24

www.mcctraining.co.uk

Communication can be:

Verbal/spoken (a single word, phrase or sentence, a grunt)

Written/textual (printed words and/or numbers on paper or on a screen, hand-written notes)

Non-verbal

Graphic (pictures, diagrams, had-drawn sketches) Symbolic (‗thumbs-up‘, wave of the hand, nod of the head)

Body language (facial expressions, a pat on the back, posture.

Communication (or more often a breakdown in communication) is often cited

as a contributor to incidents and accidents.

Lack of communication is characterised by the engineer who forgets to pass

on pertinent information to a colleague, or when a written message is mislaid.

Poor communication is typified by the engineer who does not make it clear

what he needs to know and consequently receives inappropriate information, or

a written report in barely legible handwriting.

Both problems can lead to subsequent human error.

Good Communication

Think about what you want to say before speaking or writing

Speak or write clearly

Listen or read carefully

Seek clarification wherever necessary.

“The transmission of something from one location to another. The „thing‟

that is transmitted may be a message, a signal, a meaning etc. In order to

have communication, both the transmitter and the receiver must share a

common code, so that the meaning or interpretation contained in the mes-

sage may be interpreted without error”. Penguin Dictionary of Psychology

Dissemination of Information There should normally be someone within an organisation with the responsibil-

ity for disseminating information. Supervisors can play an important role by

ensuring that the engineers within their team have seen and understood any

communicated information.

Poor dissemination of information was judged to have been a contributory

factor to the Eastern Airlines accident in 1983, when the aircraft, en route from

Miami to Nassau in the Bahamas, was forced to return when all three engines

dumped their oil as the result of missing seals.

‗On May 17, 1983, Eastern Airlines issued a revised work card 7204 [master

chip detector installation procedures, including the fitment of O-ring seals]. The

material was posted and all mechanics were expected to comply with the guid-

ance. However, there was no supervisory follow-up to ensure that mechanics

and foremen were incorporating the training material into the work require-

ments. Use of binders and bulletin boards is not an effective means of control-

ling the dissemination of important work procedures, especially when there is

no accountability system in place to enable supervisors to ensure that all me-

chanics had seen the applicable training and procedural information.‘ National Transportation Safety Board accident report

Communication

Martin Coupland

38 Church Meadow

Boverton

Vale of Glamorgan

Wales CF61 2AT

T: +44 (0) 1446 792 382

M: +44 (0) 7796 352 764

martin.coupland@mcctraining.co.uk

The Dirty Dozen “To err is human”. Alexander Pope (1688-1744), poet

Mr Gordon Dupont (Transport Canada) researched numerous aircraft incidents and accidents where Human Factors

had been the primary cause. He concluded that there were essentially 12 factors that were the most common causes

of human error in maintenance—‖The Dirty Dozen‖.

If we could eliminate or control these, we would eliminate a very high percentage of maintenance-related events.

Lack of Communication Discuss work to be done or what has been

completed. Never assume anything. Try to avoid abbreviations without

explaining them.

Complacency Train yourself to expect to find a fault. Never sign for

something you didn't do. Approach repetitive inspections as if for the first

time.

Lack of Knowledge Get type training. Use only the latest editions of

technical documents. Ask a Technical Representative; someone who knows.

Distraction Mark incomplete work. When you return to the job, go back a

couple of steps. Use a detailed check sheet.

Lack of Teamwork Discuss what is to be done, who by and how. Ensure

that everyone understands and agrees.

Fatigue Be aware of the symptoms and look for them in yourself and

others. Avoid complex tasks at the bottom of your circadian rhythm. Sleep

and exercise regularly. Ask others to check your work.

Lack of Resources Order and stock parts well before they are needed.

Remember; manpower is a resource - insufficient personnel puts pressure

on everyone else.

Pressure Ensure pressure isn't self-induced. Communicate your concerns.

Ask for extra help. Just say ―NO".

Lack of Assertiveness Only sign for what is serviceable. Refuse to

compromise your standards.

Stress Be aware of how stress can affect your work. Stop and look ration-

ally at a problem. Work out a rational course of action and follow it. Take

time off or at least a short break. Discuss it with someone. Ask colleagues

to monitor your work. Exercise your body; fight stress.

Lack of Awareness Think what may happen in the event of an accident.

Check to see if your work will conflict with an existing modification or

repair. Ask others if they can see any potential problem with the work done.

Norms Always work in accordance with instructions or have the instruc-

tions changed. Be aware that "we always do it that way" doesn't make it

right.

1

―Human Factors is about people in their work-

ing and living environments, about their rela-

tionship with equipment, procedures and the

environment. Just as importantly, it is about

their relationships with other people. Human

Factors involves the overall performance of

human beings within the aviation system; it

seeks to optimise people‘s performance through

the systematic application of the human scienc-

es, often integrated within the framework of

system engineering. Its twin objectives can be

seen as safety and efficiency.―

International Civil Aviation Organisation (ICAO)

More examples of „Ramp Rash‟ inside.

―The [Part 145] organisation shall establish and

control the competence of personnel involved

in any maintenance, management and/or quality

audits in accordance with a procedure and to a

standard agreed by the competent authority. In

addition to the necessary expertise related to the

job function, competence must include an un-

derstanding of the application of human factors

and human performance issues appropriate to

that person‘s function in the organisation.

‗Human Factors‘ means principles which apply

to aeronautical design, certification, training,

operations and maintenance and which seek

safe interface between the human and other

system components by proper consideration of

human performance. ‗Human performance‘

means human capabilities and limitations which

have an impact on the safety and efficiency of

aeronautical operations.‖ European Aviation Safety Agency Part 145.A.30(e)

Personnel Requirements

―Human factors continuation training should

be of an appropriate duration in each two-year

period in relation to relevant quality audit find-

ings and other internal/external sources of in-

formation available to the organisation on hu-

man errors in maintenance.‖ European Aviation Safety Agency AMC Part 145.A.30(e)

Why have Human Factors training?

A brief history ... In April 1988, an Aloha Airlines Boeing 737-200

suffered a near-catastrophic incident when a large section of the cabin roof separated from the aircraft at 24,000’. Despite this (and one engine failing as it approached touchdown

coupled with a cockpit indication that the nose undercarriage leg was not locked down), the aircraft landed safely, with the loss of only one

life.

Although Human Factors had been an intrinsic part of the aviation world before this point, the authorities found many human factors-related

failings that led up to this incident, and there-fore Human Factors training was treated much more seriously as a result.

mcctraining.co.uk

Issue 2: June 2010

Human Factors

Ramp Rash

It was once estimated that

the annual bill to the airlines

industry worldwide for „ramp

rash‟ (damage to aircraft by

ground contacts) was $1bn.

Recently, doubt was cast on

this figure, so calculations

were re-checked. It was

discovered that the figure

arrived at was inaccurate; in

fact, certain variables had

not been included (lost

revenue due to aircraft

unavailability (not just repair

costs), insurance claims etc).

The true figure is more like

$10bn.

Ramp damage occurs about

once every 1000 flights but

personal injury on the ramp

occurs every 100 flights.

Personal injury costs

account for $4.4bn of the

total figure.

Average aircraft downtime is

3.5 days at an average cost

of $225,000.

Flight International Nov 2005

2

On December 26 2005, a McDonnell

Douglas MD-83, N979AS, operated by

Alaska Airlines, was substantially dam-

aged when the aircraft experienced a rap-

id cabin depressurisation during climb out

from Seattle, Washington.

The airline transport pilot captain and

first officer, the three flight crew mem-

bers and the 137 passengers were unin-

jured.

A new ground baggage handler

(approximately one week on the job),

who was driving a tug towing a train of

baggage carts, said that he waited for a

belt loader to be correctly positioned on

the right side at the middle cargo door of

the aircraft.

He said that he approached the aircraft

from aft to forward, but had to manoeu-

vre around another train of carts to get

close to the belt loader.

Once in position, he said the front of his

tug was 4-5 feet away from the aircraft.

After loading the carts with baggage, he

attempted to drive away. He said that he

turned the tug's wheels as far as possible.

He stated, "I was hoping to make it out,

but I felt my tug going against something.

I immediately set my foot on the brakes

and glanced at the body of the aircraft to

see if there was any damage. It was a

quick glance and I did not see any dam-

age."

He said two other ground personnel came

to assist him in manoeuvring his tug away

from the aircraft. He did not report the

incident to anyone.

The pilot said that the take-off was nor-

mal. During the climb out, at approxi-

mately 26,000 feet, they heard a loud

bang, and the cabin depressurised. He

said that they put their oxygen masks on,

and coordinated a descent to a lower alti-

tude with Seattle Centre. An uneventful

landing was performed at Seattle-Tacoma

International Airport, Seattle, Washing-

ton.

Post landing examination of the fuselage

revealed a 12‖x6‖ hole between the mid-

dle and forward cargo doors on the right

side of the aircraft. After the occurrence,

the ground baggage handler confessed

that he had "grazed the aircraft" with a

tug, while attempting to depart the vicini-

ty of the aircraft.

Alaska Airlines: Cabin Depressurised

CHIRP - Confidential Human Factors Incident Reporting Programme www.chirp.co.uk

Some accidents are difficult to hide.

In the Alaska Airlines MD-83 incident (top of page), the baggage handler obviously

had little idea of how fragile aircraft are and the potentially disastrous consequences of

his ―grazing‖ the fuselage.

The UK Civil Aviation Authority has stressed that it ―seeks to provide an environment

in which errors may be openly investigated in order that the contributing factors and

root causes of maintenance errors can be addressed‖.

―To facilitate this, it is considered that an unpremeditated or inadvertent lapse should not incur any punitive action, but a breach

of professionalism may do so (eg where an engineer causes deliberate harm or damage, has been involved previously in similar

lapses, attempted to hide their lapse or part in a mishap, etc).‖ (Airworthiness Notice 71)

Don’t hide a mistake. You will (probably) keep your job, and others can learn valuable lessons.

Report your mistakes anonymously through CHIRP, the Confidential Human Factors Incident Reporting Programme at www.chirp.co.uk.

23

For more information on stress, visit www.hse.gov.uk/stress

Stress

Stress now accounts for the majority of

lost workdays in the United Kingdom.

Modern lifestyles contribute to stress, and

pressure (both at home and work) raises

stress levels.

Stress is unavoidable (indeed, a certain

amount of stress is beneficial). However,

too much stress can seriously affect your

health.

Recognising that you are becoming over-

stressed and dealing with it are crucial.

What can you do at work?

Talk to your employer: if they don‘t

know there‘s a problem, they can‘t

help. If you don‘t feel able to talk di-

rectly to your employer or manager, ask

an employee representative to raise the

issue on your behalf.

Support your colleagues if they are ex-

periencing work-related stress.

Speak to your doctor if you are worried

about your health.

Discuss with your manager whether it is

possible to alter your job to make it less

stressful for you, recognising your and

your colleagues‘ needs.

Try to channel your energy into solving

the problem rather than just worrying

about it. Think about what would make

you happier at work, and discuss this

with your employer.

What can you do out of work?

Eat healthily.

Stop smoking – it doesn‘t help you to

stay healthy, even though you might

think it relaxes you.

Try to keep within Government recom-

mendations for alcohol consumption –

alcohol acts as depressant and will not

help you tackle the problem.

Watch your caffeine intake – tea, coffee

and some soft drinks (eg cola drinks)

may contribute to making you feel more

anxious.

Be physically active – it stimulates you

and gives you more energy.

Try learning relaxation techniques –

some people find it helps them cope

with pressures in the short term.

Talk to family or friends about what

you‘re feeling – they may be able to

help you and provide the support you

need to raise your concerns at work.

Have a laugh! Laughter releases hor-

mones into your system that combat the

harmful stress hormones.

Health and Safety Executive

Age Related Macular Degeneration http://www.eyesight.nu

ARMD (Aged Related Macular Degener-

ation) is a condition that can normally

affect you as you get older. In fact, alt-

hough it is the leading cause of sight loss

in the over 50s, it is now appearing in

much younger people (some as young as

20 years of age).

It is basically caused by the huge amount

of free radical damage inflicted by sun-

light, wrong foods, toxins and the lack of

nutrients reaching the macula (the small

part of the eye responsible for the

central vision, that allows you to see de-

tail and colours) to protect it from this

free radical damage.

ARMD usually starts in one eye and is

highly likely to affect the other at a later

stage.

The two specific nutrients responsible for

protecting the macula are Lutein and Ze-

axanthin. These Carotenoids are powerful

antioxidants that are known to be missing

in the eyes of sufferers.

Lutein and Zeaxanthin are found in most

fruit and vegetables, and in super quanti-

ties in some vegetables. It is well worth

including these super veggies in your

everyday diet, especially in soups, stir-

fry, oven roast veggies and salads.

This is critical to stop and reverse eye

disease.

Kale 21,900 mcg

Collard Greens 16,300 mcg Spinach - raw 12,600 mcg Spinach - cooked 10,200 mcg Mustard Greens 9,900 mcg

Okra 6,800 mcg Red Pepper 6,800 mcg Romaine Lettuce 5,700 mcg

Endive 4,000 mcg Cooked Broccoli 1,800 mcg Green Peas 1,700 mcg Pumpkin 1,500 mcg

Brussel Sprouts 1,300 mcg Summer Squash 1,200 mcg

Sight-saving treatment currently being

carried out on ARMD sufferers involves

daily injections of a drug called Lucentis

directly into the eyeball. Nice.

Normal Vision

Early ARMD

Advanced ARMD

22

The Control of Noise at Work Regula-

tions 2005 (the Noise Regulations) came

into force for all industry sectors in Great

Britain on 6 April 2006.

The level at which employers must pro-

vide hearing protection and hearing pro-

tection zones (if normal speech cannot be

heard clearly at 1 metre) is now 85

(formerly 90) decibels daily or weekly

average exposure

• and the level at which employers must

assess the risk to workers' health and pro-

vide them with information and training

(if normal speech cannot be heard clearly

at 2 metres) is now 80 (formerly 85) deci-

bels.

“According to the Royal National Institute for Deaf People (RNID), there are about nine million people who are deaf or hard of hearing in the UK. Most of them have lost their hearing gradually with increasing age (presbyacusis). Over half of all people aged over 60 are hard of hearing or deaf.

Hearing loss can also occur at a younger age. There are about 123,000 people over 16 who were born hearing but have devel-oped severe or profound deafness.”

Bupa's health information team, March 2007

CAUSES OF HEARING LOSS

There are many possible causes of hearing loss. These can be divided into two basic types, called conduc-tive and sensorineural hearing loss.

Conductive hearing loss is caused by anything that interferes with the transmission of sound from the outer to the inner ear. Some possible caus-es of conductive hearing loss are:

. Middle ear infections (otitis media).

. Collection of fluid in the middle ear

("glue ear") in children.

. Blockage of the outer ear, most

commonly by wax.

. Otosclerosis, a condition in which

the ossicles of the middle ear harden and become less mobile.

. Damage to the ossicles, for example

by serious infection or head injury.

. Perforated (pierced) eardrum, which

can be caused by an untreated ear infection, head injury or a blow to the ear, or from poking something in your ear.

Sensorineural hearing loss is due

to damage to the pathway that sound impulses take from the hair cells of the inner ear to the auditory nerve and the brain. Some possible causes are:

. Age-related hearing loss

(presbycusis). This is the natural de-cline in hearing that many people ex-perience as they get older. It's partly due to the loss of hair cells in the cochlea.

. Acoustic trauma (injury caused by

loud noise) can damage hair cells.

. Certain viral or bacterial infections

such as mumps or meningitis can lead to loss of hair cells or other dam-age to the auditory nerve.

. Ménière's disease, which causes

dizziness, tinnitus and hearing loss.

. Certain drugs, such as some power-

ful antibiotics, can cause permanent hearing loss. At high doses, aspirin is thought to cause temporary tinnitus - a persistent ringing in the ears. The antimalarial drug quinine can also cause tinnitus, but it's not thought to cause permanent damage.

. Acoustic neuroma. This is a benign

(non-cancerous) tumour affecting the auditory nerve. It needs to be ob-served and is sometimes treated with surgery.

. Other neurological (affecting the

brain or nervous system) conditions such as multiple sclerosis, stroke, or a brain tumour.

Noise and Hearing Protection

Source: http://hcd2.bupa.co.uk/fact_sheets/Mosby_factsheets/Hearing_Loss.html

3

US investigators have determined that

ground staff covered up an accident in

which a vehicle damaged a McDonnell

Douglas DC-9's fuselage, and allowed the

jet to depart for a flight during which it

depressurised.

The Northwest Airlines jet was being

attended in daylight on the ramp at Syra-

cuse, New York, by Air Wisconsin Air-

lines Corporation personnel ahead of op-

erating a flight to Detroit on 18 May last

year.

As the ground crew were dealing with

baggage, the engine of their belt-loader

stopped operating and a senior ground

agent decided to use a luggage tug to

push the loader away from the aircraft.

The tug drove within the safety-clearance

zone - against regulations - and during the

effort to push the loader away, the tug's

cab contacted the fuselage.

In a probable-cause statement on the

event, the National Transportation Safety

Board says: "The senior ground agent

then advised, 'Don't say anything' to one

of the other ground agents who was

working the flight with him."

The extraordinary decision to allow the

DC-9 to depart led the jet to suffer cabin

depressurisation as it climbed through

20,000ft. It performed an emergency de-

scent to 10,000ft and diverted to Buffalo.

Inspection of the aircraft revealed a 12in-

by-5in (30cm-by-13cm) tear in the right

side of the fuselage, about 6ft (1.8m)

ahead of the forward cargo door. There

was also a crease in the skin ahead of the

tear.

Marks on the tear were consistent with

the damage having been caused by the

tug. The jet, 38 years old at the time, had

passed an airworthiness inspection the

day before.

Two weeks after the accident the ramp-

handling company reminded personnel of

safety-zone regulations and underlined

the importance of reporting immediately

any damage to aircraft. It also issued ad-

ditional training materials.

None of the 95 passengers and four crew

members on board the DC-9 was injured

during the depressurisation and diversion.

Flight International, 15/12/2008

CHIRP - Confidential Human Factors Incident Reporting Programme www.chirp.co.uk

DC-9 depressurised after ramp crew covered up tug strike

BA staff arrested after 'failing to report hit-and-run with

baggage truck and passenger jet'

Two British Airways workers are alleged

to have hit a passenger jet with a bag-

gage truck at Heathrow - and then driven

off without telling anyone.

The damage by the electric-powered vehi-

cle, which pulls bags around the airport,

was done to the side of the Airbus A321.

It was only spotted hours later by ground

staff while it waited to taxi to a Terminal

5 runway with 80 people on board. It was

withdrawn from service and the passen-

gers were taken off.

The danger posed by the hit-and-run, and

the fact it was not reported, was consid-

ered so great that police were called in

and the men were arrested and bailed.

The two British Airways staff, one aged

54 and the other 49, with over 40 years

experience between them, have also been

suspended.

A BA insider said, 'For all they knew the

plane could have suffered fuselage dam-

age, causing it to fall apart mid-air.'

The incident happened on Friday morn-

ing. The damage was noticed at around

8.30pm when the jet was due to fly to

Aberdeen. Bosses have ordered an inves-

tigation.

The two workers could face charges of

criminal damage and endangering safety.

A police spokesman said: 'We were called

in by ground staff at Heathrow after they

became aware of fuselage damage.'

The 54-year-old man has been bailed

until a date the end of February and the

younger man until early March, he add-

ed.

A BA spokesman confirmed: 'Two mem-

bers of our ground staff based at

Heathrow were arrested following an

incident where one of our aircraft was

damaged. They were both questioned by

the police and released on bail pending

further inquiries. It would therefore be

inappropriate to give further details.'

Daily Mail 14th January 2009

4

Nov 2, 2004 A Robinson R44 helicopter was being flown from Cork, Ireland, to Weston, Ireland.

About 700 feet above ground-level, severe vibrations of the cyclic control began, and the controls became “stiff and heavy.” The pilot conducted an emergency landing in a field two miles (three kilometers) from Cork Airport. Af-ter exiting the helicopter, the pilot examined the area un-derneath the auxiliary fuel tank and noticed oil on the fire-wall.

The pilot, the only occupant, was not injured, and the heli-copter received minor damage in the incident.

An engineer was called to the scene of the landing to in-vestigate the problem.

“The engineer confirmed by using a hydraulic ground rig that the forced landing was caused by loss of hydraulic fluid in the flight control system, which in turn resulted in the flying controls functioning without hydraulic servo as-sistance,” said the report by the Irish Air Accident Investi-gation Unit.

“The engineer detected that the leak was coming from a T-piece union on the output side of the hydraulic pump.

He removed the union and noted that the O-ring retainer had a ring mark around it, indicating that the associated union nut was tightened too far up the union and distorted the retainer.”

The helicopter manufacturer said that the retainer, which seats the O-ring seal, had not been installed properly dur-ing manufacture, the report said. Because the retainer is not visible after installation, the manufacturer used a leak check with normal system pressure to verify that the in-stallation was correct.

The manufacturer has since revised procedures to pro-vide for visually inspecting the retainers and O-ring seals earlier, to verify correct assembly before the fittings are installed in the final assembly.

At the time of the incident, the helicopter had a total of 24 flight hours since new.

“The incident shows that an improperly installed retainer may not cause a leak for several flying hours,” said the report.

Incorrect Installation Produces Delayed Hydraulic Leak

There is currently no requirement for Human Factors training in manufacturing/operating environments.

21

• Norms

• Simplify task

• Save time/effort

• Break rules for “kicks”

• Unrelated to task

• Satisfy personal need• Time Pressures

• Workload Pressures

• Poor Procedures

• Poor Tooling

• Poor Conditions

Inevitable due

to tasks or

circumstances

Exceptional

Situational

Optimising

Routine

VIOLATIONS

• Norms

• Simplify task

• Save time/effort

• Break rules for “kicks”

• Unrelated to task

• Satisfy personal need• Time Pressures

• Workload Pressures

• Poor Procedures

• Poor Tooling

• Poor Conditions

Inevitable due

to tasks or

circumstances

Exceptional

Situational

Optimising

Routine

VIOLATIONSExceptional

Situational

Optimising

Routine

VIOLATIONS

Violations in Aircraft Maintenance It is an unfortunate fact of life that violations occur in aviation maintenance. Most stem from a genuine desire to do a good job. Seldom are they acts of vandalism or sabotage. However, they represent a significant threat to safety as systems are designed assuming people will follow the procedures. There are four types of violations: R - routine O - optimising S - situational E - exceptional

Routine violations are things which have become ‟the normal way of doing something‟ within the person‟s work group (eg a maintenance team). They can become routine for a number of reasons: engineers may believe that pro-cedures may be over-prescriptive and violate them to simplify a task (cutting corners), to save time and effort. Examples of routine violations are not performing an engine run after a borescope inspection (“it never leaks”), or not changing the O-ring seals on the engine gearbox drive pad after a borescope inspection (“they are never damaged”). Optimising violations involve breaking the rules for ‟kicks‟. These are often quite unrelated to the actual task - the person just uses the opportunity to satisfy a personal need. An example of an optimising violation would be an engi-neer who has to go across the airfield and drives there faster than permitted. Situational violations occur due to the particular factors that exist at the time, such as time pressure, high workload, unworkable procedures, inadequate tooling or poor working conditions. These occur often when, in order to get the job done, engineers consider that a procedure cannot be followed. An example of a situational violation is an incident which occurred where the door of a B747 came open in-flight. An engineer with a tight deadline discovered that he needed a special jig to drill off a new door torque tube. The jig was not available, so the engineer decided to drill the holes by hand on a pillar drill. If he had complied with the maintenance manual he could not have done the job and the aircraft would have missed the service. Exceptional violations are typified by particular tasks or operating circumstances that make violations inevitable, no matter how well-intentioned the engineer might be.

Error Types: Violations

20

Violations

Mistakes

Lapses

Slips

ERROR

TYPES

Actions not as intended(skill-based)

Forgetting something(skill based)

Doing something you believe

was correct (but wasn‟t)(knowledge based)

Deliberate illegal actions(rule based)

Violations

Mistakes

Lapses

Slips

ERROR

TYPESViolations

Mistakes

Lapses

Slips

ERROR

TYPES

Actions not as intended(skill-based)

Forgetting something(skill based)

Doing something you believe

was correct (but wasn‟t)(knowledge based)

Deliberate illegal actions(rule based)

Error Types

Slips can be thought of as actions not carried out as intended or planned, eg transposing dig-its when copying out numbers, or misordering steps in a procedure. They typically occur at the task execution stage.

Lapses are missed actions and omissions, ie when somebody has failed to do some-thing due to lapses of memory and/or at-tention or because they have forgotten something, eg forgetting to replace an en-gine cowling. They occur at the storage (memory) stage. Mistakes are a specific type of error brought

about by a faulty plan/intention, ie somebody did something believing it to be correct when it was, in fact, wrong, eg an error of judgement such as mis-selection of bolts when fitting an aircraft wind-screen. They occur at the planning stage.

Violations sometimes appear to be human errors, but they differ from slips, lapses and mistakes be-cause they are deliberate ‟illegal‟ actions, ie some-body did something knowing it to be against the rules (deliberately failing to follow proper procedures). Aircraft maintenance engineers may consider that a violation is well intentioned, ie ‟cutting corners‟ to get a job done on time. However, procedures must be followed appropriately to help safeguard safety.

Skill-based behaviours are those that rely on stored routines or motor programmes that have been learned with practice and may be executed without conscious thought. Rule-based behaviours are those for which a routine or procedure has been learned. The components of a rule-

based behaviour may comprise a set of discrete skills. Knowledge-based behaviours are those for which no procedure has been established. These require the aircraft maintenance engineer to evaluate information, and then use his knowledge and experience to formulate a plan for dealing with the situation.

5

For more information on this incident, visit http://www.aaib.dft.gov.uk/publications/bulletins

No Torque Figure Specified by Manufacturer

During the cruise, some four minutes into

the flight, the helicopter suffered severe

vibration. The pilot carried out an autoro-

tation and landed safely.

Subsequent investigation revealed that

one of the two tail-rotor trunnion flange

caps had separated, causing damage to a

tail-rotor blade and the vertical fin.

Agusta A109S Grand, G-CGRI 7 April 2006, Liskeard, Cornwall

The metallurgical examination showed

the failure to be due to an initial clock-

wise torsional overload followed by a

final axial tensile overload. It is possible

that the initial clockwise torsional over-

load was applied either during the manu-

facture of the helicopter or during mainte-

nance activity during the night prior to the

incident flight.

The maintenance manual did not contain

the specific torque-loading for the trun-

nion flange caps.

The helicopter manufacturer has since

issued torque loading figures for the

flange caps and has amended the

maintenance manual accordingly.

6

A circadian rhythm is an approximate daily periodicity, a roughly-24-hour cycle in the biochemical, physiological or be-havioural processes of living beings.

Circadian rhythms are important in deter-mining the sleeping and feeding patterns of all animals, including human beings.

There are clear patterns of core body tem-perature, brain wave activity, hormone production, cell regeneration and other biological activities linked to this daily cy-cle.

In addition, photoperiodism, the physio-logical reaction of organisms to the length of day or night, is vital to both plants and animals, and the circadian system plays a role in the measurement and interpreta-tion of day length.

The clock affects our level of alertness over about 24 hours. You can see from the illustration that we are most alert around 9 in the morning and around 7 at night. Our lowest level of alertness is around 2 in the afternoon and even lower between 1 and 3 am.

Even if you are working permanent night-shifts, the clock does not compensate. You will always be at your lowest level of alertness in the early hours.

However, it is also worth noting that your level of alertness mid-afternoon is also low; you will feel tired.

When you are tired, your decision-making will be impaired.

Therefore, you should consider the impli-cations of the Circadian Clock on your work schedule.

1990: BAC 1-11 Windscreen Blowout

Download the report from: http://www.aaib.gov.uk/publications/rmal_reports/1_1992__g_bjrt.cfm

“This is your Captain screaming …”

On 10 June 1990, a BAC 1-11 aircraft

(British Airways Flight 5390) departed

Birmingham International Airport for

Malaga, Spain, with 81 passengers, 4

cabin and 2 flight crew.

The co-pilot was the pilot flying during

the take-off and, once established in the

climb, the pilot-in-command handled the

aircraft in accordance with the operator's

normal operating procedures.

At this stage both pilots released their

shoulder harnesses and the pilot-in-

command loosened his lap-strap. As the

aircraft was climbing through 17,300 feet

pressure altitude, there was a loud bang

and the fuselage filled with condensation

mist indicating that a rapid decompres-

sion had occurred.

A cockpit windscreen had blown out and

the pilot-in-command was partially

sucked out of his windscreen aperture.

The flight deck door blew onto the flight

deck where it lay across the radio and

navigation console.

The co-pilot immediately regained con-

trol of the aircraft and initiated a rapid

descent to FL 110.

The cabin crew tried to pull the pilot-in-

command back into the aircraft but the

effect of the slipstream prevented them

from succeeding. They held him by the

ankles until the aircraft landed.

The investigation revealed that the acci-

dent occurred because a replacement

windscreen had been fitted with the

wrong bolts.

Alertness Levels: The Circadian Clock

19

Peer Pressure In the working environment of aircraft maintenance, there are many pressures brought to bear on the individual en-gineer. There is the possibility that the aircraft mainte-nance engineer will receive pressure at work from those that work with him. This is known as peer pressure.

Peer pressure is the „actual or perceived pressure which an individual may feel, to conform to what he believes that his peers or colleagues expect‟. For example, an individual engineer may feel that there is pressure to cut corners in order to get an aircraft out by a certain time, in the belief that this is what his colleagues would do under similar circumstances. There may be no actual pressure from management to cut corners, but subtle pressure from peers, eg taking the

form of comments such as 'You don't want to bother checking the manual for that. You do it like this...' would constitute peer pressure. Peer pressure thus falls within the area of conformity. Conformity is the tendency to allow one's opinions, atti-tudes, actions and even perceptions to be affected by prevailing opinions, attitudes, actions and perceptions. The influence of peer pressure and conformity on an indi-vidual's views can be reduced considerably if the individu-al airs his views publicly from the outset. However, this can be very difficult. Conformity is closely linked with 'culture'. It is highly rele-vant in the aircraft maintenance environment where it can work for or against a safety culture, depending on the attitudes of the existing staff and their influence over new-comers. In other words, it is important for an organisation to engender a positive approach to safety throughout their workforce, so that peer pressure and conformity per-petuates this. In this instance, peer pressure is clearly a good thing. Too often, however, it works in reverse, with safety stand-ards gradually deteriorating as shift members develop practices which might appear to them to be more effi-cient, but which erode safety. These place pressure, al-beit possibly unwittingly, upon new engineers joining the shift, to do likewise.

There is probably no industry in the commercial environment that does not impose some form of deadline, and consequently time pressure, on its employees. Aircraft maintenance is no exception. One of the potential stressors in maintenance is time pressure. This might be actual pressure, where clearly specified deadlines are im-posed by an external source (eg management or supervisors) and passed on to en-gineers, or perceived, where engineers feel that there are time pressures when car-rying out tasks, even when no definitive deadlines have been set in stone. In addition, time pressure may be self imposed, in which case engineers set them-selves deadlines to complete work (eg completing a task before a break or before the end of a shift). Management have contractual pressures associated with ensuring an aircraft is re-leased to service within the time frame specified by their customers. Striving for higher aircraft utilisation means that more maintenance must be accomplished in fewer hours, with these hours frequently being at night. Failure to do so can impact on flight punctuality and passenger satisfaction. Thus, aircraft maintenance engineers have two driving forces:

the deadlines handed down to them and

their responsibilities to carry out a safe job. The potential conflict between these two driving pressures can cause problems.

Time Pressure

18

Phobias

Although not peculiar to aircraft maintenance engineering, working in restricted space and at heights is a feature of

this trade. Problems associated with physical access are not uncommon. Maintenance engineers and technicians often have to access, and work in

very small spaces (eg in fuel tanks)

cramped conditions (such as beneath flight instrument panels, around rudder pedals)

elevated locations (on cherry-pickers or staging), and

sometimes in uncomfortable climatic or environmental conditions (heat, cold, wind, rain, noise).

This can be aggravated by aspects such as poor lighting or having to wear breathing apparatus.

There are many circumstances where people may experi-ence various levels of physical or psychological discomfort when in an enclosed or small space, which is generally

considered to be quite normal. When this discomfort be-comes extreme, it is known as claustrophobia.

Claustrophobia can be defined as ‘abnormal fear of being in an enclosed space’.

It is quite possible that susceptibility to claustrophobia is

not apparent at the start of employment. It may come

about for the first time because of an incident when working within a confined space, eg panic if unable to extricate oneself from a fuel tank.

If an engineer suffers an attack of claustrophobia, he

should make his colleagues and supervisors aware so that if tasks likely to generate claustrophobia cannot be avoid-ed, at least colleagues may be able to assist in extricating

the engineer from the confined space quickly, and sympa-thetically.

Engineers should work in a team and assist one another if necessary, making allowances for the fact that people come in all shapes and sizes and that it may be easier for

one person to access a space than another. However, this should not be used as an excuse for an engineer who has put on weight, to excuse himself from jobs which he

would previously have been able to do with greater ease!

Acrophobia

Working at significant heights can also be a problem for some aircraft maintenance engineers, especially when doing crown inspections (top of fuselage, etc).

Some engineers may be quite at ease in situations like

these, whereas others may be so uncomfortable that they are far more concerned about the height, and holding on to the access equipment, than they are about the job in

hand. In such situations, it is very important that appro-priate use is made of harnesses and safety ropes. These will not necessarily remove the fear of heights, but will

certainly help to reassure the engineer and allow him to concentrate on the task in hand.

Ultimately, if an engineer finds working high up brings on phobic symptoms (such as severe anxiety and panic), they should avoid such situations for safety's sake. How-

ever, as with claustrophobia, support from team mem-bers can be helpful.

Shortly before the Aloha Airlines accident, during mainte-nance, the inspector needed ropes attached to the rafters of the hangar to prevent falling from the aircraft when it

was necessary to inspect rivet lines on top of the fuse-lage. Although unavoidable, this would not have been

conducive to ensuring that the inspection was carried out meticulously (nor was it, as the subsequent accident in-vestigation revealed).

Managers and supervisors should attempt to make the job as comfortable and secure as reasonably possible (eg

providing knee pad rests, ensuring that staging does not wobble, providing ventilation in enclosed spaces, etc) and allow for frequent breaks if practicable.

7

24 AUG 2001

Airbus A.330-243 C-GITS

Operator: Air Transat

Year Built: 1999

Total Airframe Hrs: 10433 hours

Cycles: 2390 cycles

Engines: 2 Rolls Royce Trent 772B

Crew: 0 fatalities / 13 on board

Passengers: 0 fatalities / 293 on board

Total: 0 fatalities / 306 on board

Aircraft Damage: Substantial

Location: Terceira-Lajes AFB, Azores

Departure: Toronto-Pearson International

Airport, Canada

Destination: Lisboa Airport, Portugal

Flight number: 236

Air Transat Flight TS236, was en route at

FL390 when, at 05:36 UTC, the crew

became aware of a fuel imbalance be-

tween the left and right-wing main fuel

tanks. Five minutes later the crew, con-

cerned about the lower-that-expected fuel

quantity indication, decided to divert to

Lajes Airport in the Azores.

At 05:48 UTC, when the crew ascertained

that a fuel leak could be the reason for the

possible fuel loss, an emergency was de-

clared to Santa Maria Oceanic Control.

At 06:13, at a calculated distance of 135

miles from Lajes, the right engine flamed

out. At 06:26, when the aircraft was about

85 nm from Lajes and at an altitude of

about FL345, the left engine flamed out.

At 06:39 the aircraft was at 13,000 feet

and 8 miles from the threshold of runway

33. An engines-out visual approach was

carried out and the aircraft landed on run-

way 33.

Eight of the plane's ten tyres burst during

the landing. An investigation determined

that a low-pressure fuel line on the right

engine had failed, probably as the result

of its coming into contact with an adja-

cent hydraulic line.

FINDINGS AS TO CAUSES AND CONTRIBUTING FACTORS

. The replacement engine was received in

an unexpected pre-SB configuration to

which the operator had not previously

been exposed.

. Neither the engine-receipt nor the en-

gine-change planning process identified

the differences in configuration between

the engine being removed and the engine

being installed, leaving complete reliance

for detecting the differences upon the

technicians doing the engine change.

. The lead technician relied on verbal

advice during the engine change proce-

dure rather than acquiring access to the

relevant SB, which was necessary to

properly complete the installation of the

post-mod hydraulic pump.

. The installation of the post-mod hy-

draulic pump and the post-mod fuel tube

with the pre-mod hydraulic tube assembly

resulted in a mismatch between the fuel

and hydraulic tubes.

. The mismatched installation of the pre-

mod hydraulic tube and the post-mod fuel

tube resulted in the tubes coming into

contact with each other, which resulted in

the fracture of the fuel tube and the fuel

leak, the initiating event that led to fuel

exhaustion.

. Although the existence of the optional

Rolls-Royce SB RB.211-29-C625 be-

came known during the engine change,

the SB was not reviewed during or fol-

lowing the installation of the hydraulic

pump, which negated a safety defence

that should have prevented the mis-

matched installation.

. Although a clearance between the fuel

tube and hydraulic tube was achieved

during installation by applying some

force, the pressurisation of the hydraulic

line forced the hydraulic tube back to its

natural position and eliminated the clear-

ance.

. The flight crew did not detect that a fuel

problem existed until the Fuel ADV advi-

sory was displayed and the fuel imbal-

ance was noted on the Fuel ECAM page.

. The crew did not correctly evaluate the

situation before taking action.

. The flight crew did not recognise that a

fuel leak situation existed and carried out

the fuel imbalance procedure from

memory, which resulted in the fuel from

the left tanks being fed to the leak in the

right engine.

. Conducting the FUEL IMBALANCE

procedure by memory negated the de-

fence of the Caution note in the FUEL

IMBALANCE checklist that may have

caused the crew to consider timely action-

ing of the FUEL LEAK procedure.

. Although there were a number of other

indications that a significant fuel loss was

occurring, the crew did not conclude that

a fuel leak situation existed - not action-

ing the FUEL LEAK procedure was the

key factor that led to the fuel exhaustion.

For more information on this incident, visit http://www.transat.com/en/media_centre

2001: A New World Record (80-mile glide by an airliner)

crack

chafing

8 out of 12 tyres burst

8

From http://www.flightglobal.com 9 Oct 2008 (sourced from Air Transport Intelligence)

Cathay 747 tractor collision enquiry cites aircrew fatigue

Swedish investigators believe pilot fatigue

contributed to a Cathay Pacific Boeing 747-200 freighter sustaining heavy engine damage after accidentally taxiing into its

tow-tractor at Stockholm Arlanda last year.

The pilots had been awake for 18-20 hours by the time of the accident, which occurred early on 25 June just after the

jet had been pushed back from stand R9 for a service to Dubai.

Investigation commission SHK has con-cluded that, shortly after the tow-tractor was disconnected from the nose-gear, the pilots started to taxi the aircraft before a

ground technician had given an unambig-uous all-clear signal. The Schopf 356 trac-tor had been moved a short distance but

was out of the pilots' field of vision. SHK says that, while the pilots read the

normal checklist after engine start, it "did not contain any point" concerning a 'clear signal' - a specific thumb-up gesture

showing that the aircraft is clear to taxi.

Only a supplemental note in the carrier's expanded checklist informed pilots that the ground dispatcher would "clearly dis-play" to them the steering pin removed

from the nose-gear.

“Abandon ship!” The Arlanda tow-tractor driver, who was preparing to move the vehicle clear, hasti-ly abandoned it when he heard the 747's engines powering up.

Both the driver and the ground technician

"had to run in order to be safe" and the aircraft struck the tractor with its inboard left-hand Rolls-Royce RB211 engine. The

rear of the vehicle penetrated the nacelle by 20-30cm, heavily damaging the cowl-ing, pumps, fuel lines and control units,

and the engine began leaking fuel.

In its report into the accident, which also badly damaged the tractor, SHK states

that - despite the fuel leak, close to hot exhaust and electrical wiring - emergency services were not summoned for nearly

an hour. It attributes the collision to "inadequate"

checklists for the crew regarding confir-mation of an all-clear signal. But SHK also highlights the length of time the pilots

had been awake and says the time of the accident, 03:33, was within a biological window of low activity. Stress and fatigue, it says, probably limited the crew's con-

centration abilities. See the „Circadian Clock‟ on Page 6.

It‘s not the first (or probably last) time

this type of collision has happened (see

the picture on the front page and the arti-

cle on next page).

17

(From an article by Anastasia Stephens, Daily Mail 15 Aug 2009)

The £17 eye test that could save your life Thousands of Britons could be saved from the devastating effects of seri-ous illness such as heart disease, diabetes and brain tumours simply by attending a regular eye test at their local High Street opticians, say ex-perts. Studies have found that as many as one in five of us have a health prob-lem not related to the eye that could be diagnosed through a routine eye test. However, only about 20 per cent of us go for the recommended check-up every two years. A 30-minute examination, which costs as little as £17, can spot the early signs of a range of life-threatening health conditions. Dr Susan Blakeney, fellow of the Col-lege of Optometrists in London, says: 'An eye test is an integral part of a general health check-up. Serious illnesses other than eye disease can be identified, such as signs of diabe-tes, high blood pressure, high choles-terol and even brain tumours.' According to Brain Tumour UK, an estimated 16,000 people are diag-nosed with brain tumours in Britain each year. And up to 30 per cent of these tumours could be spotted through routine eye tests, often at an early stage. 'Brain tumours may cause swelling of the optic nerve, which can appear large and pale,' says Trevor Lawson of Brian Tumour UK. 'There can be loss of vision in certain areas and headaches. If spotted early, such diagnoses can be life-saving, catching the tumour before it spreads or causes perma-nent damage to brain tissue. 'Sadly, in many cases they are picked up too late and in these cases survival rates for malignant brain tu-mours are 14 per cent.' Over-60s, who are more at risk, would benefit from annual check-ups,

but only 47 per cent do so, according to the Royal National Institute of Blind People. Optometrist Carolyn Zweig says: 'Diabetes can cause leakage of blood and fluid at the back of the eye and changes to blood vessels, easily spotted during an eye test.

High blood cholesterol, which leads to coronary heart disease, stroke and heart attack, can cause a white ring to appear around the cornea, the out-er surface of the eye, early on.

Another indicator of heart disease, high blood pressure, can cause burst

blood vessels at the back of the eye, which an optometrist would see.' Complex neurological conditions such as multiple sclerosis, thyroid disease and even cancer can also be revealed during an eye test. 'Multiple sclerosis can cause swelling of the optic nerve which can appear abnormally large and pale,' says Zweig. 'And an overactive thyroid gland, or tumour in the neck, can re-sult in an abnormal bulging of the cornea.'

During an eye test, optometrists check eyesight by asking patients to read letters on a chart. A light is shone on the front of the eyes to check how they react, and a magnify-ing instrument called an ophthalmo-scope is used to check the back of the eyes. The optometrist will also check that the muscles that control eye movement are working well.

16

Vision

Basic Function of the Eye

The basic structure of the eye is simi-lar to a simple camera with an aper-ture (the iris), a lens and a light sen-

sitive surface (the retina). Light enters the eye through the cor-

nea, then passes through the iris and the lens and falls on the retina. Here the light stimulates the light-sensitive

cells on the retina (rods and cones) and these pass small electrical im-pulses by way of the optic nerve to

the visual cortex in the brain. Here, the electrical impulses are interpreted and an image is perceived.

Cornea

The cornea is a clear 'window' at the very front of the eye. The cornea acts as a fixed focusing device. The focus-

ing is achieved by the shape of the cornea bending the incoming light rays. The cornea is responsible for

between 70% and 80% of the total focusing ability (refraction) of the eye.

Iris and Pupil The iris (the coloured part of the eye)

controls the amount of light that is allowed to enter the eye. It does this by varying the size of the pupil (the

dark area in the centre of the iris). The size of the pupil can be changed

very rapidly to cater for changing light levels. The amount of light can be adjusted by a factor of 5:1.

Lens After passing through the pupil, the

light passes through the lens. Its shape is changed by the muscles (cillary muscles) surrounding it which

results in the final focusing adjust-

ment to place a sharp image onto the

retina. The change of shape of the lens is called accommodation. In or-der to focus clearly on a near object,

the lens is thickened. To focus on a distant point, the lens is flattened.

The degree of accommodation can be affected by factors such as fatigue or the ageing process.

When a person is tired, accommoda-tion is reduced, resulting in less sharp

vision (sharpness of vision is known as visual acuity).

The retina is located on the rear wall of the eyeball. It is made up of a complex layer of nerve cells connect-

ed to the optic nerve. Two types of light sensitive cells are found in the retina - rods and cones.

The central area of the retina is known as the fovea and the receptors in this area are all cones. It is here

that the visual image is typically fo-cused. Moving outwards, the cones become less dense and are progres-

sively replaced by rods, so that in the periphery of the retina, there are only

rods. Cones function in good light and are

capable of detecting fine detail and are colour sensitive. This means the human eye can distinguish about

1000 different shades of colour. Rods cannot detect colour. They are

poor at distinguishing fine detail, but

good at detecting movement in the

edge of the visual field (peripheral vision). They are much more sensi-tive at lower light levels. As light de-

creases, the sensing task is passed from the cones to the rods. This

means in poor light levels we see only in black and white and shades of grey.

At the point at which the optic nerve joins the back of the eye, a 'blind

spot' occurs. This is not evident when viewing things with both eyes (binocular vision), since it is not pos-

sible for the image of an object to fall on the blind spots of both eyes at the same time. Even when viewing with

one eye (monocular vision), the con-stant rapid movement of the eye (saccades) means that the image will

not fall on the blind spot all the time. It is only when viewing a stimulus that appears very fleetingly (eg a

light flashing), that the blind spot may result in something not being

seen. In maintenance engineering, tasks

such as close visual inspection or crack detection should not cause such problems, as the eye or eyes move

across and around the area of inter-est (visual scanning).

Optic Nerve

To the brain

9

El Al 747 crushes tow tractor at Paris Charles de Gaulle

From http://www.flightglobal.com 16 Apr 2007

Lack of Communication*

French investigators have started an in-

quiry after an El Al Boeing 747-400 suf-

fered severe engine damage at Paris after

it taxied over its pushback tractor.

The Israeli-operated aircraft was prepar-

ing to depart Paris Charles de Gaulle for

Tel Aviv during late morning on 13 April

when the incident occurred. It crushed the

tow tractor under the number three en-

gine, heavily damaging both.

A spokesman for airports operator Aero-

ports de Paris says the pushback tractor

had been disconnected from the aircraft

but was still under the 747 when it started

to taxi.

―During the departure the tractor had

pushed back the aircraft,‖ he says. ―It was

still under the aircraft and the pilot decid-

ed to go without authorisation from the

ground staff. Normally the pilot has to

wait for ground staff authorisation before

moving.‖

The aircraft involved was the youngest

747-400 in El Al‘s fleet, an eight-year old

example registered 4X-ELD.

All of El Al‘s 747-400s are equipped with

Pratt & Whitney PW4056 powerplants.

None of the occupants on board the jet,

including 374 passengers, was injured.

*See back page—The Dirty Dozen.

More ramp rash ...

Madrid, 8 Jan 2004

McDonnell Douglas MD-82 hit by a

tractor in the second forward hold

door (no further information availa-

ble).

10

July 2008: Three planes collide in Baton Rouge

Edited version of the report at: http://www.wafb.com

Three CRJ passenger jets sustained serious damage when a young mechanic pressed a starter switch to slowly spin jet en-gine compressor blades for routine washing.

She had successfully performed the same action on the jet's right engine without difficulty. However, mechanics familiar with the accident said that when the mechanic repeated the action on the left engine of the CRJ model 700 jet, a computer control system known as "FADEC" ignited the engine and immediately spun up to near take-off power. Someone had left the throttle setting for the left engine at 85% power, sources said.

The 34 ton passenger jet leapt forward, ploughing into two other CRJ aircraft in the hangar. Airport manager Anthony Marino said the pair of model 200 aircraft that were damaged will be repaired at the Baton Rouge maintenance facility, which employs 120 people. "That's a sign of the high skill levels over there" at the new ASA hangar. Ma-rino was instrumental in construction of the $6 million hangar to lure the ASA maintenance facility to Baton Rouge.

Marino acknowledged that the three-plane smash-up could have become an explosive disaster. The incident occurred in the pre-dawn hours of Monday, July 7th. None of the 14 ASA mechanics and cleaning workers inside the hangar was injured. ASA spokeswoman Modolo said the investigation of the acci-dent is still underway. Ordinarily, any damage that renders an aircraft not flyable requires a report to the National Transporta-tion Safety Board. However, the NTSB told WAFB News it was not investigating the ASA incident. The aircraft carried no pas-sengers, were not in flight, and were damaged in an FAA-approved maintenance facility. Together, the three jets are valued at $50 million, according to Modolo. The young woman who set the multi-million dollar chain of events in motion is not likely to bear full blame for the event. "There's plenty of blame to go around," said one airport employ-ee familiar with the accident.

CRJ 700 CRJ 200

15

Memory

IMPROVING THE MEMORY

The best way to improve memory seems to be to increase the supply of oxygen to the brain, which may be accomplished with aerobic exercises; walking for three hours each week suffices, as does swimming or bicycle riding. One study found that chewing gum will supply the brain with enough oxy-gen to help memorise items simply because of the muscle movement.

It‟s thought that the process of writing a working memory into the long-term memory store is largely controlled by a seahorse-shaped set of neurons in the brain called the hippocampus.

TYPES OF MEMORY

A basic and generally accepted clas-sification of memory is based on the duration of memory retention, and identifies 3 distinct types of memory:

sensory memory

short-term memory

long-term memory.

Sensory Memory The ability to look at an item, and re-member what it looked like with just a second of observation, or memorisa-tion, is an example of sensory memory. With very short presentations, partici-pants often report that they seem to "see" more than they can actually report.

Short-Term Memory Short-term memory allows one to re-call something from several seconds to as long as a minute without re-hearsal. Its capacity is also very limited: exper-iments have shown that the store of short term memory was 7±2 items. Memory capacity can be increased through a process called chunking. For example, if presented with the string:

FBIPHDTWAIBM

people are able to remember only a few items. However, if the same infor-mation is presented in the following way:

FBI PHD TWA IBM people can remember a great deal more letters. This is because they are able to chunk the information into meaningful groups of letters. The ideal size for chunking letters and numbers is three.

Long-Term Memory

The storage in sensory memory and short-term memory generally have a strictly limited capacity and duration, which means that information is avail-able for a certain period of time, but is not retained indefinitely. By contrast, long-term memory can store much

larger quantities of information for potentially unlimited duration (sometimes a whole life span). For example, given a random seven-digit number, we may remember it for only a few seconds before forgetting, suggesting it was stored in our short-term memory. On the other hand, we can remember telephone numbers for many years through repetition; this information is said to be stored in long-term memory.

DEMENTIA

There are over 100 different types of dementia with Alzheimer's Disease being perhaps the best known. As with most forms of dementia, Alzhei-mer's involves progressive memory loss (as well as loss of other vital functions) and at present is irreversi-ble. It is not entirely clear what causes Alzheimer's but there's likely to be more than one contributing factor. On a molecular level, it involves chemical and structural changes to the brain which start killing off brain cells. In the Alzheimer brain, the cortex shrivels up, damaging areas involved in think-ing, planning and remembering. Shrinkage is especially severe in the hippocampus, an area of the cortex that plays a key role in formation of new memories. Ventricles (fluid-filled spaces within the brain) grow larger.

14

Murphy’s Law There is a tendency among human beings towards compla-

cency. The belief that an accident will 'never happen to me or to my Company' can be a major problem when attempting to convince individuals or organisations of the need to look at

human factors issues, recognise risks and implement improve-ments, rather than merely paying lip-service to human factors.

'Murphy's Law' can be regarded as the notion: 'If something can go wrong, sooner or later it will.'

If everyone could be persuaded to acknowledge Murphy's Law, this might help overcome the 'it will never happen to me' attitude that many people hold. It is not true that accidents

only happen to people who are irresponsible or sloppy. The incidents and accidents described in this publication show that errors can be made by experienced, well-respected individuals and accidents can occur in organisations previously thought to

be 'safe'.

Factors Affecting Performance: Fitness and Health ―What fits your busy schedule better: exercising

20 minutes a day or being dead 24 hours a day?‖ Fitness and health can have a significant affect upon job performance (both physical and cognitive). Day-to-day fitness and health can be reduced through illness (physical or mental) or injury. Responsibility falls upon the individual aircraft mainte-nance engineer to determine whether he is not well enough to work on a particular day. Alternatively, his col-leagues or supervisor may persuade or advise him to ab-sent himself until he feels better.

In fact, as the CAA's Air-worthiness Notice No. 47 points out, it is a legal requirement for aircraft maintenance engineers to make sure they are fit for work: 'Fitness: In most professions there is a duty of care by the indi-vidual to assess his or her own fitness to carry out professional duties.

This has been a legal requirement for some time for doc-tors, flight crew members and air traffic controllers. Licensed aircraft maintenance engineers are also now required by law to take a similar professional attitude. Cases of subtle physical or mental illness may not always be apparent to the individual but as engineers often work as a member of a team any substandard performance or unusual behaviour should be quickly noticed by col-leagues or supervisors who should notify management so that appropriate support and counselling action can be taken.'

Aircraft maintenance engineers can take common sense steps to maintain their fitness and health. These include:

Eating regular meals and a well-balanced diet

Taking regular exercise (exercise sufficient to dou-ble the resting pulse rate for 20 minutes, three times a week is often recommended)

Stopping smoking

Sensible alcohol intake (for men, this is no more than 3 - 4 units a day or 28 per week, where a unit is equivalent to half a pint of beer or a glass of wine or spirit).

Finally, day-to-day health and fitness can be adversely influenced by the use of medication, alcohol and illicit drugs.

11

Pictures from http://www.airliners.net

2004: A320 cowlings - #1 Iberia

May 11, 2004

Some minutes after take-off to Bilbao, the engine covers

flew out and the aircraft returned for an emergency

landing at Madrid (no further information available).

… and #2 AirTran Airways

On July 13, 2004, an Airbus Industrie A320-233, operated by Ryan International Airlines as AirTran Airways Flight 4, returned for landing after a portion of the left engine cowling separated from the aircraft in flight in the vicinity of Atlanta, Georgia.

The captain, first officer, 4 flight attendants and 104 passengers were not injured, and the aircraft sustained minor damage. The flight departed Hartsfield-Jackson Atlanta International Air-port, Atlanta, Georgia, at 1140 on July 13, 2004 en route to Orlando, Florida.

According to the captain, immediately after take-off, the lead flight attendant called to inform him that a passenger reported seeing a cover come off the left engine. The captain received no cockpit indications of a problem, and he instructed the lead flight attendant to look out the window and verify. The captain stated he felt the aircraft "shutter," and he contacted air traffic control and requested to return for landing. The lead flight at-tendant confirmed to the captain the left engine cowling was missing.

The captain stated the No 1 engine oil quantity indicator illumi-nated amber, and he declared an emergency. The engine con-tinued to operate normally, and the flight returned for landing without further incident.

Preliminary examination of the aircraft revealed both sides of the left engine cowling were separated, the left engine pylon was bent up, aft, and inboard and the left wing slat outboard of the engine nacelle displayed an approximate 12-inch area with dent and puncture damage.

The Union City Police Department retrieved the inboard side of the left engine cowling from a dirt roadway approximately 7.5 nautical miles west southwest of Hartsfield-Jackson Atlanta International Airport. Airport authorities found the outboard side of the left engine cowling in the grass beside runway 27R.

A mechanic later stated he opened the fan cowl for the No 1 engine prior to the flight, and he could not recall if the cowl doors were fully latched.

12

For more information on this incident, visit http://www.bea-fr.org/anglaise/rapports/rap.htm

2007: $200,000,000 Airbus A340 Written Off

16 November 2007

Airbus confirms an A340-600 was dam-

aged and five people were injured in a

ground test accident at the company‘s

Saint-Martin site in Toulouse.

The aircraft sustained damage when it

somehow broke free of its parking chocks

during engine run-ups around 5 pm, local

time. News photos taken at the scene

show the aircraft's nose rammed through

a blast deflection wall.

―At this time, recovery operations are still

in progress and Airbus staff is working

closely with the emergency services and

local authorities at the site,‖ an Airbus

statement says.

Nine people were aboard the aircraft at

the time of the accident. The condition of

the five injured person was not immedi-

ately available.

―Airbus expresses its sympathy to the

families and friends of the [injured] per-

sons concerned,‖ the company adds.

The aircraft, with tail number MSN 856,

was due to be delivered to Abu Dhabi-

based Etihad Airways, "in the coming

days," Airbus says.

French investigators have determined that

the aircraft, which was undergoing pre-

delivery checks, was being held at stand-

still with the parking brake on and all

four Rolls-Royce Trent 500 powerplants

running with a relatively high engine

pressure ratio of 1.24-1.26.

The aircraft‘s engines were not retarded

to idle until two seconds before the jet

struck its test-pen wall.

The aircraft, which had been performing

an engine and brake test, was travelling at

around 30kt (55km/h) at the time of im-

pact.

Wheel chocks were not inserted under the

aircraft at the time.

The engineers had taken all four engines

to take-off power with a virtually empty

aircraft.

The take-off warning horn was blaring

away in the cockpit because they had all

4 engines at full power. The aircraft com-

puters thought they were trying to take

off but the aircraft had not been config-

ured properly (flaps/slats, etc).

Then one of the crew decided to pull the

circuit breaker on the Ground Proximity

Sensor to silence the alarm. This fools the

aircraft into thinking it is in the air.

The computers automatically released

all the brakes and set the aircraft rocket-

ing forward. The crew had no idea that

this is a safety feature so that pilots can't

land with the brakes on.

“AIRBUS REMINDS ALL OPERATORS TO

STRICTLY ADHERE TO AIRCRAFT MAINTENANCE MANUAL PROCEDURES

WHEN PERFORMING ENGINE GROUND

RUNS.

ENGINE GROUND RUNS AT HIGH POWER ARE NORMALLY CONDUCTED ON A SIN-

GLE ENGINE WITH THE ENGINE IN THE

SAME POSITION ON THE OPPOSITE

WING OPERATED AT A LIMITED THRUST SETTING TO AVOID DAMAGE TO THE

AIFRAME.

WHEEL CHOCKS ARE TO BE INSTALLED

THROUGHOUT THE TEST.”

YANNICK MALINGE

VICE PRESIDENT FLIGHT SAFETY

AIRBUS

20 Nov 2007

13

April 2010: Polish president killed in Tu-154 crash

Polish president Lech Kaczynski is

among some 90 people killed after a governmental Tupolev Tu-154 crashed near the Russian city

of Smolensk. The Polish presidential office con-

firms that Kaczynski, his wife Ma-ria and dozens of senior Polish representatives were on board

the aircraft.

It states that preliminary information suggests the air-

craft struck trees at the end of the runway while at-tempting a go-around. Weather conditions were report-edly poor, including fog, but meteorological information

from the airport has yet to be confirmed, as is a report that the Tu-154's crew was offered a diversion.

The main questions that arise relate to the decision to send so many national leaders on a single flight, and why

the aircraft's crew made the disastrous attempt to carry out an approach when visibility was well below the mini-mum for the non-precision approach. Other questions

relate to why the navigation aids available at Smolensk were not supplemented for a flight carrying such a high-profile delegation. The aircraft, arriving from Warsaw on

10 April, had been approaching runway 26 at Smolensk North in fog. Images from the scene show that the jet's wreckage is displaced to the left of the runway's extend-

ed centreline, and that the direction of the debris trail bears some 30° to the left.

CIS Interstate Aviation Committee (MAK) leader Tatyana Anodina has stated that the Soloviev D-30KU engines were "in working order" until the aircraft collided with an

obstacle. She added that preliminary analysis of the re-corders showed no evidence of in-flight fire or explosion or on-board equipment failure.

In addition, communications with the aircraft were nor-mal, and the pilots did not report any problems to air traffic control.

Smolensk ATC says it had, however, suggested to the pilots that they consider diverting to Minsk or Vitebsk in

Belarus, or Moscow Vnukovo.

The problem with those airports is that they are all more than four hours by road from Katyn, the ultimate destina-

tion for the Polish delegation, where they were to attend a commemoration of a massacre of Polish officers 70

years ago during the Second World War. Diverting would have made the officials late for the scheduled ceremony.

The Tu-154M's 35-year-old captain had a total of 3,528h, of which 2,937h were on Tu-154 aircraft. His co-pilot had 506h on the type from an overall 1,939h. There was also

a navigator on board, who had 59h on the Tu-154 but had also flown as a Yakovlev Yak-40 pilot, as well as a senior technician.

Flight International