human factor off01

Human Factors for Aircraft MaintenanceCompiled by Shahzad Khalil

Aug20071

Contents of Course1. General2. Human Performance and Limitations 3. Social Psychology4. Factors affecting Performance5. Physical Environment6. Tasks7. Communication8. Human Error9. Hazards in the Work Place

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Foreword

This course will benefit you both:

professionally – at workplace&

personally – in daily life

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Goal

Awareness of personal behaviour

Minimise errors Reduce the number of incidents Improve Safety – of personnel & aircraft.

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Quotation: To err is human.

Quiz Do human make mistakes? Are we human? Will we make mistakes? Would we like to reduce the possibility of

mistakes?

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Introduction Aviation: Safest forms of

travelling. Chain of Events/human

errors

Solution / Safety Net: If we break the chain at our

level, the accidents will not happen.

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The need to consider the human factor

Most important human factor: Ability to learn from experience & mistakes

committed by others.

Basic Rules:If it has gone wrong once, it will probably go wrong again.

Safety Net:At Design stage – By manufacturer. ( e.g. Cross wires)At user level – By following written procedures.

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Error in aircraft maintenance

Valujet Flight 597: 5 pax & 2 flight attendants injured. 7th Stage high compressor disk failed.

Investigated Causes: Fatigue crack. Poor Record-keeping.

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Reasons of Safety Improvement

better aircraft better air traffic control better weather forecasts.

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It is difficult to fix a faulty person than to fix a faulty component.

Do you agree?

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Human Error Estimates:

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Error Iceburg: A chain of minor events caused accidents. Heinrich Ratio:

Fatal Accidents 1 Non Fatal 10 Reportable accidents 30 Unsafe Acts (Not reported 600

Safety Net: Look below the surface for minor mistakes and

never leave anything unreported.

Saying :Take care of your hours and days, months and years will take care themselves.

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In aviation, Extremely Low Tolerance for Errors

Although we learn through mistakes, yet cannot afford to commit mistakes ourselves and learn. We have to: learn from the mistakes of others.

Proactive Approach:Taking measures, in advance, to avoid the occurrence of any event.

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Causes & Casts of Air Accidents ex: Boeing

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A Simple Mistake by one Person affects an Entire OrgansiationB767 was being brought into Hanger, collided with workstands. Resulting Damage:The following equipment was damaged:

Left-hand horizontal stabilizer Rudder Rear dock stands Hangar wall

Cost factors: The following cost factors resulted from this one mistake: Material Regular and overtime labour Repairs to dock stands and hangar wall Loss of bay facility during additional repair Delayed or third party maintenance for other aircraft Operational complications due to aircraft unavailability Investigation and corrective action

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Cost of one Night Stop at Foreign Station

Approximately 40,000/- USD

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Top seven causes of inflight shutdowns :Boeing analyzed the most common errors behind B767 inflight shutdowns; almost 70% were caused by installation problems.

Incomplete installation (33%) Damage on installation (14.5%) Improper installation (11 %) Equipment not installed or missing (11%) Foreign object damage (6.5%) Improper troubleshooting, inspection, test (6%) Equipment not activated or deactivated (4%)

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Top eight common maintenance errors

Incorrect installation of components Fitting of wrong parts Wrong electrical wiring of parts (including cross

connections) Loose objects left in the aircraft Not enough lubrication Cowling and/or access panels not secured Fuel/oil caps and/or refuel panel not secured Landing gear ground lock pins not removed before

departure

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Who is right? Both are right from their

own positions. When you decide

anything or assign any task to someone, place yourself on his position and see the things as he perceives.

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Aloha Airline’s flight of B737had 18 feet (5.5m) of fuselage skin ripped off.

An AD called for close inspection of 1300 rivets. The inspector had 22 years of experience. The chief inspector had 33 years of experience. In the inspection prior to the incident no cracks were found. A post incident inspection revealed that there were at least 240 cracks

present at the last inspection prior to the incident.

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Comparison of Human Errors to Machine Errors

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Murphy’s Law:

“Anything that can go wrong will go wrong.”

Manufacturers – design changes-make it impossibility to use in

wrong way. e.g. computer connectors. Procedures misunderstood

–Users – improve procedures e.g. Dual inspection.

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Types of Errors

Active error - immediate effect Height of aircraft not read correctly – crash – immediate

effect Latent error - delayed effect

Bolt was corroded – not seen so not replaced will ultimately break.

Delay between the mistake and consequence. e.g. Smoking.

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Conclusions from brief introduction of human Errors

Errors affect both lives and profit. Many errors are made, but it usually requires a chain of

events for a serious incident to occur. Although only a few errors will be the cause of an

accident, it is impossible to predict which one this will be. AMTs must be aware of the different kinds of mistake

they make and the possible consequences. AMTs must know the company's procedures for avoiding

errors and the benefit of following those procedures.

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9.2 HUMAN PERFORMANCE AND LIMITATIONS

Brain – the CPU of Human body. Input devices of human body and their related

senses. Five senses: : smell, taste, sight, hearing

and touch. Minimum level of stimulation – Threshold

values. Health of our senses. Potections.

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Brain Left half of brain thinks

rationally. Used while dealing with problems.

Right half of brain thinks emotionally. Related to creativity and clever ideas.

Which one is correct to use? Both should be used.

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Strategies

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Information Awareness

Five senses - the sources of information. Smell can warn us of dangers. Sense of temperature through touch. Extreme of touch is pain. – sense of touch. Taste – very rarely used. The two most used senses: Sight and

hearing.

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Detection & Awareness Sight sense – eyes. Minimum level of

stimulation / threshold level with naked eye : 60 micron.

Inspection involves: search and decision making.

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Use of eyes: Inspections: 80% of inspections are visual inspection Written documents: Different manuals. Job-cards Writing what you have done. Written Communication:

Legible Accurate Complete Order of sentences.

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Hearing Use ears. AF : 20 Hz – 20 KHz Volume / Audio level in decibel

(dB) Awareness threshold: 0 dB Deteriorate with age and also

suffers from non-reversible permanent damage when exposed to high level of noise.

50% to 80% waking time spent in listening.

Two ears and one tongue.

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Ear Protections

When sound volume > 90 dB Even at 85 dB if remain exposed for

> 4 hours. Earmuffs / Earplugs. Treatment of ears take years.

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What is the difference between Hearing & Listening

Hearing is just the process of taking in sounds. not selective. Passive. Sound of fan, air-conditioner etc.

Listening hearing with selective attention. Involves interpreting the sounds. Active. To each other.

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Listening Interest in topic. Distraction tolerance Appropriate time & place. Listening instead of talking: two ears & one tongue. Preparation Eye contact What is said and what is not said? Sometimes more

information in what is not said. Prejudices : decision already made.

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Hearing Damage

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Different Ways of Information Transfer:

Person to Person: Via verbal communication Via written communication

Display / Product to person: Job cards Manuals Displays Indicators

Person to Product: Key board of computer Controls in aircraft

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Information That is Hard to See or Hear

Noisy environment Makes it hard to hear what people say.

Poor lighting Can't see cracks, loose tools or parts.

Poor communication Not speaking clearly Bad handwriting

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Information Present but Missed

Awareness Problem Completely focused on one task and miss

other things around. Distractions: e.g. During walk-around, a hole

on ground is a distractor. Conversations Interruptions

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Attention and Awareness Selective Attention:

Monitoring several sources of information to decide whether particular event has occurred e.g. deviant reading on several indicators in cockpit.

Focused Attention: Being task focused. Concentrating to one source. e.g. Mechanic reading in noisy environment.

Divided Attention Sustained Attention

Security Guards viewing a TV monitor.

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Mental limits: Disassembly and Re-assembly

There is only one way to disassemble the nuts, but there are 40, 000 wrong ways to re-assemble them.

Knowledge and experience will help to prevent mistakes, but nobody can know everything (Human limitations)

Use of Written instructions and Experience of colleagues can compensate for these limitations.

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Claustrophobia and Physical Access

Claustrophobia: Definition: An irrational fear of being in a

confined or enclosed space. e.g. Maintenance in Fuel Tank. Use Life-Line

Space Availability: More space improves performance.

Controllability: Minimum restrictions due to clothes & shoes.

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9.3 Social Psychology

The area of psychology that deal with how groups behave and how individuals are affected by the group.

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Different Ways to Learn & %age Remembered:

Hear 25% See 30-35% See & Hear 50% Say & Repeat 75% Do 90%

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Motivation

Willingness to put effort into achieving a goal.

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Alfred Adler’s Motivation Theory All human behaviour is goal-directed.

When given the chance to contribute, they become productive, task-oriented employees and in result feel significant.

People are creative decision-makers. An active role in solving problems and decision making.

Humanity is socially embedded. Problems cannot be solved by one person in isolation.

They are solved by co-operation and contribution. Use is more important than possession.

A person's knowledge and skills are of no value if they are not used.

People (and organisations) function holistically. The whole is greater than the sum of the individual parts. A group effort be encouraged.

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Maslow’s Theory of Hierarchy of Needs

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Culture Issues Corporate Culture:

Develop a desirable corporate culture. Pleasant workplace and effective maintenance.

Philosophy: Mission Statement: Clearly worded and communicated.

Guidelines stating what is and is not acceptable. Ceremonies for appropriate recognition. Hearfelt concerns for employees. Open communication.

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Teamwork Planning, co-ordination and communication. Team: a group of inter-dependent individuals

working together to complete a specific task.

Example: Football Team In maintenance, working as a team improves

productivity and reduces injury and equipment damage.

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Characteristics of an Effective Team

1. A clear purpose: accepted by all members. 2. Relaxed: no tensions among the members. 3. Participation: in decisions making and/or activities. 4. Listening: listens to the others. 5. Disagreement: Agree to disagree with each other. 6. Openness: full and open communication. 7. Clear expectations: about the roles each member &

assignments fairly distributed 8. Shared leadership: Delegation of Power. 9. Relations with others: With other teams.10. Team maintenance: focus on their primary goal but also spend

time recognising and maintaining the functions of the team.

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Leadership

The ability to direct and co-ordinate the activities of group members and stimulate / inspire them to work together to complete a specific task.

Lead by example.

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Responsibilities of Leaders

Direct and co-ordinate team activity Delegate tasks to appropriate team members Make sure team members know what is expected of

them Focus attention on important aspects of the situation Adapt to internal and external changes to the

environment Keep team members up to date on work-related

information Ask team members for work-relevant information Provide feedback to team on performance Create and maintain a professional atmosphere

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Effective Leader

Make suggestions Encourage the team to perform Lead by inspiration Provide feedback

How well you lead depends on how well you communicate.

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Types of Leaders Authoritative Leader:

Runs the show alone. Sole decision maker. Controls all the resources. Dictates actions with little input from team members.

Participatory Leader: Encourages participation. Distributes resources and delegate power. Get maximum input from members Group decisions.

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Which type of leadership is better?

Balance between the two types.

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When to use Authoritative and when Participatory?

Authoritative Participatory

Done quickly. Time available.

Task structured. Clear Answers.

Task unstructured. Inputs required.

Conflicts Work well together.

Accepts decision taken by single person.

Do not accepts decision taken by single person.

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9.4. Factors Affecting Performance

Stress Definition:

Physical or psychological tension caused by dealing with difficult situations.

Stressors Personal problems. Work related problem. Social problems.

Cost of Stress Poor work quality – Public safety jeopardised. Heart diseases – Sleeping problem

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Stress and performance Stress in itself is not

necessarily bad. Positive level of stress:

Best Performance. Negative level of stress:

Poor performance.

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Time Pressures & Deadlines

Time pressure sets the pace of work. Stressful Situations:

Overload Under-load

Fire Fighters: Under-loaded & Overloaded

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Varying the Task

Alternate / swap tasks: Physical demanding with mentally demanding High awareness with low awareness Long duration with short duration

Frequent Breaks Break can be a change of work.

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Components of Situation Awareness

Be aware of your surroundings. Use all the senses.

“ Fire , Fire, Fire” Perceiving : e.g. listening of some sound. Comprehending: What that sound mean? Projecting: Thinking about possible consequences.

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Models

Are in diagram form. Drawn to understand complex systems. For example: model of braking system of bicycle to

understand aircraft braking system. Block Diagrams, wiring diagrams etc.

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Why we draw models?

To identify the components of the system. To develop the strategies to improve the

system.

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SHELL Model

Software

Hardware Environment

Liveware (Individual)

Liveware (Group)

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9.7 Communication

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Definitions of Communication

Skill of passing information from on person to another.

Transfer of information from one place to another.

The dynamic and irreversible process by which we make contact and interpret messages within a given situation or context.

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The Transactional Analysis Model

Is an attempt to explain human behavior, especially communication.

Three minds or ego states.

No good or bad ego state.

A healthy personality includes all three.

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The Transactional Analysis Model (Contd.)

Parent: Orders Claims to know everything Caring, encouraging,

supportive & protective. Sentences:

Let me help you. Leave it to me, I will do

this.

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The Transactional Analysis Model (Contd.)

Adult: Asks for reasons. Talk on equal level. Sentences:

What is your opinion? I do not agree.

Child: Emotional Free & natural. Obey, retreat, be polite. Not sure of itself. Sentences:

I do not like you. I do not know, I want

leave.

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Dupont Model Emotional Minds:

Responds faster. Decisions made without

analysis. Sentences:

Hurry up. Forget it.

Rational Minds: Takes more time to react. Decisions made through

analysis.

Balance

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Results of poor communication

Errors Inefficiencies Duplication of effort. Conflict Reduced quality Cost increases

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Results of good communication Reach an understanding with one another. Co-ordinate their efforts. Agree who does what. Decide on actions and make decisions

effectively. Take correct action to reach their goals.

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Forms of communication Verbal communication

the spoken word. face-to-face or through an electronic medium such as a

telephone, radio, loud speaker etc. Non-verbal communication

as body language. Wave, smile or frown.

Written communication Manuals, Job-cards, letters, magazines, books, forms,

e-mail etc.

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Communication model

Communication in its simplest form involves two people: The Sender : the speaker or writer who is transmitting

a message. The Receiver : the person who sees, hears or reads

the message. Feedback Messages filtered through feelings, opinions and

intentions. The message includes body language.

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Three Cs of Communication

Be correct Standard part names.

Be complete. Enough information.

Be clear Say what you mean to say.

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The impact of information technology

e-mail, voice mail, fax machines, mobile phones and pagers. Information technology (IT) improves communication in

organisations in the following ways: It cuts across time boundaries. It cuts across geographical boundaries. It allows multiple, simultaneous reception. Bottlenecks can be avoided as electronic information channels

are typically direct between sender and receiver. It helps reduce paperwork.

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9.8 Human Errors General Model of Human Error:

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Types of Errors

Example: John drives into water and the car begins to hydroplane.

Slip - having a good plan, but bad execution: John's plan is to pump his brakes, but he misses the brake pedal and steps on the accelerator instead.

Mistake - a bad plan is selected: John thinks that speeding up will give him control over his car so he accelerates.

Violation - the wrong procedure is performed intentionally: John learned from his driving teacher that he should pump his brakes in this situation, but his brother said that acceleration is best, so John steps on the accelerator.

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Dirty Dozen

Aviation safety specialist, Gordon Dupont, identified 12 most common human factor maintenance errors, known as dirty dozen that limit people’s ability to perform effectively and safely

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Dirty Dozen ( continued) Lack of communication Lack of teamwork Lack of assertiveness (not enough confidence). Complacency (too relaxed) Distraction Pressure Lack of resources Lack of knowledge Lack of awareness Norms Stress Fatigue

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1. Lack of Communication Communication by:

the spoken words the written words gestures and facial

expressions body language

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Sender-Receiver Model of Communication

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Compare two Log-book Entries

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2. Lack of Team Work

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3. Lack of Assertiveness

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4. Complacency (Too relaxed)

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5. Distraction

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6. Pressure

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7. Lack of Resources

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8. Lack of Knowledge

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9. Lack of Awareness

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10. Norms

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11. Stress

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12. Fatigue

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Shift Work

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13-Feb-05

Thank you for your Attention

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