial that all
forms of communication—spoken, written, and physical—are clear, verified, and
properly understood to ensure safety and effectiveness.

Fig 50 - Way of communication

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WRITTEN COMMUNICATION
In aviation maintenance, written communication is crucial due to the significant
amount of paperwork involved. Engineers often spend 25% to 40% of their time
managing documentation. Unlike verbal communication, written documents lack
immediate clarification opportunities, making precision essential. Ambiguities in
language, like the multiple meanings of words, can lead to misunderstandings. To
address this, simplified English is used in aviation manuals to ensure clarity and
reduce misinterpretation.

Fig 51 - Written shift handover is essential part of the communication

NON-VERBAL COMMUNICATION
Non-verbal communication, including gestures, facial expressions, and physical
cues, plays a vital role in maintenance, especially in noisy environments or when
verbal communication isn't possible. Misinterpretations can occur, particularly
under stress. For instance, ambiguous physical cues or incomplete documentation
can lead to operational errors, highlighting the importance of clear, visual, and
physical indicators in maintenance settings.

COMMUNICATION WITHIN & BETWEEN TEAMS

Effective communication networks are essential in organizations, with information
flowing downward from management and upward from employees. Downward
communication involves directives and instructions, while upward communication
often provides feedback and suggestions for improvement. Horizontal
communication between colleagues and departments is also vital for coordinating
tasks. Good communication relies on feedback to ensure messages are
understood and acted upon correctly, helping to foster cooperation and efficiency.

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 Fig 52 - Vertical Communications within a Department

Fig 53 - Internal Communications - Horizontal

SPOKEN COMMUNICATIONS
Between members of a team or organization, spoken communication can be
applied in different ways; For Example:
- One to One Directive - 'Do it this way'
- One to One Discussion - Appraisals and Interviews
- One To Group – Lecture
- Group Discussions - Project Teams, Task Group

WRITTEN COMMUNICATION FOR THE ENGINEERS

Written communications for the aircraft engineer may take many forms i.e.
- Maintenance Manuals.
- Company Engineer Expositions.

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 - Service Bulletins.
- Company Memos etc.

He, in turn, produces written records of:

- Aircraft Maintenance.
- Hand over Reports at shift change.
- Mandatory Occurrence Reports.

From the list we can see the importance of both - written and verbal
communications being used in the directions discussed. The list is not exhaustive
and you may be able to add others you have seen or know about.

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COMMUNICATION PROBLEMS
Distortions and misunderstandings are prevalent in vertical communications,
particularly when messages shift between oral and written forms. Departments,
especially in larger organizations, may work in isolation, leading to strained
communication. Barriers such as perceptions, jargon, technical terms, and process
difficulties must be addressed for successful communication.

PERCEPTION
Miscommunication can occur if the sender misjudges the receiver's understanding
or if the receiver has a biased perception of the sender. Additionally, the use of
different jargon and acronyms between groups can lead to misunderstandings.
Effective communication requires overcoming these perceptual and linguistic
barriers.

Fig 54 - Different perspective

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TECHNICAL WORDS
The transmitter of the message must know his audience. If technical words are
used to communicate to a non-technical person /group, the sense of the message
will become difficult and may be lost.

PROCESS DIFFICULTIES
If there is a difficult message to be communicated and there is no 'feedback' a
problem may exist as a result of the message not being correctly transmitted or
understood.

VERBAL REPORTS
Verbal communication is effective for straightforward messages and when direct
interaction is needed. For simple information, a brief personal discussion or group
briefing can suffice. However, verbal messages can distort as they are passed
along, potentially leading to errors. This issue is exemplified by the famous
miscommunication in the army message that changed significantly by the time it
reached headquarters. Verbal communication can fail due to distractions or lack of
attention. For complex or critical messages, written reports are preferred, as they
provide a record and can be referred back to, ensuring clarity and accuracy.

WRITTEN REPORTS
Written reports must be clear and concise, tailored to the intended reader. They
are often used for commercial policy and company control. Miswriting in reports
can lead to critical errors, as illustrated by the example where a misplaced comma
changed the meaning of a message from "Spare him, not kill" to "Spare him not,
kill," demonstrating the potential for serious consequences due to poor
punctuation.

NEWS SUMMARIES
This is used within organisations to inform employees of changes in company
performance, safety issues, training course information etc. It can be in the form of
a Newsletter, Magazine or a Notice on the bulletin board.

BODY LANGUAGE
Body language includes eye contact, facial expressions, posture, hand and head
movements, and physical proximity, all of which communicate non-verbally and
influence interpersonal relationships. Eye contact should be brief to avoid seeming
threatening. Facial expressions can reveal emotions such as sadness or boredom,
while posture and body movement indicate interest or disinterest. In Western
culture, excessive touch is often unwelcome, and personal space is closely
guarded. Changes in speech patterns, pitch, and voice can convey different
emotions and urgency, with interruptions typically seen as rude and domineering.

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 Fig 55 - What you show but don't say

NON-VERBAL COMMUNICATION (NVC)

Non-verbal communication involves conveying messages through posture, facial
expressions, gestures, and other body signals. These cues can sometimes be
ambiguous and need to be interpreted within the context of the situation. For
instance, a facial expression may indicate various emotions depending on
accompanying gestures and body language. People often use non-verbal signals
unconsciously, such as glancing at a watch to signal impatience. Non-verbal
communication also varies by culture; for example, sticking out the tongue has
different meanings across cultures. NVC reflects attitudes and emotions and can
be more revealing than spoken words. While we can control facial expressions to
some extent, it is harder to hide emotions through voice and gestures. Dialects and
accents in speech can also influence how communication is perceived and
understood.

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 Fig 56 - Verbal and Non-Verbal Communications

FUNCTION OF COMMUNICATIONS
As a manager you must be able to:
- Motivate people and get them going
- Instruct people in the task to be done
- Explain any problems that might be met
- Advise on the control and correction of others activities
- Know what is going on
- Listen to other's ideas and opinions

To do all these, a range of vocal skills and techniques will be needed. The
communication can then take the form of:
- Direct Instructions.
- Talks and Speeches.
- Lessons and Lectures.
- Interviews.
- Group Discussions and Meetings.

COMMUNICATION FAILURES
Communication Failures occur:
- When the technique of communication and the objectives become confused.
- If there is too much talking and not enough listening by managers.
- When there is lack of definition in the management structure leading to
difficulties in responsibilities
- In the understanding of Human Behaviour. Believing Man to be logical and
independent; not sufficiently appreciating his emotional, social and group
needs.
- When insincerity is shown i.e. not believing in what you are saying, and
adopting as fact.
- When insincerity is shown i.e. not believing in what you are saying, and
adopting as fact.

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 - Too often when we speak and think afterwards, realizing from the reactions
given, we have made a mistake.
- If there is ambiguity in the message. When I nod my head, you hit it.
- Inattention - not focusing your mind fully to the person's message.
- When there is lack of FOLLOW UP ACTIONS to verify the instructions
given.
- In our overconfidence that our information if fully understood, 70% of our
communication is misunderstood, rejected, distorted or forgotten.
- When information is left out, to come up with any meaning we have
abstracted.

WORKLOGGING & RECORDING

English is the international language for aviation, but national languages are used
for manuals and documentation within the country of manufacture. When aircraft
operate in different countries, all documentation, including logbooks, must be in
English. Any foreign language logbooks are retained but not used for active
maintenance.
Effective communication in aviation is crucial and must be clear, concise, and
error-free. Training ensures that certifiers can communicate effectively in written
English, essential for interactions across teams, companies, and authorities.
Maintenance work instructions, typically provided by maintenance control in work-
packs, must be followed precisely to ensure compliance and accurate progress
tracking. Adherence to company procedures is mandatory to maintain safety and
efficiency.

Fig 57 - Aircraft Maintenance Manual

DOCUMENTATION
Job Cards and Work Sheets should be designed to encourage progress tracking
with signatures at each stage, and should include clear, straightforward instructions
71
to avoid ambiguity. The forms should be simple yet sufficient for recording all
necessary information, with legible text and ample space for entries. All work
recorded must align with the Approved Maintenance Manual and follow proper
numbering systems, including adherence to Service Bulletins, Airworthiness
Directives, and Notices. Routine tasks have pre-printed worksheets, while non-
routine tasks require licensed engineers to complete sheets meticulously.
Technical information must come from approved publications, and it is crucial for
the Certificate of Release to Service issuer to ensure these are accurate and up-to-
date. Errors in documentation should be reported to company publications or
Aircraft Customer Services, and engineers must stay informed of company
procedures and report discrepancies through the appropriate safety channels.

Fig 58 - Task Card

KEEPING UP TO DATE, CURRENCY

UPDATING
Aircraft engineers must stay current with the latest service bulletins, amendments,
and technical updates. Awareness of these changes is facilitated through company
notice boards, distributed amendments, and signatures for proof of reading.
Engineers should also keep up with advancements in technology and techniques
by reading industry periodicals, watching technical programs, and attending

72
specialist courses. Incorrect component assembly due to not consulting manuals is
a major cause of accidents, highlighting the importance of reading instructions
thoroughly before starting any task. Manuals, service bulletins, and other relevant
documents should be reviewed in advance, and if needed information is missing,
work should cease until it is obtained. Regularly reading manuals during less busy
periods can enhance subject knowledge and improve future reference.

DISSEMINATION OF INFORMATION

In aircraft maintenance, information flows between Manufacturers, Regulatory

Bodies, Operators, and Licensed Aircraft Engineers. Dissemination of this
information, which can be general or technical, occurs through various methods
such as circulars, notice boards, posters, charts, and digital media. Critical
information, especially safety-related, requires feedback confirmation through
signed action slips to ensure all relevant personnel are informed and understand
the updates.
Licensed Aircraft Engineers must stay updated on Service Bulletins, Manual
Amendments, Airworthiness Directives, and Notices relevant to their tasks. They
are responsible for sharing their knowledge within their company and reporting
potential safety issues to Airworthiness Authorities and Manufacturers via the
Mandatory Occurrence Reporting Scheme.
Accident and incident details are published anonymously in periodicals to prevent
future occurrences. Confidential reports can be submitted to organizations to
maintain privacy and encourage reporting.

Fig 59 - EASA Occurrence reporting scheme

SHIFT HANDOVERS
At the point of shift change, the need for effective communication between the
outgoing and incoming personnel in maintenance is extremely important. The

73
absence of such effective communication has been evident in many accident
reports from various industries, not just aircraft maintenance.

IMPORTANT CONCEPTS
Effective shift handover relies on three key elements: the outgoing person's ability
to clearly communicate important task details, the incoming person's capacity to
understand and assimilate this information, and a formalized process for
exchanging information. Each individual must take personal responsibility for their
tasks, ensuring they are completed correctly even if they span shifts. This requires
avoiding the mindset of "It didn’t happen on my shift." Formality is crucial, with
procedures defined in the Maintenance Organization Exposition (MOE), and
managers and supervisors committed to ensuring effective communication across
shifts.

SHIFT HANDOVER EFFECTIVE COMMUNICATION

Effective shift handover communication involves using multiple methods—written,
verbal, and nonverbal—to minimize errors and ensure clarity. Redundancy in
communication methods helps reduce the risk of miscommunication. Feedback
mechanisms, allowing for two-way communication, are essential for verifying
understanding. Handover processes should account for variations in experience
and potential changes during absences, which may extend the duration of
handovers. Properly designed documents, like handover logs, tailored to the needs
of users, improve communication accuracy and acceptance.

BARRIERS TO EFFECTIVE COMMUNICATION

Barriers to effective communication during shift handovers include the presence of
irrelevant information, limitations in processing capacity, and inherent ambiguities
in language. To overcome these barriers, it’s crucial to present only key information
clearly and ensure two-way communication for clarification. Misunderstandings
should be identified and addressed promptly. Organizations should combat
complacency by emphasizing the risks of miscommunication and enhancing the
communication skills of staff. Shift handovers should start early, with continuous
documentation throughout the shift, and include at least two meetings: one for
managerial updates and another for detailed job-related discussions.

Fig 60 - Shift handover meetings

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WALKTHROUGH
After the shift managers' meeting and task assignment, supervisors and certifying
staff should conduct a "Walkthrough" to exchange detailed information about
individual jobs. This involves the incoming and outgoing personnel physically
inspecting and discussing the tasks on the hangar floor or at the workplace,
ensuring clear communication and understanding of the tasks at hand.
The following lists the sort of topics that should be covered in the supervisors /
certifying staff's walkthrough meeting:
- Jobs/ tasks in progress
- Work cards being used
- Last step(s) completed
- Problems encountered
- Outstanding/ in work / status
- Solved
- Unusual occurrences
- Unusual defects
- Resources required / available
- Location of removed parts, tooling etc.
- Parts and tools ordered and when expected
- Parts shortages
- Proposed next steps
- Communication with Planners, Tech Services,
- Workshops
- Communication with managers, etc.

TASK HANDOVER
Task handovers can occur both at shift changes and during ongoing shifts. This
process involves two key scenarios: when transferring tasks to someone currently
present and when stopping a job partway through.

ACCIDENT – EXAMPLE

ABSENCE OF COMMUNICATION IN THE HANGAR

On September 11, 1991, an Embraer 120 with 14 people on board experienced a
fatal accident due to the loss of its left horizontal stabilizer leading edge, which
caused the aircraft to break up in flight. The incident occurred because 47 screws
that were supposed to secure the stabilizer were missing. The missing screws
resulted from a rushed and poorly executed maintenance procedure: the left
stabilizer de-ice boot was replaced during the night shift, but the aircraft was
pushed outside without proper lighting. Consequently, the left side was left
incomplete and was signed off as serviceable, leading to the catastrophic failure.

WHY DID IT OCCUR?

The accident occurred due to a critical lack of communication between shifts.
There was no verbal handover or documentation to indicate that the top screws of
the left horizontal stabilizer had been removed. Additionally, the right stabilizer was
75
reinstalled in inadequate lighting, making it impossible to see the top of the
stabilizers from the ground. The absence of an independent inspection and
incomplete paperwork, which only referenced the right side, further contributed to
the oversight, leading to the fatal failure.

SO, WHAT CAN BE DONE TO PREVENT A RECURRENCE?

A greater awareness of the importance of communication - both verbal and written-
is a must if accidents are to be avoided. Any work done that isn't covered on a
work-card must be written up. 'Assuming has no place in our business'.

HUMAN ERRORS

ERROR MODELS AND THEORIES

Maintenance errors, long a factor in aviation accidents, have become more
prominent as aircraft reliability improves and Cockpit Resource Management gains
traction. High-profile incidents, such as the American Airlines DC-10 crash in 1979
and the F-28 crash in 1989, highlight how improper maintenance procedures and
human factors can lead to catastrophic outcomes. Investigations into these
accidents often overlooked the human elements in favor of focusing on system
failures. The need for human factors training became evident, leading to efforts like
those by Gordon Dupont to develop programs aimed at reducing maintenance
errors. While training in human factors is crucial, it is just one part of a broader
strategy that must include other safety measures and awareness to effectively
reduce errors and improve overall safety.

COMPANY CULTURE
Company culture reflects the values and leadership styles of a company’s leaders,
influencing how these values are interpreted by middle management and acted
upon by employees. A strong, positive company culture can significantly reduce
maintenance errors by shaping norms and behaviors. According to James
Reason's model, adapted by Gordon Dupont, management decisions and latent
conditions play crucial roles in error prevention. Modern regulatory bodies and
companies focus not just on active failures but also on identifying and addressing
latent conditions that can contribute to maintenance errors.

Fig 61 - Company Culture

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 Fig 62 - Human errors simulation

ACTIVE ERRORS/FAILURES
Active errors are made by the person at the end of a line of contributory
circumstances.
For example:

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 Fig 63 - Maintenance Errors

In recent years, the trend of accidents has been decreasing, with pilots' failure to
follow standard operating procedures being the most frequent factor. Maintenance
errors account for about 4% of accidents, although this figure may vary. However,
mistakes leading to accidents are not confined to line personnel; they can also
originate from different levels, such as design or production errors by
manufacturers, planning or resource allocation mistakes by airline management,
and improper oversight by regulatory bodies. These so-called 'Latent Errors' are
often hidden within the system and can combine with 'Active Errors' to result in an
accident.

Fig 64 - Latent Errors

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LATENT FAILURES
Latent failures are due to management failing to recognise and deal with the
following, any of the following which could result in a future hazard:

RESPONSIBILITIES
Mistakes are inevitable, including those made by managers, who often contribute
to latent failures that only surface during accidents. While management may not be
directly responsible for active failures, they play a significant role in preventing
latent errors. Statistics suggest that there are about three times as many latent
failures as active ones, making their identification crucial for enhancing safety.
Management has a 'Prime Responsibility' for safety, which influences the entire
company's culture. A strong safety culture begins with a 'Safety Policy,' prominently
displayed and signed by the CEO, emphasizing that every employee must adhere
to and report on the safety policy to ensure continuous improvement.

HUMAN FACTORS INCIDENT INVESTIGATION

ICEBERG MODEL
The Iceberg Model, derived from Heinrich's ratio, highlights that for every fatal
accident, there are approximately 600 incidents, illustrating that accidents are the
result of numerous prior incidents. To improve safety, it's crucial to record and
analyze human errors and incidents in a manner similar to tracking aircraft
components. A thorough 'human factors' investigation should be conducted for
significant incidents to identify root causes, with criteria set to trigger these
investigations. Investigators should be trained, trusted, and involved in
implementing findings. Effective safety improvement depends on acting on these
recommendations and fostering trust between investigators, management, and
employees.

Fig 65 - The Iceberg Model

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DISCIPLINE
In the aircraft industry, international and national regulations are enforced to
ensure safety, and discipline is sometimes used to uphold regulatory authority and
deter violations. The Civil Aviation Authority (CAA) handles various cases annually,
with a significant portion leading to prosecutions or formal cautions, often related to
falsified maintenance records. A key aspect of Human Factors programs is to
encourage individuals to confess breaches without fear, promoting a culture of free
reporting. This openness helps avoid severe consequences and aids in safety
improvements. For instance, punitive measures against an employee who took a
shortcut to meet a deadline can lead to resentment and reduced morale,
highlighting that while discipline might achieve compliance, it can also have
negative impacts on motivation and teamwork.

DISCIPLINE OR NOT
To determine if discipline is necessary, consider these key questions: Was the act
deliberate? If so, discipline is warranted, but the underlying reasons should be
examined. Does the person accept responsibility? If they blame external factors,
discipline may be appropriate. Is the person likely to repeat the behavior? If they
accept responsibility and show commitment to change, discipline might not be
needed. Involving the employee in addressing the root cause can transform a
situation from a LOSE/LOSE to a WIN/WIN scenario, provided there is trust at all
levels.

INCIDENT/ ACCIDENT DATA ANALYSIS

Data analysis in incident and accident management is crucial for improving aircraft
maintenance and operations. It moves decision-making beyond intuition, providing
concrete evidence on the effectiveness of safety measures and training programs.
By analyzing recorded data, companies can identify training needs, assess the
impact of Human Factors awareness, and measure cost benefits. A future global
database of reported incidents could enable the development of strategies to
reduce maintenance errors by learning from past incidents and predicting potential
future issues.

Fig 66 - Data Analysis

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FEEDBACK
Feedback is essential for improvement and morale in any organization. Research
on mice shows that isolation leads to negative outcomes, highlighting the
importance of feedback and communication. Positive feedback and sharing
lessons from errors help prevent repetition of mistakes and foster a learning
culture. Company newsletters are vital tools for informing, educating, and
motivating employees, featuring educational articles, responses to inquiries, and
performance statistics to keep everyone engaged and informed.

Fig 67- Feedback Teams

MODELS DESCRIBING HUMAN FACTORS

In order to simplify the relationship between engineers and the factors which
impact upon their everyday working lives several models have been produced,
examples of which are: The 'SHEL' Model, Reason's 'Swiss Cheese' Model and
The Weakest Link.

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THE 'SHEL' MODEL
This model shows the interfaces between the human, being the 'L' in the centre
box and the other elements of the SHEL model, e.g.:
- 'S' for software being the interpretation of procedures, illegible manuals,
poorly designed checklists, ineffective regulation, untested computer
software etc.
- 'H' for hardware meaning not enough tools, inappropriate equipment, and
poor aircraft design for maintainability etc.
- 'E' for environment meaning your working environment which may involve
an uncomfortable workplace, inadequate hangar space, variable
temperature, noise etc.
- 'L' for live ware meaning poor morale, relationships with other people,
shortage of manpower, lack of supervision, lack of support from managers.

However, the model also accepts that sometimes the 'L' in the centre box can
stand alone, and there can be problems associated with a single individual which
are not necessarily related to any of the L-S, L-H, L-E, L-L interfaces.

Fig 68 - The 'SHEL' Model

REASON'S 'SWISS CHEESE' MODEL

James Reason's "Swiss Cheese" model uses slices of Swiss cheese to represent
different organizational activities or departments, with holes in the cheese
symbolizing gaps in defenses. Errors that aren't caught at the source may be
addressed by subsequent layers, but occasionally, an error can pass through all
defenses and lead to an accident. The goal is to improve each department's
defenses, transforming their slice from Swiss cheese with holes into the more
robust "Farmhouse Cheddar," which represents a well-protected system.

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 Fig 69 - Swiss Cheese Method

THE WEAKEST LINK

The concept of "The Weakest Link" underscores that the safety of an aircraft relies
on the collective effort of many individuals, each performing crucial tasks. The
overall strength of this chain is determined by its weakest link, as any failure in one
part can lead to catastrophic results. For an incident to occur, latent failures
(underlying issues) must combine with active failures (errors) and local triggers
(such as environmental conditions). For example, a worn brake pedal combined
with wet conditions and engineer distraction can lead to a serious incident. While
many unsafe acts occur daily, they are often caught or mitigated by system
defenses. Thus, while engineers are diligent in their efforts to maintain safety, the
integrity of the entire system depends on addressing and strengthening every
potential weak link.

Fig 70 - The Weakest Link

ACTIVE FAILURE
Active Failure refers to mistakes made by individuals, such as pilots, engineers, or
ramp staff, which can lead to accidents if not mitigated by safety nets. These errors
often occur due to underlying latent conditions—hidden problems that may only
become apparent when human errors occur. For instance, incorrect installation of
parts or failure to follow maintenance manuals can lead to significant safety risks.
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Analysis of Mandatory Occurrence Reports (MORs) shows that active failures,
such as incorrect installations, frequently contribute to safety issues. If unsafe acts
are not addressed, they can escalate into serious accidents.

INADEQUATE SAFETY NETS/DEFENCES

Inadequate Safety Nets/Defenses refer to the lack of measures designed to
mitigate the consequences of human errors in aircraft operations. Despite the skill
and diligence of individuals, errors are inevitable. To protect against these errors,
safety measures such as built-in redundancy, damage tolerance, and special
checks (including duplicates and functional checks) must be implemented. These
defenses help prevent errors from leading to accidents by providing additional
layers of protection.

TOLERANCE/REDUNDANCY
Tolerance/Redundancy in modern aircraft design ensures safety by incorporating
multiple load paths and duplicating critical systems. Components critical to safety
are given a "Safe Life," indicating their reliability is extensively tested to minimize
failure risk. The semi-monocoque construction, using frames and stressed skins,
provides multiple load-bearing paths, enhancing damage tolerance. Vital systems,
such as powered flight controls, often feature redundancy to prevent failure. For
example, a multi-wheeled landing gear can function even if one tire fails, and
systems protect against voltage fluctuations. While some faults can be tolerated,
critical components that could cause catastrophic failure require rigorous checks
and maintenance.

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 Fig 71 - Redundancy of the hydraulic power

CHECKS/DUPLICATE INSPECTIONS
Checks/Duplicate Inspections are crucial for ensuring aircraft safety. Ideally, no
individual should work or certify alone; pairing up provides additional oversight and
reduces errors. Complex tasks often involve stage inspections, where an inspector
supervises and certifies the work done by others. The work pack preparation team
and inspectors determine the required depth of supervision and special checks
needed. For instance, before closing a fuel tank, cleanliness checks are
mandatory, and for critical systems like engine controls, EASA mandates
independent inspections. An independent inspection involves one qualified
engineer performing the work, followed by a second engineer repeating the
inspection to prevent incorrect component installation and ensure accuracy.

FUNCTIONAL TESTS
Functional Tests are essential after any component change, regardless of the
procedure's simplicity or the engineer's skill. These tests verify if components like
hydraulic non-return valves or flying controls are correctly installed and functional.
Although they may not detect all workmanship issues, such as dry soldered joints
or slack turnbuckles, they are crucial for ensuring that systems meet operational
standards. Built-in test circuits for electronic systems can also be part of the
functional testing process. Overall, functional tests are a critical step in confirming
that maintenance tasks meet required serviceability standards.

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TYPES OF ERROR IN MAINTENANCE TASKS

Human error is an inevitable part of life, with most mistakes being minor and easily
corrected, such as burning toast or dialing the wrong number. However, in
maintenance, errors can have severe consequences and may not be easily
detected or corrected. While studies can estimate the overall probability of errors,
predicting when and where they will occur is challenging. Human error is a
dynamic threat due to human adaptability, requiring ongoing management and
adaptation of solutions. Errors can remain hidden in systems for extended periods,
surfacing only during critical moments, as seen in historical accidents like the
Boeing 747 rear bulkhead failure. Despite the low frequency of severe
maintenance errors, many errors are corrected without documentation or reporting,
leaving gaps in learning and improvement. The decline in general errors over time
reflects advancements in machine reliability, but changes in human behavior and
error reduction have not evolved as rapidly.
Different statistics involving the maintenance error distribution all show that in
general the amount of the hardware caused events is gradually falling over the last
20 years, but the amount of the Human Factor related events is decreasing with
much slower rate. To summarise the most probable causes for errors in aviation
maintenance environment:

- Check for errors in another person work

- Incorrect Installation of Components.
- Fitting of Wrong Parts.
- Electrical Wiring Discrepancies.
- Loose Objects left in aircraft.
- Inadequate Lubrication.
- Access Panels/Fairings, Cowlings not secured.
- Fuel/Oil Caps and Fuel Panels not secured.
- Gear Pins not removed before departure.

Fig 72 - Incorrect repair of the aft bulkhead on B747

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 Fig 73 - Overall aviation type of errors

Fig 74 - Percentage of the aviation maintenance occurrence

involving events

IMPLICATIONS OF ERRORS
Human error at any stage of aircraft design, manufacture, maintenance, or
operation can lead to accidents, with Heinrich's Ratio suggesting that one fatal
accident follows 600 incidents. These accidents incur significant costs for the
owner/operator and insurance companies, including hull loss, property damage,
and personal liability, which are recoverable. However, non-recoverable costs
include insurance deductibles, higher premiums, loss of aircraft use, accident
investigation expenses, schedule disruptions, and the hiring and training of new
personnel. The impact on company reputation and public trust is harder to quantify
but can be severe, affecting future business and workforce morale. For example,
after two B737-MAX crashes in 2019, Boeing faced substantial reputation damage

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and a decline in public trust, illustrating how accidents can have far-reaching,
costly consequences beyond the immediate financial impact.

AVOIDING AND MANAGING ERRORS

The aviation industry has long prioritized safety, leading to advancements such as
safer aircraft designs, system redundancy, improved working practices, and
enhanced training and regulations. Despite these efforts, the accident rate per
million flight hours has plateaued, with predictions of a major airliner accident
weekly by 2010. The high-profile nature of aircraft crashes and their impact on
public trust underscores the need for a comprehensive approach to error reduction.
To address this, Safety Management Systems (SMS) have been introduced,
becoming mandatory for Part-145 maintenance organizations by the end of 2024.
Over the past 15 years, SMS implementation across various aviation sectors has
significantly improved safety and reduced fatal accidents, even as air traffic has
increased.

Fig 75 - Safety Management System (SMS)

REGULATIONS
Regulations mandate that maintenance organizations establish minimum safety
standards. However, human performance can fall short of these standards, leading
to potential sub-standard work. To mitigate this risk, companies should set their
own higher standards, especially for tasks with significant risk, to ensure safety
beyond the regulatory minimum.

PROCEDURES
Procedures alone do not solve problems unless used systematically and reviewed
regularly. They should be updated to ensure accuracy and safety. Many
companies lack effective systems to investigate and monitor incidents and trends,
often due to a weak safety culture. Without learning from past incidents, companies
are prone to repeat the same problems.

HUMAN ERROR
Human error is the primary issue in flight safety. Typically, individuals do not intend
to make mistakes; instead, errors result from a mix of systemic issues and
cognitive limitations, often under perceived pressure. Addressing this requires
changes in management attitudes and new approaches to handling human error.
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ORGANISATIONAL ERRORS
Errors often stem from organizational issues rather than single causes.
Organizations must adapt to industry changes, which can introduce new risks.
Modern organizations use Management of Change (MOC) practices to manage
these risks effectively. MOC helps predict and mitigate potential problems arising
from organizational changes, such as expanding facilities.
MOC is essential for ensuring safety during transitions, protecting workers, and
complying with aviation and safety regulations. It involves assessing the risks of
proposed changes and implementing measures to address them. This proactive
approach helps prevent negative impacts on personnel, operations, and the
environment, ensuring that changes bring benefits without compromising safety.

Fig 76 - Organizational influence to errors

LIABILITY
Company executives and board members must be aware of their corporate liability,
including the risk of charges like Corporate Manslaughter. Aviation is costly, and
accidents can lead to significant financial losses, potentially bankrupting a
company. To mitigate this risk, boards need to understand their legal and financial
responsibilities and implement a robust Safety Management System (SMS) to
enhance safety and reduce the risk of accidents.

SAFETY MANAGEMENT

AVOIDING AND MANAGING ERRORS

SAFETY CULTURE
Safety culture in aviation encompasses the shared beliefs, values, and rules—both
formal and informal—that define an organization's commitment to safety. It reflects
the company's true dedication to safety from top leadership down to every
employee and determines how safety is prioritized in practice. This holistic
approach includes safety management, employee responsibilities, the relationship
between management and staff, and the structure of the Safety Management
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System (SMS). It is essential for protecting passengers, ground personnel, and
maintenance technicians. Effective safety culture involves all members of the
organization, with success measured through anonymous surveys, the
appointment of a safety director, and using survey results to address any
shortcomings. An active safety culture helps prevent complacency and promotes
ongoing commitment to safety, benefiting the entire organization.

Fig 77 - Safety culture elements

JUST CULTURE
A "Just Culture" is essential for fostering an effective safety culture within aviation
organizations. It balances the need for reporting and learning from safety-related
incidents without fostering a punitive environment. In a Just Culture, individuals are
encouraged to report errors and safety issues without fear of undue punishment,
though deliberate unsafe acts, such as criminal behavior or gross negligence, are
still subject to appropriate sanctions. This culture promotes transparency and trust,
facilitating the investigation of both major and minor occurrences to prevent future
incidents. Key features of a Just Culture include clear definitions of acceptable and
unacceptable behavior, documented policies, fair treatment, and effective
communication throughout the organization. By ensuring that safety issues are
reported and addressed fairly, a Just Culture helps improve safety awareness and
effectiveness.

Fig 78 - Just culture

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RISK MANAGEMENT
Risk management involves identifying, analyzing, prioritizing, and controlling risks
that could impact an organization's safety, quality, and financial objectives. The
process starts with identifying potential risks, analyzing their impact, prioritizing
them based on their significance, implementing control measures, and
continuously monitoring the risks. Effective risk management requires
comprehensive documentation and administration. Day-to-day operations must
align with safety requirements, and all employees should understand their
responsibilities.
Workplace hazards must be identified and eliminated to prevent incidents or
fatalities. A risk register helps track safety-critical activities and associated hazards,
listing responsible parties and necessary controls. The register should be updated
regularly to incorporate new technology and regulations. Sharing information about
hazards between organizations can help mitigate risks, though legal
responsibilities may vary. For example, while fuel suppliers ensure quality and safe
delivery, ground crews manage its correct use and storage.

Fig 79 - Risk management process

DEVELOPMENT OF THE HAZARD MODEL

To identify and manage aircraft hazards, a workshop with pilots and engineers
should be organized to form an expert panel. Once a hazard is identified,
appropriate physical, organizational, or procedural controls must be implemented
to prevent its unplanned release. For instance, working on the top of a vertical
stabilizer is a controlled hazard managed by using safety precautions and personal
protective equipment (PPE). If safety procedures are neglected, such as forgetting
to strap into a safety rope, the risk of an accident increases, depending on the
individual's skills and awareness.

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Controls, including procedural, organizational, and physical measures, are
essential but must be supported by training, assurance, awareness, and
accountability. Hazard management employs tools like the Bow-tie Analysis and
risk matrices, which address both proactive and reactive measures.

Proactive Measures:
- Identify the hazard and potential threats.
- Establish threat controls to prevent hazard release
- Identify escalation factors that could weaken these controls.
- Assess and implement escalation controls.
- Define the hazardous event.

Reactive Measures:
- Assess recovery measures to return to normal conditions.
- Identify factors that could hinder recovery.
- Establish escalation controls to maintain recovery.
- Evaluate potential consequences of failed controls.
- Implement damage limitation strategies.

These tools and processes ensure effective hazard management and safety in
aviation operations.

Fig 80 - Hazard Model

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 Fig 81 - The Bow Tie

USE OF RISK MATRIX - SEVERITY/LIKELIHOOD MODEL (5X5 RISK MATRIX)

The analysis carried out using the risk assessment matrix will be a measure of
'How bad can it be and how often will it happen?'.
From this, the company can judge what action is required. Low risk with little
probability of occurrence will be managed through normal health and safety at work
procedures. If the circumstances of a hazardous event are significant and there is
a likelihood of its occurrence, then risk reduction measures should be taken, as
reasonably practicable, to reduce the risk to low.

Fig 82 - Example of a Risk assessment matrix

SAFETY ISSUE RISK ASSESSMENT (SIRA)

Safety Issue Risk Assessment (SIRA) methodology is used during safety
investigations to analyse the event itself or each separate barrier to determine their
effectiveness and/or to understand why the barriers failed.

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 Fig 83 - Example of the hazard (event) risk classification

Based on risk assessment the risk severity and likelihood are defined in the matrix
and based on that further on the actions to be taken can be defined
Based on the risk assessment results, the risk tolerability levels are classified. Risk
tolerability table can help us in that manner

Fig 84 - Risk tolerability

The risk mitigation is carried out on basis of the defined Risk tolerability. If the risk
is Unacceptable the operation must be stopped immediately and mitigation
measures must be taken.

In risk management, if a risk is deemed Tolerable, operations may proceed, but

mitigation actions are necessary. If a risk is Acceptable, no immediate action is
required, though monitoring is recommended. Mitigation actions include:
- Avoidance: Canceling or avoiding the operation or activity.
- Reduction: Minimizing the frequency or impact of the risk.
- Segregation: Isolating the effects or building redundancy to protect against
the risk.

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To manage risks effectively, barriers like "Avoidance Barriers" and "Recovery
Barriers" are used, determined through risk assessments and addressed by
responsible personnel. Properly implemented mitigation actions should reduce or
eliminate risks, though complete elimination is rare. Mitigation measures should be
technically feasible, reasonable, and not financially burdensome.
Aviation involves analyzing numerous hazards, many of which relate to Human
Factors. Identifying hazards and hazardous events typically reveals existing
controls and their effectiveness, highlighting areas for improvement.

ALARP
In risk management, achieving absolute safety is not feasible; instead, risks are
managed according to the ALARP principle—'As Low as Reasonably Practicable.'
This means risks are reduced to the lowest level possible, considering practical
limits and costs. A risk is deemed tolerable if the benefits outweigh the costs of
additional safety measures. To assess if a risk is ALARP, organizations evaluate:

- Legal Requirements: Compliance with regulations, such as CAA guidelines.

- Expert Judgment: Controls are deemed reasonable if experts agree on their
safety benefits and costs.
- Cost-Benefit Analysis: Analyzing if the cost of a control is disproportionate to
its safety benefit.
- Industry Good Practice: Controls aligned with established best practices are
considered reasonably practicable.

MONITORING OF THE MITIGATION ACTIONS

Once mitigation actions are assigned by the Safety Department to the responsible
person or safety expert, it is the Safety Department’s role to monitor their
implementation and evaluate their effectiveness.

TREND MONITORING AND ANALYSES

To track the effectiveness of mitigation actions, it is crucial to monitor risks and
analyze trends using Key Performance Indicators (KPIs) or Safety Performance
Indicators (SPIs), along with Safety Performance Targets (SPTs). These indicators
help assess safety performance over time and determine whether the implemented
actions have led to improvements. If KPIs or SPIs do not show the desired
progress after a set period, the hazards should be re-evaluated, and new mitigation
actions should be established, restarting the safety assessment process.

INVESTIGATIONS WHERE HUMAN FAILURE OCCURS

Investigations into human failures in aircraft maintenance have led to several key
conclusions from the Air Accident Investigation Branch:

- Procedure Adherence: Even well-trained and experienced engineers

sometimes make errors by not following company procedures and manuals,
despite being expected to perform optimally and procedurally.

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 - Critical Maintenance Tasks: These tasks should have safeguards to prevent
failure through a single point of error.
- Self-Certification Assumptions: Current philosophies of self-certification and
company approvals assume that suitably trained and equipped individuals
will avoid significant errors, which may not always hold true.
- Quality Systems Focus: Quality assurance often emphasizes paperwork
over the actual completion of maintenance tasks.
- Night Shift QA: Quality assurance might be neglected during night shifts.
- Complexity of Modern Aircraft: The growing complexity of modern aircraft
may require a more meticulous approach to maintenance, which could be
met with resistance from current engineers.

PROGNOSIS
The avoidance of future unnecessary accidents depends on an attitude of total
compliance being fostered and developed, since it is not possible for maintenance
staff to have enough information to understand the consequences of any deviation
from Approved Data. This requires a major cultural change.

OCCURRENCE REPORTING

Occurrence reporting under EASA Part-145 regulations addresses significant

technical or airworthiness issues found on aircraft, such as structural cracks.
Safety reporting, however, focuses on improving aviation safety by systematically
reporting, collecting, analyzing, and safeguarding relevant safety information. Both
reporting systems often follow similar processes.
Occurrence and safety reporting should cover incidents, malfunctions, technical
defects, and other irregularities that may endanger aircraft safety but do not result
in accidents or serious incidents. The Safety and Quality Department
independently manages the collection and analysis of these reports, while
department heads are responsible for addressing safety reports to mitigate risks.
Confidentiality and a 'just culture' are crucial, ensuring that reports are used solely
for safety improvements. The safety reporting scheme complements existing
procedures and control systems, aiming to identify where control systems have
failed without duplicating or replacing established procedures.

MANDATORY REPORTING
Mandatory reporting requires all staff to report any safety event affecting or
potentially affecting aircraft safety, regardless of injury or property damage.
Reports must be made as soon as possible, but no later than the end of the shift.
For significant safety risks, the Civil Aviation Authority must be notified
immediately, followed by a detailed report within 72 hours. For less urgent risks,
reporting can be delayed up to 72 hours to gather more information.

VOLUNTARY REPORTING
Voluntary reporting systems allow staff to report safety events, hazards, fatigue,
human errors, unsafe acts, and violations not covered by mandatory reporting. This

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system encourages the collection of additional safety data and helps improve
safety without placing blame. Reports can be made anonymously or confidentially,
protecting the reporter's identity to foster open communication and learning.

FEEDBACK TO THE REPORTER

Reporter shall always be given a feed-back from the investigation process and
results that come out of the investigation process. Reporting is never one-way
road, but must - using the feedback - close the loop between the safety
investigation and reporter.

ORGANISATIONAL HUMAN-FACTORS PROGRAMME

PROFESSIONALISM AND INTEGRITY

Aviation engineers must uphold high professionalism and integrity, prioritizing
safety over personal gain. Professionalism involves adhering to strict standards
and ethical boundaries, avoiding rule-bending. Engineers should avoid error-
provoking environments that lack proper controls, which can lead to unsafe acts.
Examples of provocative behaviors include cutting corners, certifying incomplete
tasks, superficial inspections, poor rest, using unofficial documentation, relying on
memory, and substance abuse. Maintaining professionalism ensures adherence to
safety and prevents errors.

ASSERTIVENESS
Assertiveness at the company level involves actively identifying and addressing
issues before they escalate. It means being attentive to daily actions, stopping
improper behavior early, and discussing or reporting it as needed. Assertiveness
entails expressing feelings, opinions, and needs in a positive, non-aggressive
manner, and it also involves respecting others' requests and refusals. It requires
backing up arguments with documentation and facts while remaining open to
different perspectives. Assertiveness helps prevent small errors from becoming
serious problems.

Fig 85 - Being assertive means not being aggressive or passive

DISCIPLINARY POLICY
The disciplinary policy of an organization is designed to address employee
misconduct following an investigation, adhering to "just culture" principles. It aims
to correct behavior rather than punish and involves clear, consistent rules. The

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policy should specify the conduct that is acceptable and the consequences of
violations, ensuring that rules are clear, communicated effectively, and applied
fairly. It should consider the intent, recklessness, knowledge, and negligence of the
misconduct. The disciplinary system must involve both management and employee
representatives to ensure fairness, and be managed by trained personnel.
Adherence to these principles and proper disciplinary management are key
indicators of a strong safety culture.

DEALING WITH EMERGENCIES

It can be foreseen and it can be planned for, but there will be no warning. This is
why emergency drills are practised.

ACTION IN CASE OF EMERGENCY

In an emergency, the first person aware of the situation must promptly raise the
alarm and activate the emergency stop system if necessary. The primary goal is to
prevent loss of life, further injury to victims, or harm to others. For fires, follow the
designated drill procedure. In case of an accident, shut down the cause (e.g.,
machinery, power, gas) and seek help. Know who is qualified to administer first aid
and report any injuries, no matter how minor, to the first aider. Report any hazards
that could lead to accidents.

SAFETY

Safety relies on the principle "A place for everything and everything in its place,"
which is grounded in common sense. This involves:

- Keeping gangways clear of obstacles to avoid tripping hazards.

- Ensuring machinery is guarded to protect against moving parts.
- Avoiding sharp or pointed tools left carelessly around.
- Being able to find items quickly, especially in emergencies.
- Cleaning up spilled liquids or grease to prevent slips and delays.

Maintaining order and cleanliness reduces the risk of accidents and ensures swift
response during emergencies.

HAND TOOLS
Injuries from hand tools often result from carelessness, distraction, or poor
handling. It's important to use hand tools properly and focus on the task to prevent
accidents. Safety is key to avoiding injuries and maintaining a safe work
environment.

HORSEPLAY
Horseplay is highly dangerous and prohibited. Equipment like compressed air guns
can be as lethal as firearms and must be handled with respect and caution. Always
focus on using equipment safely to prevent accidents and injuries.
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ELECTRICITY
Electricity is powerful and dangerous, often made less obvious by its invisibility.
Always assume that electrical equipment is live and never rely solely on visible
indicators. Ensure proper protection for all parts of your body and be aware of the
conditions that can lead to accidents. Most accidents are caused by avoidable
mistakes rather than random events.

ACTING IN A CASE OF AN EMERGENCY

In a maintenance environment, while minimizing risks is crucial, everyone must be
prepared to handle emergencies effectively. Participation in emergency drills is
essential, as knowing the correct actions to take can save lives.

Fig 86 - Standard Symbols

WHAT IS AN EMERGENCY?
An injury to oneself or to a colleague; A situation that is inherently dangerous,
which has the potential to cause injury (such as the escape of a noxious
substance, or a fire).

THE RIGHT SUPPLIES

To effectively handle emergencies, it is crucial to have the right supplies readily
available. This includes maintaining first aid kits and other emergency supplies. A
designated Safety Officer should regularly check and replenish these supplies.
Additionally, employees should receive training in emergency preparedness,
including the proper use of equipment and basic first aid and CPR.

EMERGENCY CONTACTS AND COMMUNICATIONS

To prepare for emergencies, ensure that emergency contact information and
communication plans are established. During training, inform everyone about
whom to contact and how. Workers should have access to wireless communication
if needed. Emergency numbers such as 112 (Europe and parts of Asia) or 911
(mostly in America) should be known to connect with local emergency services.

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RESPONDING TO AN EMERGENCY

1- Get to Safety: Move to a safe location to prevent additional injuries.

2- Assess the Situation: Determine if anyone is injured, if property is damaged,
and if emergency services are needed.
3- Call for Help: Contact emergency services, providing your workplace
address, phone number, and direct them to the incident location.
4- Know Emergency Equipment Locations: Familiarize yourself with the
locations of fire extinguishers, alarms, chemical spill materials, and first aid
supplies.
5- Operate Emergency Equipment: Understand how to use fire extinguishers,
safety showers, and eye wash stations.
6- Know Your Limits: For anything beyond basic first aid, involve emergency
medical professionals immediately.
7- Find Safety Data Sheets (SDS): Locate SDS for chemicals to handle spills
or exposures properly.
8- Locate Emergency Exits: Be aware of and know the evacuation routes.
9- Assist the Injured: Provide first aid and stabilize major injuries if possible.
10- Record Information: Document the accident details while they are fresh in
your mind.
11- Preserve Evidence: Do not destroy evidence; it is crucial for preventing
future accidents.
12- Prevent Further Accidents: Take immediate action to prevent additional
injuries and assess for long-term changes with the Safety Committee.
13- Follow Up: Complete any required paperwork and support requests from the
Safety Committee or management.

POSSIBLE WORK-RELATED EMERGENCIES

PERSON STOPS BREATHING AND LACKING PULLS

Call emergency number if:
The person stops breathing for longer than 15 to 20 seconds and has severe
trouble breathing, a person with this problem may:
- Have chest tightness so severe that the person is worried she/he can't keep
breathing.
- Be so short of breath that she/he can't speak.
- Gasp for breath or have severe wheezing.
- Feel very anxious, afraid, or restless.

RESCUE BREATHING AND CPR

Doing CPR the wrong way or on a person whose heart is still beating can cause
serious harm. Do not do CPR unless:
- An adult is not breathing normally (may be gasping for breath).
- The person does not breathe or move in response to rescue breaths.
- No one with more training in CPR than you is present. If you are the only
one there, do your best.

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CHEMICAL BURNS
In case of chemical burns, it is crucial to act quickly. Call emergency services if a
strong chemical, such as an acid, splashes into the eye or if a large area of skin
(more than 25%) or any part of the face is exposed to a strong acid or caustic
substance. Seek help if eye pain persists after 30 minutes of rinsing, or if there is
severe redness, discharge, discolored areas in the eye, vision problems, or severe
skin damage (such as redness, blistering, or blackening). Immediately flush the
eyes with plenty of water or an eye wash solution for at least 30 minutes. For skin
burns, use the safety shower. Keep the chemical's container or label nearby to
assist medical personnel in identifying the substance. Continue rinsing until the
pain subsides or help arrives.

HEAD INJURY
Call emergency number if:
- Unconscious for more than a few seconds.
- Severe bleeding does not slow down or stop after 15 minutes of direct
pressure.
- Has a seizure.
- Feels weak or numb on one side of the body.
- Double vision or trouble speaking lasts more than a minute or two.
- Seems confused, does not remember being hurt, or keeps asking the same
questions.
- There is bruising around the eyes or behind one ear.
- There is a new "dent" or deformity on the skull.
The wound need s stitches.
A head injury may be more severe than it appears, with potential internal bleeding
or swelling even if there's no external bleeding. Greater force increases the risk of
serious injury. If the person is unconscious, assume a spinal injury and do not
move them without first stabilizing the neck. Apply firm pressure with a clean cloth
to any bleeding wound for 15 minutes; if the cloth becomes soaked, place another
on top. Be sure to check for and address any other injuries that may be present.

HYPOTHERMIA
Hypothermia occurs when the body loses heat faster than it can produce it, leading
to dangerously low body temperature. It can develop at temperatures as high as
50°F (10°C) in wet and windy conditions, or in water between 60°F to 70°F (15°C
to 21°C). Early signs include severe shivering, confusion, stumbling, and cold, pale
skin. If symptoms like shivering, cold skin, and clumsy movements are present,
warm the person immediately. Remove wet clothes, replace them with dry, warm
clothing, and provide warm fluids and high-energy foods, but avoid alcohol and
caffeine. If the person is confused or unconscious, do not give food or drink. Place
the person in a hypothermia wrap if possible.

SPINAL INJURY
If you suspect a spinal injury, call emergency services immediately. Symptoms
include severe neck or back pain, bruising on the head, neck, shoulders, or back,

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weakness or numbness in limbs, loss of bowel or bladder control, and fainting. Any
neck or back injury can damage the spine, so it's crucial to prevent movement to
avoid paralysis. If you must move the person, do so carefully by keeping the head,
neck, and shoulders aligned as a unit, and only if there's an immediate threat to
life, such as a fire.

STRAIN, SPRAINS AND BROKEN BONES

Call emergency number if:
- A bone is poking through the skin.
- The hurt limb or joint looks odd, is in a strange shape, or is out of its normal
position.
- The skin over the site of an injury is broken.
- Signs of nerve or blood vessel damage, such as:
- Skin that is pale, white or blue, or feels colder than the skin on the limb that
is not hurt.
- ot being able to move the limb normally because of weakness, not just pain.
- Not being able to bear weight on or straighten a hurt limb.
- Severe pain.
- Swelling within 30 minutes of the injury.

Injuries such as fractures, sprains, and dislocations all cause pain and swelling. A
sprain involves damage to ligaments or soft tissues around a joint, while a
dislocation occurs when a bone is forced out of its normal position. Distinguishing
between a strain, sprain, fracture, or dislocation can be challenging without obvious
signs of a broken bone. Rapid swelling often indicates a more severe injury. Minor
strains and sprains can typically be treated on-site, but serious sprains, fractures,
and dislocations require medical attention.

SPLINTERING
Splintering is a short-term first aid measure for broken bones. There are two
methods for splinting a limb:
- Method 1: Tie the injured limb to a stiff object (like rolled newspapers,
magazines, or a stick) using a rope or belt. Ensure the splint keeps the limb
from bending and extend from a joint above the break to below it, e.g., from
above the elbow to below the wrist for a broken forearm. Avoid tying too
tightly.
- Method 2: Tape a broken finger or toe to the adjacent one with padding in
between, or tie a hurt arm across the chest to prevent movement.

THE 'DIRTY DOZEN' AND RISK MITIGATION

THE DIRTY DOZEN

The "Dirty Dozen" refers to twelve key factors identified by Transport Canada in the
late 1980s and early 1990s that impair maintenance performance and increase the
risk of errors in aviation. These factors highlight how organizational, work group,
and individual issues can lead to maintenance-related accidents. The Dirty Dozen

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serves as a tool for understanding and managing human error in maintenance,
emphasizing the need for awareness and proactive strategies to prevent and
address these issues.

Fig 87 - The Dirty Dozen

LACK OF COMMUNICATION
Lack of communication in aviation maintenance can lead to significant errors, such
as missing tasks or incorrectly fitted components. Effective communication is
essential for staying updated with maintenance manuals and service bulletins, and
for ensuring a smooth transition between shifts. Inadequate communication can
result in critical issues being overlooked, potentially compromising aircraft safety.

SAFETY NETS:
- Use log books, worksheets, etc. to record all work that has been completed.
- If there are several stages on a worksheet, sign each task as it is
completed, don't be tempted to 'paper whip' by signing each page as a
complete block.
- At shift change, write a list of all outstanding jobs that need to be completed
and discuss this list with the oncoming shift to remove any doubt as to what
is required.

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 Fig 88 - Lack of communication

COMPLACENCY
Complacency in aviation maintenance arises from routine tasks, leading engineers
to overlook faults due to over-confidence and boredom. This attitude can result in
skipping inspections or signing off tasks without proper checks, increasing the risk

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of errors. Complacency often develops from a lack of dedication and can be
contagious, with potentially serious consequences only becoming apparent after an
accident or incident.

SAFETY NETS:
- Always train yourself to expect to find a fault.
- Even if you have carried out the same job many times before, without
finding a fault, don't think that you will never find one.
- At every inspection, you should be expecting a fault to be present.
- Never sign for anything you have not done.
- If you don't inspect a certain area or component because you 've never
found anything wrong before, don't sign to say that you have inspected it.

Fig 89 - Complacency

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LACK OF KNOWLEDGE
Lack of knowledge can lead to disastrous outcomes in aviation maintenance. If
unsure, always seek information from approved sources like manuals or technical
services. Ignoring this need for information is unacceptable. It’s essential to halt
work until the necessary knowledge is acquired, which might involve consulting
experienced technicians or manufacturer's representatives. Following approved
procedures and using up-to-date data is critical to ensure safety. Delaying a task to
get proper guidance is preferable to risking an error.

SAFETY NETS
- If your knowledge of a particular aircraft or task is lacking, then get that
knowledge.
- Get trained on the type of aircraft or system you are dealing with.
- Use up to date manuals and read them before doing any task.
- If there is something you don't understand then ask a more experienced
engineer for help.

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 Fig 90 - Lack of Knowledge

DISTRACTION
Distractions can significantly impair performance, especially in aviation
maintenance. Frequent interruptions, whether from unplanned changes, phone
calls, or casual conversations, disrupt workflow and can lead to mistakes and
frustration. To mitigate the impact of distractions, it's essential to plan work areas to
minimize casual interruptions and control access to critical zones. If interrupted,
return to the last known step before proceeding to ensure no steps were missed.
Awareness of how disruptions affect others and careful planning can help maintain
focus and safety.

SAFETY NETS:
- If you do get distracted in any way, try to finish the job you are doing at the
time before dealing with the distraction
- This is not always possible, so in that case mark the uncompleted work so
that when you return you will know where you need to start from.
- Fit locking devices as you go, don't leave all the wire-locking to the end of
the job, as it is more likely for one item to be forgotten.
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- Make sure everything you do is double checked by yourself or someone
else to ensure that nothing has been missed.
- Use a detailed worksheet and sign up as you complete each task. When
you return to the job, refer to the work sheet and go back three steps so that
you can be confident that nothing has been missed.

Fig 91 - Distractions

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LACK OF TEAMWORK
Lack of teamwork in aviation maintenance can compromise safety and efficiency.
Experienced engineers may resist collaborative efforts, relying on their individual
judgment rather than embracing the collective expertise of a team. Effective
teamwork involves integrating various skill levels, with the team leader ensuring
discipline and motivation. When teamwork is strong, it enhances performance,
reliability, and safety, as team members support and check each other's work.
Conversely, poor teamwork leads to lower motivation, reduced safety, and
diminished performance.

SAFETY NETS:
- Before a shift starts, discuss what needs to be done and allocate the tasks
fairly. Ensure that everyone understands what they are doing and agrees
with it.
- If two of the shifts want to swap their assigned tasks with each other, let
them (providing there are no other reasons for making the initial job
allocation that they may not be aware of).
- It can be good to try 'team bonding' exercises, whether it is formally or
informally. Team social gatherings help to create a better team-working
environment, for instance.

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 Fig 92 - Lack of teamwork

FATIGUE
Fatigue, often underestimated, significantly contributes to accidents in aviation
maintenance. It results from factors such as lack of sleep, poor nutrition, and
physical exertion. Fatigue impairs performance, especially during night shifts when
circadian rhythms and alertness are low. It disrupts mental and physical states,
affecting variables like body temperature and attention. Shift work exacerbates
fatigue by requiring work during natural low cycles of alertness, making recovery
and effective performance challenging. Recognizing and addressing fatigue is
crucial for preventing maintenance errors and ensuring safety.

SAFETY NETS:
- Be aware of the symptoms of fatigue and look for them in yourself and
others.
- Plan to avoid complex tasks at the bottom of your circadian rhythm. This is
the time to be doing the simple tasks.

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 - Make sure that you sleep and exercise regularly. Remember, the exercise
does not have to be too strenuous
- any form of exercise that increases the heart rate is good for you.

Fig 93 - Fatigue

LACK OF RESOURCES
Lack of resources in aviation maintenance, driven by commercial pressures, can
lead to compromised safety and performance. Cutting corners may involve
reducing staff numbers, which increases overwork and fatigue, or keeping wages

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low, resulting in low morale and high turnover. Insufficient spare parts, tools, or
technical documentation can lead to mistakes and inefficiencies. Proper
resources—staff, parts, tools, and documentation—are crucial for performing
maintenance tasks accurately and efficiently. Ensuring that these resources are
available and used effectively helps maintain aircraft safety and operational
efficiency, ultimately saving time and money.

SAFETY NETS:
- When an aircraft comes into the hangar for an inspection, check suspect
areas for any obvious defects before the inspection starts. This will enable
you to order stocks before they are required.
- Ensure that there is always an adequate stock of spares that are required
on a regular basis.
- If there is another operator of the same aircraft as you at your location,
arrange to pool resources and have the facility to loan spares and
equipment.
- Do not compromise your standards by fitting unserviceable equipment or
used consumables just to get the aircraft out on time. If in doubt, ground the
aircraft.

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 Fig 94 - Lack of resources

PRESSURE
Time pressures in aviation maintenance can lead to errors, particularly when
deadlines are unrealistic. When individuals are pushed to complete tasks quickly,
they might overlook or ignore mistakes to meet deadlines. Proper staffing and
planning are essential to manage workloads and deadlines effectively. Additionally,
external pressures from regulators or manufacturers can impact safety. An
inexperienced engineer should communicate concerns to management rather than
proceeding with tasks they feel unqualified to handle, to prevent potential errors
and ensure safety.

SAFETY NETS:
- Examine the pressure you are under to make sure that it is not self-induced.
- Communicate your concerns with your supervisor. He may be able to
remove some of the pressure you are under.
- Ask for extra help. There may be other engineers working in a different part
of the hangar or other workshop who may be able to assist you.
- If the pressure is getting too much, just say no.

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Fig 95 - Pressure

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LACK OF ASSERTIVENESS
Lack of assertiveness can lead to significant problems in aviation maintenance.
When individuals are not confident in their skills or position, they may be pressured
into accepting or certifying work they doubt. This can result in errors going
unaddressed, as they might avoid admitting problems or feel unable to challenge
incorrect practices. Assertiveness is crucial for ensuring tasks are performed
correctly and preventing overload, as unassertive individuals may overextend
themselves, leading to mistakes and potential accidents. Effective assertiveness
involves confidently communicating one’s knowledge and concerns without
aggression, ensuring safety and quality in maintenance tasks.

SAFETY NETS:
- Be strong. You are a highly trained and skilled engineer with high standards.
Refuse to let anybody force you to compromise those standards
- You cannot be forced to sign a release for an aircraft or component if it is
not serviceable. Just say no.

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 Fig 96 - Lack of assertiveness

STRESS
Stress in aviation maintenance arises from tight deadlines, constant technological
updates, confined workspaces, resource shortages, and the critical nature of the
work. Stressors are categorized as physical, psychological, and physiological. The
impact of stress varies among individuals but can affect psychological and physical
health, job performance, and overall well-being. Stress may lead to errors that go
unnoticed until they result in incidents. Engineers should not certify work if under
stress, and companies must ensure a supportive work environment to prevent
chronic stress and associated risks.

SAFETY NETS:
- Be aware of the symptoms of stress and how it can affect your performance.
- If you are stressed, stop and look rationally at what is causing the stress and
look for ways of reducing it.
- Remember, the amount of stress you experience depends on the demand
that you PERCEIVE is being placed on you and your PERCEIVED ability.
- Take the time to have a break from what you are doing. Have a cup of
coffee or go for a walk - anything to help you relax.
- Don't bottle up your stress - talk about it with your family, friends, work
colleagues or a professional counsellor.

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 Fig 97 - Stress

LACK OF AWARENESS
Lack of awareness in aviation maintenance occurs when technicians become
complacent after repeated tasks, leading to a diminished focus on their
surroundings and actions. This issue can stem from inadequate information,
insufficient knowledge, or poor communication within the organization. Even
experienced personnel can struggle if communication breakdowns result in missing
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or outdated information. It's crucial for every maintenance task to be approached
with the same vigilance as if it were being performed for the first time, and
organizations must ensure effective communication and up-to-date documentation
to maintain awareness and prevent errors.

SAFETY NETS:
- Before doing anything, take the time to think about what could happen in
every eventuality - no matter how unlikely the scenario.
- Check to make sure what you are doing will not conflict with an existing
modification or repair.
- Ask others to check if they can see any potential problems that you may
have missed.

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 Fig 98 - Lack of Awareness

NORMS
In organizations, norms—standard practices or behaviors—can be positive
(following proper procedures) or negative (shortcuts that lead to dangerous
practices). Experienced engineers may develop shortcuts due to time constraints
or manpower shortages, and if these shortcuts become widespread, they can
become ingrained in the company culture. Negative norms are passed on to new
engineers, who may not recognize the risks. This problem is compounded by
failing to consult manuals and service bulletins. Management might overlook
shortcuts for efficiency, but this can lead to serious incidents, such as the 1979
DC10 crash at O'Hare Airport caused by incorrect engine installation methods.

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 Fig 99 - Norms

SAFETY NETS:
- ALWAYS read the maintenance manual before carrying out any servicing
task.
- Work to the instructions it contains and nothing else. If you can think of a
better way to carry out the task, suggest an amendment.
- Do not be temp ted to use an engineers' 'Little Black Book'.

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 - It doesn't matter how long a non-standard practice has been used in your
hangar with no problems - there is only one right way to do a job and that is
the maintenance manual way.

SAFETY NETS
With all the above 'dirty dozen' there are safety nets we can follow to mitigate,
minimize or to prevent dirty dozen leading to errors.

RISK MITIGATION METHODS

Risk mitigation involves planning and developing strategies to reduce threats to
project objectives. It includes identifying, monitoring, and evaluating risks, as well
as implementing actions to address and manage issues and their effects. This
process is a component of the Safety Management System (SMS).

Fig 100 - Risk mitigation approaches

ASSUME AND ACCEPT RISK

The acceptance strategy involves collaborating to identify and understand the risks
and their consequences associated with a project. Team members assess whether
these risks and vulnerabilities are acceptable. This approach ensures that all
involved have a shared understanding of potential risks and their impacts. For
example, when adding a new aircraft type to a Part-145 maintenance organization,
management must be aware of risks such as the potential lack of licensed
personnel before implementation.

Fig 101 - Dealing with the high noise risk

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AVOIDANCE OF RISK
The avoidance strategy involves identifying accepted risks and then taking steps to
avoid them. For example, to address the risk of insufficient human resources when
introducing a new aircraft type, personnel can be sent for type rating courses in
advance of the new type endorsement application. This proactive approach helps
prevent potential issues by ensuring that staff are properly trained before the new
type is officially implemented.

TRANSFERENCE OF RISK
The transference strategy involves shifting the risk and its consequences to
another party. For example, when adding a new aircraft type to the approval, an
organization might contract a HR agency to supply trained personnel. By doing so,
the responsibility for providing qualified staff is transferred to the agency, thus
mitigating the risk of insufficient skilled personnel. This approach must be agreed
upon by all parties involved to be effective.

CONTROLLING RISK
The controlling risk strategy involves taking proactive steps to reduce or eliminate
the impact of identified risks. For instance, to address the risk of not having enough
licensed engineers for a new aircraft type, a company could:

- Send several engineers to type rating courses in advance to ensure they are
trained.
- Contract an HR agency to provide additional trained personnel as needed.

This dual approach helps manage the risk by ensuring both internal and external
resources are available.

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