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HUMAN FACTORS IN AIRCRAFT MAINTENANCE RELATEDACCIDENTS AND INCIDENTS
by
George Leath
A Graduate Research Project (Proposal) Submitted to the ExtendedCampus in Partial Fulfillment of the Degree of
Master of Aeronautical Science
Embry - Riddle Aeronautical UniversityExtended Campus
Houston Resident CenterApr-23
HUMAN FACTORS IN AIRCRAFT MAINTENANCE RELATEDACCIDENTS AND INCIDENTS
by
George Leath
This Graduate Research Project (Proposal)was prepared under the Direction of the candidate’s Research Committee
Member, Mr. Wesley Zubkow Instructor, Extended Campus,and the candidate’s Research Committee Chair,
Dr. Walter Sipes, Associate Professor, Extended Campus, and has been approved by the Project Review Committee. It was submitted to the
Extended Campus in Partial Fulfillment of the Degree ofMaster of Aeronautical Science
PROJECT REVIEW COMMITTEE
_____________________________Mr. Wesley ZubkowCommittee Member
_____________________________Dr. Walter SipesCommittee Chair
ii
ACKNOWLEDGEMENTS
The writer wishes to express special thanks to his Research Committee Chair,
Ph. D. and Committee Member, for their valuable guidance and inspiration
throughout the entire research process. Additional thanks to my family for their
patience, understanding, and assistance. Special thanks is due to and his
Houston Center staff for their support and guidance, without their special help
and encouragement, this study could not have been completed.
iii
ABSTRACT
Researcher: George Leath
Title: HUMAN FACTORS IN AIRCRAFT MAINTENANCE RELATED ACCIDENTS AND INCIDENTS
Institution: Embry-Riddle Aeronautical University
Degree: Master of Aeronautical Science
Year: 2003
Aviation accident statistics reveal that maintenance errors were a contributing
factor in 12% of aircraft accidents and incidents. An in-depth review of aviation
case studies indicate, that a series of human errors was allowed to form until the
accident or incident occurred. Human Factors (HF) has emerged as critical to
the safety of aviation maintenance, the industry responded by introducing HF
training. HF training has been mandated by the Federal Aviation Administration
(FAA). This research examined the effect HF training has had on the occurrence
of aviation maintenance errors and to make recommendations for future
improvements. The data was retrieved from databases maintained by the FAA
and the National Transportation Safety Board (NTSB).
iv
TABLE OF CONTENTS
Page
PROJECT REVIEW COMMITTEE ii
ACKNOWLEDGEMENTS iii
ABSTRACT iv
LIST OF TABLES vii
LIST OF FIGURES viii
I INTRODUCTION 1
Background of the problem 1
Statement of the Problem 5
Sub Problems 5
Hypothesis 6
Assumptions and Delimitations 6
Definition of Terms 7
II REVIEW OF RELEVELANT LITERATURE AND RESEARCH 8
Introduction to the Literature 8
Academic and Private Sector Participation 9
Government Involvement 10
Industry Efforts 14
Statement of the (Hypothesis or Research Question) 22
v
III RESEARCH METHOLODGY 23
Research Design 23 Research Model 23
Observation Criteria 23
Sources of Data 24
The Data Gathering Device 24
Distribution Method 24
Reliability 25
Validity 25
Treatment of Data and Procedures 25
IV RESULTS 9
V DISCUSSION 10
VI CONCLUSION 11 VII RECOMMENDATIONS 12 REFERENCES 22
APPENDICES
A BIBLIOGRAPHY 14
B PERMISSON TO CONDUCT 16
C DATA COLLECTION DEVICE (an example) 17
D TABLES 22
E FIGURES 24
vi
LIST OF TABLES
vii
LIST OF FIGURES
Figure Page
1 Aloha Airlines Accident 1
2 Typical Aircraft Maintenance Department 4
3 Typical Aviation Communications 5
4 MEDA Process Flow 17
viii
ix
CHAPTER I
INTRODUCTION
Background of the Problem
Aviation is considered one of the safest means of travel in the world today,
yet every now and then, an accident or incident occurs which shakes us out of
complacency. Aviation history abounds with descriptions of accidents and
incidents attributable to maintenance error. An in-depth review of actual aviation
case studies will reveal, time and time again, that a series of human errors (known
as a chain of events) was allowed to form until the accident or incident occurred
(Shepherd, 1991). One of the most spectacular was the Aloha Airlines accident in
Hawaii on April 28, 1988. In this event, the forward upper fuselage of the aircraft
separated in-flight from a point near the floor line (see figure 1).
Figure 1. Aloha airlines accident. Note. From Embry-Riddle Aeronautical University DCE web page, 2002
1
Passengers seated in this area were pummeled by slipstream and flailing
structural wreckage, but through a combination of extreme good fortune and pilot
skill, the airplane was landed with the unfortunate loss of one life, a flight
attendant, who was standing in the aisle at the moment the surrounding structure
disintegrated. Subsequent investigation revealed that the airplane had been
showing plenty of signs of impending structural failure but the airline’s
maintenance staff had overlooked these.
A commuter airline accident highlights the importance of communication
and work conditions in aircraft maintenance. A Continental Express Embraer
Brasilia was undergoing routine maintenance in the evening prior to its dispatch to
service the following morning. One of the tasks that was to be performed was the
replacement of the horizontal stabilizer de-ice boots. One of the boots was
successfully removed and replaced; however, the second boot installation was
only partly completed by one shift of workers. The following work shift was not
informed of the incomplete status of the boot repair. Numerous attaching screws
on the upper surface had been left out. Incoming workers examined the T-tail
surface from the ground with a flashlight, since the aircraft was being worked on in
darkness outside the hangar. Since the structure appeared to be in good order,
the aircraft was dispatched for service. In a subsequent flight the boot separated
from the stabilizer resulting in structural failure of the empennage and loss of the
aircraft with all aboard.
Following the Aloha Airlines accident, the Office of Aviation Medicine (AAM)
was tasked by the Offices of Airworthiness and Flight Standards to take a closer
2
look at aircraft maintenance Human Factors (HF) issues. A review of HF research
revealed an almost total lack of information concerning the factors that affect the
performance of Aircraft Maintenance Technicians (AMTs). Hundreds upon
hundreds of studies and reports exist related to pilot and air traffic controller
performance, but virtually nothing on mechanics and inspectors. This lack of
research is somewhat puzzling, in view of the demonstrable fact that maintenance
error can have just as devastating a result as pilot or air traffic controller error.
The AAM research program has concluded that most HF problems in aircraft
maintenance belong to one or more of the following categories (see figure 2):
The worker
The workplace
Communication
Training
Figure 2. Typical aircraft maintenance department. Note. From Embry-Riddle Aeronautical University DCE web page, 2002
3
“Accident statistics reveal that maintenance errors were a contributing
factor to the chain of events in 12% of major airplane accidents many, if not most,
of these accidents involved some degree of human error “(Shepherd, 1991).
When we look at an aviation accident or incident where maintenance had a
contributing link in the chain of events we sit back and wonder how could this have
happened with all the Regulatory Compliance Programs that are imposed on the
industry today. In some cases the error itself was the primary cause of the
accident, whereas in other cases, the resulting maintenance discrepancy was just
one link in the chain of events that led to the accident. As HF has emerged as
critical to the safety of maintenance, a major response by the industry has been to
introduce HF training. The natural response is "If HF are such a problem, then let's
train our technicians in HF" (Cronie, 1999). HF training, commonly called
Maintenance Resources Management (MRM), has been developed by airlines,
manufacturers and training organizations and has been mandated by the Joint
Aviation Authority / Federal Aviation Administration (JAA / FAA). The industry is
committed to training as a remedy for human factors problems. “If we can break
the chain of events at the maintenance level, the accident will not likely happen”
(Shepherd, 1991). A further study of such cases shows that there could have
been safety nets put in place in the maintenance department to prevent this
incident from ever happening. HF re-emphasizes the requirements for the
workforce to create safety nets in the workplace.
At a time when aviation organizations increasingly expect employees to
work with minimal supervision and to show more initiative, competent
4
communication skills are becoming a must. Without communication in
maintenance, not a single aircraft could safely leave the ground. “The type and
level of communication that must go on among operators, manufacturers,
designers, records keepers, passengers, pilots, dispatchers, trainers, students, the
public, government authorities (the list is seemingly endless) is positively mind-
boggling” (Shepherd, 1991), as shown in figure 3.
Figure 3. Basic aviation communication. Note. From Galaxy scientific corporation, 2002.
Statement of the Problem
In the days of the DC-3, there were only a few airplanes and their maintenance
requirements were, by today’s standards, decidedly “low-tech” (Cronie, 1999). “Today HF
related to some type of maintenance error has contributed to 12% of all major aircraft
accidents / incidents” (Cronie, 1999). This research is interested in determining exactly what
impact the mandated Aviation Safety Research Act of 1988, (which, specifically authorized
5
research to be performed by AAM) has had on maintenance error in aviation accidents and
incidents. AAM’s goal was to reduce maintenance-related accidents and incidents resulting
from human error by 20% by the year 2003.
Statement of the Hypothesis
Null (Ho) - The introduction off MRM into aviation maintenance has reduced
maintenance human error related aircraft accidents and incidents.
Alternate (Ha) – The introduction of MRM Training in aviation maintenance has not
reduced maintenance human error related aircraft accidents and incidents.
Assumptions
This research is being accomplished for the sole purpose of fulfilling the
requirements of the MAS program at Embry Riddle Aeronautical University; no
outside funding will either be provided or solicited. It will be completed in a timely
manner based on the researchers resources and capabilities, and university
guidelines. All incidents and accidents were investigated by the NTSB or the FAA,
and all data facts will be presented unbiased, and as they where discovered.
Delimitations
The data collected will be from United States General Aviation and United
States Commercial Air Carriers only. Foreign or military data will not be included in
this research; this will be a study of data submitted before and after MRM training.
6
Definition of TermsA/C Aircraft
AAIB Air Accidents Investigation Branch
AAM Office of Aviation Medicine
AANC (US) Ageing Aircraft Inspection Validation Center
AAR Office of Aviation Research
AD Airworthiness Directive
ADAMS (Human Factors) in Aircraft Dispatch and Maintenance
AIDS Accident and Incident Data System
AMC Acceptable Means of Compliance (for JARs)
AME Aircraft Maintenance Engineer
AMPOS Aircraft Maintenance Procedure Optimization System
AMT Aircraft Maintenance Technician
AOG Aircraft On the Ground
ASRS Aviation Safety Reporting System
ATA Air Transport Association of America
ATC Air Traffic Control
AWN Airworthiness Notice
BASIS British Airways Safety Information System
BASIS MEI BASIS Maintenance Error Investigation
BCAR British Civil Airworthiness Requirements
CAA (UK) Civil Aviation Authority
CAMC Canadian Aviation Maintenance Council
7
CARMAN Consensus Based Approach to Risk Management
CASA (Australian) Civil Aviation Safety Agency
CBT Computer Based Training
cd candela
CEO Chief Executive Officer
CFS Chronic Fatigue Syndrome
CMI Computer Managed Instruction
CRM Crew Resource Management
DDA Document Design Aid
DOD Department of Defense
DOE Department of Energy (USA)
DOT Department of Transportation
ERAU Embry Riddle Aeronautical University
ERNAP Ergonomics Audit Program
FAA Federal Aviation Administration
FAR Federal Aviation Regulation
FEMA Failure Modes and Effects Analysis
fL footLambert
FODCOM Flight Operations Department Communication
GAIN Global Aviation Information Network
HAZOP Hazard and Operability study/ assessment
HF Human Factors
8
HFRG (UK) Human Factors in Reliability Group
HRA Human Reliability Assessment
HSE (UK) Health and Safety Executive
IBT Internet Based Training
ICAO International Civil Aviation Organization
IEM Interpretative/ Explanatory material (for JARs)
IES (US) Illuminating Engineering Society
IFA International Federation of Airworthiness
IMIS Integrated Maintenance Information System
JAA Joint Aviation Authority (European)
JAR Joint Aviation Requirement
LAE Licensed Aircraft Engineer
lm lumen
LOFT Line Oriented Flying Training
lux lumens/m²
MARSS Maintenance and Ramp Safety Society
MEDA Maintenance Error Decision Aid
MEDA Maintenance Engineering Decision Aid
MEMS Maintenance Error Management System
MEMS FMS Maintenance Error Management System Free MEDA
Software
MESH Maintenance Engineering Safety Health
9
MHFWG JAA Maintenance Human factors Working Group
MM Maintenance Manual
MOE Maintenance Organization Exposition
MOR (UK) Mandatory Occurrence Report
MRM Maintenance Resource Management
NAA National Aviation Authority
NAS National Airspace System
NASA National Aeronautics Space Administration
NASA TLX NASA Task Loading Index
NASDAC National Aviation Safety Data Analysis Center
NDI Non-Destructive Inspection
NDT Non-Destructive Testing
NPA Notice of Proposed Amendment (for JARs)
NTSB National Transportation Safety Board
OJT On-the-Job Tuition
OSHA Occupational Safety and Health Administration
PC Personal Computer
PRA Probabilistic Risk Assessment
PSA Probabilistic Safety Assessment
R&D Research and Development
REM Random Eye Movement
ROI Return on Investment
10
SA Situational Awareness
SB Service Bulletin
SHEL Model Software, Hardware, Environment, Liveware
SMM Shift Maintenance Manager
SMS Safety Management Systems
STAMINA (Human Factors) Safety Training for the Aircraft Maintenance
Industry
SWAT Subjective Workload Assessment Technique
TC holder Aircraft Type Certificate holder
TGL Temporary Guidance Leaflet (for JARs)
TQM Total Quality Management
TWA Time Weighted Average sound level
UK HFCAG UK Human Factors Combined Action Group
UK OTG UK Operators’ Technical Group
UK RAF SAM UK Royal Air Force School of Aviation Medicine
VIRP (US) Visual Inspection Research Program
11
CHAPTER II
REVIEW OF RELEVELANT LITERATURE AND RESEARCH
Introduction to the Literature
Aircraft accidents and incidents are events that involve direct or potentially
direct effects on the safety of aircraft operations and of persons involved in those
operations. Accidents result in death or serious injury to a person in, upon, or
about the aircraft, or in substantial damage to the aircraft itself. Incidents are less
serious events "that affect or could affect the safety of operations." (FAA, 1996b).
The literature review will examine various studies of HF related to aviation
maintenance, which is one of the most promising means of increasing aviation
safety (Shepherd, 1997).
In the following studies and or research the authors attempt to explore how
HF tries to identify and reduce the chances for human error through improvements
in design and training. HF related aviation accidents and incidents remain
subjects of great public concern. Despite the aerospace industry's success at
developing ever more sophisticated and reliable technology, the proportion of
human error-related accidents and incidents remains remarkably constant (Kraus,
1998). This fact, combined with expected growth rates and the requirement to
12
increase productivity, has resulted in considerable attention to HF research and
application programs over the last several years (Shepherd, 1997). Valuable
programs in aviation human factors have been underway for many years at the
FAA, NASA, and DOD, as well as in academic and industry sectors.
Academic and Private Sector Contribution
Embry-Riddle Aeronautical University (ERAU) offers a workshop on HF In
Aircraft Maintenance, the workshop focuses on the variety of HF that come into
play in the course of an AMT’s work. The workshop is specifically for aircraft
technicians, and their supervisors. Aircraft maintenance is a training orientated
industry. General and specific competencies are developed through basic and
type training. These competencies are enhanced and updated through continuous
training. If an inadequacy is identified, a new type of aircraft is purchased or new
maintenance techniques developed, appropriate courses are sought out for AMT,s
(Cronie, 1999).
As HF has emerged as critical to the safety of maintenance, a major
response by the industry has been to introduce HF training. The natural response
is "If HF are such a problem, then let's train our technicians in human factors."
(Cronie, 1999). HF training has been developed by airlines, manufacturers and
training organizations and has been mandated by the JAA and FAA. The industry
is committed to training as a remedy for HF problems (Cronie, 1999). A review of
HF research by AAM, revealed an almost total lack of information concerning the
factors that affect the performance of AMT, s. “Hundreds upon hundreds of
13
studies and reports exist related to Pilots and Air Traffic Controllers (ATC,s)
performance, but virtually nothing on mechanics and inspectors. This lack of
research is somewhat puzzling, in view of the demonstrable fact that maintenance
error can have just as devastating a result as pilot or air traffic controller error”
(Shepherd, 1991).
The AAM research program has concluded that most human factors
problems in aircraft maintenance belong to one or more of the following
categories:
The Worker
Aircraft maintenance is frequently performed at night because most flights are
conducted during the day. Physiologically and mentally, we are most alert during
daytime hours and prefer to rest or sleep during nighttime hours. Many people find
it difficult to disturb this pattern. When they are required by their jobs to sleep
during the day and work at night, work performance deficits frequently ensue. This
effect can clearly have serious implications for aviation safety. The result can be a
fatigued technician with a greater tendency toward work error. AAM research is
evaluating the effects of shift work and fatigue on technician performance and has
developed software that allows maintenance managers to assess the “degree of
difficulty” of tasks and to make appropriate work assignments.
The workplace
Aircraft maintenance workplaces can range from climate-controlled, well-lit,
relatively quiet hangars to nighttime, outdoor, noisy ramps in cold, rainy weather.
Obviously, the first set of conditions is preferred to the second because it is likely
14
to foster error-free and efficient work. On the other hand the conditions in the
second example, individually or collectively will likely impair technician
performance. Noise on ramps from aircraft operations, or in hangars from riveting
or power unit operation, can be distracting, have obvious health implications, may
result in heightened response of the human autonomic nervous system, and often
increase fatigue. Lighting in aircraft maintenance, particularly on inspection tasks,
can mean the difference between flaw detection and non-detection; between a
correct or incorrect repair. Flashlights are frequently seen in aircraft maintenance.
They can be very useful in illuminating areas that are not lit by ambient lighting,
but they also often encumber the use of one hand, making it difficult to perform
some tasks. Also, flashlights often lack the brightness needed for some jobs.
Better solutions entail use of portable lighting that can be easily moved or affixed
to an adjacent structure.
Communication
In the days of the DC-3, maintenance communication was relatively
straightforward. There were only a few airplanes and their maintenance
requirements were, by today’s standards, decidedly “low-tech.” A single recent
example shows how much change has occurred. In 1988, Boeing Commercial
Airplane Company’s publication activity included maintaining 1,126 active manuals
for 5,300 airplanes and 425 worldwide operators. This amounts to nearly 20 million
page sets, with each manual being revised about every 120 days. Boeing
publishes a paper stack every year that exceeds the height of Mt. Everest. Most, if
not all, major airframe manufacturers now produce their maintenance
15
documentation in electronic form. A technician can now access maintenance
information from tape or disc and present it on a video terminal. With these recent
enhancements in computer capabilities, it is now possible, for example, to perform
full text searches for key words, to display information one page at a time, or
jumping through several pages at a time, to have the computer lead the user to
related information located in several different sources, or to use the system for
on-line training and job-aiding. AAM is working with a number of airlines to develop
and evaluate some of these innovative electronic systems under actual working
conditions. AAM is evaluating PEN-Based computer systems in aircraft
maintenance and for use by FAA Aviation Safety Inspectors. These systems allow
rapid access to stored information such as regulations, airworthiness directives,
repair procedures, and parts lists. PEN computers also have on-screen written
input capabilities, which with a special stylus and hand writing recognition software
permit the user to file reports, fill out forms, and provide input to main frame
computer data bases. By some estimates, paperwork now consumes 25% of
available technician and inspector time.
If these new systems could reduce this odious communication burden by
even a few percent, there would be dramatic improvements in the bottom-line
performance of FAA inspection and airline maintenance organizations by making
this time available for the work the technicians and inspectors are hired for. AAM
research on these systems is providing a head start to airlines and FAA on
automating systems that are currently heavily paper oriented.
16
Training
New training technologies are being studied by AAM along with the new
communication technologies described in the previous paragraph. These new
training methods can be used to supplant or supplement on-the-job-training at the
work site, or more formal classroom and laboratory training, as found in technician
training schools. New training technology might be loosely defined as training with
computers. This can include such methods as time-tested computer-based
instruction, interactive videodisc, computer-controlled simulators, computer-
controlled real equipment, and computer-based testing.
AAM’s research into aircraft maintenance human factors is one of only a few
leading-edge projects worldwide in this area. It is already paying dividends through
heightened awareness of the importance of technician performance to flight safety.
However, the real payoffs will come later, when the AAM-developed systems,
tools, and technology are in regular use within FAA and the airline industry. AAM
currently has ongoing research tasks in each of these areas.
Government Involvement
The Human Factors Division (AAR-100) of the FAA provides scientific and
technical support for the civil aviation human factors research program and for
human factors applications in acquisition, certification, regulation, and standards. It
develops and assures implementation of human factors policies, regulations,
programs, and procedures, which promote the safety and productivity of the
National Airspace System (NAS). It also formulates and manages the aviation
17
human factors research program and provides human factors support to
acquisition and regulatory activities. The U.S. civil air carrier fleet requires a well-
trained and accountable maintenance workforce to provide continuing safe and
reliable air transportation. However, acquiring this workforce is a growing problem
due to a shortage of Aviation Maintenance Technicians (AMT, s) to support an
ever-increasing number of aircraft. The linchpin of this system is the human,
recognizing this the FAA has pursued human factors research by placing an
increased emphasis on technical and human factors training. Previously, the
training concerns of the aircraft maintenance environment had focused on
technical / procedural skills. But, these training issues need to be supplemented
with maintenance human factors training at the same level and with the same
emphasis as crew resource management (FAA, 1996), (human factors training for
the flight deck crews).
The NTSB maintains a database on aircraft accidents and serious incidents,
and also publishes hardcopy reports on the most serious accidents. The FAA
maintains the Accident and Incident Data System (AIDS), which contains
information on incidents, and also maintains specialized databases on specific
types of incidents. Specialized FAA incident databases include human factor
issues such as Pilot Deviations, Near Midair Collisions, and Operational and
Maintenance Errors. In addition, the Aviation Safety Reporting System (ASRS)
database contains voluntary reports of safety incidents. The FAA collects and
reports (e.g., FAA (1996b) a variety of data that can be used to measure or
evaluate air carrier safety and the safety of the aviation system. Most data
18
reported today looks at safety levels in a highly aggregated format. Databases
containing information on NTSB aviation accident reports and safety
recommendations are available online at the FAA's Office of System Safety
homepage. Monthly flight hours and accident and incident rates for large air
carriers, commuters, air taxis, general aviation, and rotorcraft are also available in
the Aviation System Indicators at this web site. Descriptive information is available
for individual airlines from the carriers themselves and in the Vital Information
Subsystem. There are a wide variety of aviation events that are categorized as
aviation incidents; information on these is available at FAA's National Aviation
Safety Data Analysis Center (NASDAC) system. All of these accident and incident
data are available to the public. Because accidents and incidents, once reported
and investigated, are believed to represent a relatively unambiguous record of
unfavorable safety events, they are the safety measures most commonly used by
researchers for analyzing changes in aviation safety over time and differences
among carriers and groups of carriers. However, the raw data on accidents and
incidents must be converted to accident and incident rates before it can
legitimately be used for making comparisons about safety over time, among
groups of carriers, or among individual carriers. This type of conversion, is called
normalization and some observers have suggested that the classification scheme
for aviation accidents used by reporting agencies is needlessly arcane, and the
Federal Aviation Authorization Act of 1996 directs the NTSB, in conjunction with
FAA, to develop a more comprehensible and refined classification of accidents
involving fatalities, injuries, or substantial damage. (Congress House, 1996).
19
The NTSB has recently responded with a proposed classification format that
addresses these concerns, (NTSB, 1996). Computation of an accident or incident
rate requires normalizing information about the level of exposure to risk. For
comparative purposes, it is essential that accident and incident data be normalized
in some way, since the system's exposure to risk changes over time. Accident
and incident rates commonly reported to the public by FAA, the NTSB, and
intermediaries such as the media and consumer groups thus combine event data-
accident counts and incident counts-with exposure data to provide a measure of
the frequency with which events have occurred. This study will try and relate the
maintenance department and associated human factors into the accident and
incident rates.
Industry Efforts
As a result of the 1997 merger with McDonnell Douglas, the Maintenance
Error Decision Aid (MEDA) process offered by Boeing is now available to
operators of Douglas-designed commercial airplanes and their maintenance
organizations (Allen, Rankin, and Sargent, 1998) Since its introduction two years
ago, a growing number of maintenance organizations for Boeing-designed
airplanes have adopted MEDA, which is a tool for investigating the factors that
contribute to maintenance errors. MEDA provides a comprehensive approach for
conducting thorough and consistent investigations, determining the factors that
lead to an error, and making suggested improvements to reduce the likelihood of
future errors. Maintenance errors cost operators of commercial airplanes millions
of dollars each year in rework and lost revenue, and present potential safety
20
concerns. For example, aviation industry studies indicate that as many as 20
percent of all in-flight engine shut downs and up to 50 percent of all engine-related
flight delays and cancellations can be traced to maintenance error, Allen et al.
(1998).
In response, Boeing developed the MEDA process to help maintenance
organizations identify why these errors occur and how to prevent them in the
future. Successful implementation of MEDA requires an understanding of the
following:
The MEDA Philosophy
Traditional efforts to investigate errors are often aimed at identifying the employee
who made the error. The usual result is that the employee is defensive and is
subjected to a combination of disciplinary action and recurrent training. Because
retraining often adds little or no value to what the employee already knows, it may
be ineffective in preventing future errors. In addition, by the time the employee is
identified, information about the factors that contributed to the error has been lost.
Because the factors that contributed to the error remain unchanged, the error is
likely to recur, setting what is called the "blame and train", Allen et al., cycle in
motion again. To break this cycle, the maintenance organization's MEDA
investigators learn to look for the factors that contributed to the error, rather than
the employee who made the error. The MEDA philosophy is based on these
principles:
21
positive employee intent.
Maintenance technicians want to do the best job possible and do not make errors
intentionally). Contribution of multiple factors (a series of factors contributes to an
error). Manageability of errors (most of the factors that contribute to an error can
be managed). This principle is key to a successful investigation. Traditional
"blame and train" Allen et al., investigations assume that errors result from
individual carelessness or incompetence. Starting instead from the assumption
that even careful employees can make errors, MEDA interviewers can gain the
active participation of the technicians closest to the error. When technicians feel
that their competence is not in question and that their contributions will not be
used in disciplinary actions against them or their fellow employees, they willingly
team with investigators to identify the factors that contribute to error and suggest
solutions. By following this principle operators can replace a negative "blame and
train" pattern with a positive "blame the process, not the person" (Allen et al)
practice.
contribution of multiple factors.
Technicians who perform maintenance tasks on a daily basis are often aware of
factors that can contribute to error. These include information that is difficult to
understand, such as work cards or maintenance manuals; inadequate lighting;
poor communication between work shifts; and airplane design. Technicians may
even have their own strategies for addressing these factors. One of the objectives
of a MEDA investigation is to discover these successful strategies and share them
with the entire maintenance operation.
22
manageability of errors.
Active involvement of the technicians closest to the error reflects the MEDA
principle that most of the factors that contribute to an error can be managed.
Processes can be changed, procedures improved or corrected, facilities
enhanced, and best practices shared.
Because error most often results from a series of contributing factors, correcting or
removing just one or two of these factors can prevent the error from recurring.
The MEDA Process
To help maintenance organizations achieve the dual goals of identifying
factors that contribute to existing errors and avoiding future errors, Boeing initially
worked with British Airways, Continental Airlines, United Airlines, a maintenance
workers' labor union, and the U.S. Federal Aviation Administration, Allen et al. The
result was a basic five-step process for operators to follow (see figure 4).
23
EVENT OCCURS
Investigation reveals event caused by maintenance error
DECISION
INVESTIGATION
Determine who made the error Interview responsible personnel
- Find contributing factors- Get ideas for progress improvement
Follow up to obtain additional contributing factors and information
Add to maintenance error database
PREVENTION STRATEGIES
Make process improvements based on contributing factors
- Based on this event- Based on analysis of data for
multiple events
FEEDBACK
Provide feedback to all employees affected by process improvements
Figure 4. MEDA process flow. Note. From the Boeing company 1998
event.
An event occurs, such as a gate return or air turn back. It is the responsibility of
the maintenance organization to select the error-caused events that will be
investigated.
decision.
After fixing the problem and returning the airplane to service, the operator makes a
decision: Was the event maintenance-related? If yes, the operator performs a
MEDA investigation.
investigation.
Using the MEDA results form, the operator carries out an investigation. The
trained investigator uses the form to record general information about the airplane,
when the maintenance and the event occurred, the event that began the
investigation, the error that caused the event, the factors contributing to the error,
and a list of possible prevention strategies.
prevention strategies.
The operator reviews, prioritizes, implements, and then tracks prevention
strategies (process improvements) in order to avoid or reduce the likelihood of
similar errors in the future.
Feedback.
The operator provides feedback to the maintenance workforce so technicians
know that changes have been made to the maintenance system as a result of the
24
MEDA process. The operator is responsible for affirming the effectiveness of
employees' participation and validating their contribution to the MEDA process by
sharing investigation results with them. MEDA is a long-term commitment, rather
than a quick fix. According to Dr. Jim Reason, professor of psychology at the
University of Manchester, MEDA is "a good example of a measuring tool capable
of identifying accident-producing factors before they combine to cause a bad
event",
Management Resolve.
The resolve of management at the maintenance operation is key to
successful MEDA implementation. Specifically, after completing a program of
MEDA support from Boeing, managers must assume responsibility for the
following activities before starting investigations:
1. Appoint a manager in charge of MEDA and assign a focal organization.
2. Decide which events will initiate investigations.
3. Establish a plan for conducting and tracking investigations.
4. Assemble a team to decide which prevention strategies to implement.
5. Inform the maintenance and engineering workforce about MEDA before implementation.
MEDA is a long-term commitment, rather than a quick fix. Operators new to
the process are susceptible to "normal workload syndrome." This occurs once the
enthusiasm generated by initial training of investigation teams has diminished and
the first few investigations have been completed. In addition to the expectation that
they will continue to use MEDA, newly trained investigators are expected to
25
maintain their normal responsibilities and workloads. Management at all levels can
maintain the ongoing commitment required by providing systematic tracking of
MEDA findings and visibility of error and improvement trends.
Implementing MEDA
Many operators have decided to use MEDA initially for investigations of
serious, high-visibility events, such as in-flight shut downs and air turn backs. It is
easy to track the results of such investigations, and the potential "payback" is very
noticeable. In contrast, according to David Hall, deputy regional manager in the
British Civil Aviation Authority (CAA) Safety Regulation Group, a high-visibility
event may not present the best opportunity to investigate error. The attention of
operators' upper management and regulatory authorities could be intimidating to
those involved in the process. In addition, the intensity of a high-level investigation
may generate too many possible-contributing factors to allow a clear-cut
investigation of the event. Hall has recommended that operators look at the
broader potential for improvement by using MEDA to track the cumulative effects
of less-visible errors. Providing management visibility of the most frequently
occurring errors can, in the long run, produce profound improvements by
interrupting the series of contributing factors. According to Dr. Jim Reason,
professor of psychology at the University of Manchester, MEDA is "a good
example of a measuring tool capable of identifying accident-producing factors
before they combine to cause a bad event."
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The Benefits of MEDA
About 60 operators have already implemented some or all of the MEDA
process. Participating airlines have reported several benefits, including the
following improvements:
A 16 percent reduction in mechanical delays.
Revised and improved maintenance procedures and airline work
processes.
A reduction in airplane damage through improved towing and headset
procedures.
Changes in the disciplinary culture of operations.
Elimination of an engine servicing error by purchasing a filter-removal tool
that had not previously been available where the service was being
performed.
Improvements in line maintenance workload planning.
A program to reduce on-the-job accidents and injuries based on the MEDA
results form and investigation methods.
The MEDA process offered by Boeing continues to help operators of airplanes
identify what causes maintenance errors and how to prevent similar errors in the
future. Because MEDA is a tool for investigating the factors that contribute to an
error, maintenance organizations can discover exactly what led to an error and
remedy those factors. By using MEDA, operators can avoid the rework, lost
revenue, and potential safety problems related to events caused by maintenance
errors.
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Statement of the (Hypothesis or Research Question)
Recently it has been more widely acknowledged that aircraft maintenance requires
human factors resources like with those that have been applied to other aspects of
aviation. The general causes of human error and the means for error prevention,
originate in basic human capabilities, limitations and training (Royal Aeronautical
Society, 1991). In aircraft maintenance there is a small margin for error, for a set
of tasks done day in and day out, a set of tasks that can determine the outcome of
hundreds of passengers. To the AMT, these tasks can become routine causing
them to inadvertently skip steps in a maintenance procedure. This research is
concerned with past statistical studies that show that 12% of aircraft accidents and
incidents involved some form of human factor error. The Aviation Safety Research
Act of 1988 specifically authorizes research to be performed by the Office of
Aviation Medicine. It’s goal was to reduce maintenance-related accidents and
incidents resulting from human error by 20% by the year 2003, by implementing
Maintenance Resource Management (MRM) training curricula and techniques.
This research will collect data on major accidents and incidents for a prescribed
period to determine exactly what affect MRM training has had on human error
elated aircraft accidents and incidents.
CHAPTER III
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RESEARCH METHOLOGY
Research Design
The research design will be a Time – Series Experiment consisting of making a
series of observations of aviation accident and incident investigation data
contained in government databases.
Research Model
The study is intended to develop and validate an observation instrument that
assesses the affect Human Factors Training (MRM) has had on the frequency of
maintenance error occurrences in aviation maintenance related accident and
incident probable cause data. Three year observations will be made before the
implementation of MRM, and an additional three year observations will be
conducted after MRM was officially introduced and a comparison will be made of
the results.
Observation Criteria
The Aviation Safety Research Act of 1988 specifically authorizes research to be
performed by the Office of Aviation Medicine. It’s goal was to reduce
maintenance-related accidents and incidents resulting from human error by 20%
by the year 2003. Creation and distribution of MRM prototype training materials
for airline use were developed, implemented, evaluated and distributed by 1998
and beyond as requirements dictate. Observations will be taken three years prior
to implementation of MRM (1988) and the three years prior to 2003.
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Sources of Data
The observation data will be taken from The NTSB aviation accident database
which contains information from 1962 and later about civil aviation accidents and
incidents within the United States, its territories and possessions, and in
international waters. Generally, a preliminary report is available online within a few
days of an accident. Factual information is added when available, and when the
investigation is completed, the preliminary report is replaced with a final
description of the accident and its probable cause. Full narrative descriptions may
not be available for dates before 1993, cases under revision, or where NTSB did
not have primary investigative responsibility.
The Data Gathering Device
The author will utilize a computerized approach of collecting and organizing the
data, the data will be extracted from NTSB, and FAA accident / incident
investigation data basses and organized into spreadsheets or tables designed to
test the stated hypothesis. The world wide web, ERAU’s library resources, and
local public libraries will be the sources of information.
Reliability
All accidents / incidents included in the observations will include NTSB / FAA ID
numbers and dates to ensure data can be linked to an actual accident and for
follow up research purposes.
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Validity
Factors such as:
The researcher's holds an FAA airframe power-plant mechanic certificate and
has 25 plus years in aviation maintenance, both as an Inspector and Mechanic.
The strict methodology used to gather, organize, test, and conduct the
experiment enhanced the validity of this study and the fact that the data was
retrieved from official accident and incident investigations.
Treatment of Data and Procedures
All data will be retrieved from government data basses and will show the human
errors involved in aircraft accidents / incidents before and after MRM was
introduced into the system.
CHAPTER IV
RESULTS
The results of this experiment are described in the following summary tables, the
raw data is contained in tables located in Appendix D. The NTSB concluded
10,099, aviation investigations from 1983 to 1985 of these, 9732 were accidents
and 367 were incidents. were contributed to some sort of maintenance error.
This constituted ___% of all aviation accidents/incidents involving US registered
aircraft investigated by the NTSB for this period, see tables below.
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Table .1 Accidents/Incidents investigated by the NTSB 1983 - 1985
Table 2 Maintenance error related accidents/Incidents by category 1983-1985.
TOTAL ACCIDENTS
MAINTENANCE ERROR ACCIDENT
TOTAL INCIDENTS
MAINTENANCE ERROR INCIDENT TOTAL
91 – General Aviation
103 - Ultra light
121 – Air Carrier
133 – Rotorcraft Ext. Load
135 – Air Taxi & Commuter
137 - Agricultural
Table .3 Accidents/Incidents investigated by the NTSB 2000-2002.
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Table 4 Maintenance error related accidents/incidents by category 200-2002.
CFR14 - PART TOTAL ACCIDENTS
MAINTENANCE ERROR ACCIDENT
MAINTENANCE ERROR INCIDENT
TOTAL
91 – General Aviation
103 - Ultra light
121 – Air Carrier
133 – Rotorcraft Ext. Load
135 – Air Taxi & Commuter
137 - Agricultural
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CHAPTER V
DISCUSSION
Maintenance Resource Management (MRM) has become an umbrella term that has yet to
be clearly defined. Some current MRM programs may parallel the Crew Resource
Management (CRM) programs used for improving team communication and performance
in the cockpit. By defining resource management for maintenance and investigating
related issues, this research will develop guidelines and related training and reference
materials for MRM through extensive cooperation with the airline industry. Error
reduction is a key activity for the research program. The program seeks to develop
methodologies or techniques to proactively minimize aircraft maintenance errors and
enhance safety. General areas for research include error classification, identification,
mitigation, and reduction. Aircraft maintenance human factors research is particularly
critical for improving aviation safety.
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CHAPTER VI
CONCLUSION
To meet these challenges without sacrificing safety, individual technician responsibilities and skill levels must increase. The industry must work together to ensure that workers become more qualified and that maintenance tasks and procedures are adapted to meet human capability. Attention to human factors in aircraft maintenance will ensure not only continuing performance enhancement of the technician workforce, but also continuing flight safety.
The research program has emerged as the most significant program of its kind related to human factors in aviation maintenance. The aviation industry, the Department of Defense, national and international organizations, and governments around the world participate in the annual conference and use the products and reports that the program generates each year.
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The success of the program is based on the commitment to the application of solid scientific principles to deliver pragmatic solutions. The research shall continue to be driven by user requirements. The research shall continue to use the aviation maintenance environment as the most important daily laboratory to conceptualize, design, develop, implement, and test procedures and products to enhance human performance.
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CHAPTER VII
RECOMENDATIONSIt is important that all errors are reported, especially those which jeopardise aircraftairworthiness or cause unacceptable economic harm to the Company, so thateffective remedial action can be taken.All levels of staff must be encouraged to report all errors to their supervisor or linemanager immediately after they occur. Once the error has been reported theemployee concerned must clearly state how they wish the error to be investigatedand reviewed. If they decide to use the Engineering and Maintenance Mishap Policythis must be confirmed in writing.Once a decision has been made to use the Engineering and Maintenance MishapPolicy the supervisor (or member of management) will then collect all available datarelating to the error, i.e. details of the staff concerned, the time and date of the error,the airframe worked on, the type of error made and any other pertinent details andimmediately forward these to the Engineering Manager.
37
REFERENCES
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Shepherd, W. T. (1997). Proceedings of the Human factors and ergonomics
Society ... Annual Meeting, Santa Monica; Vol. 2; pg. 1152, 2 pgs
Shepherd, W. T., W. B. Johnson, C. G. Drury, and D. Berninger. (1991). Human
Factors in Aviation Maintenance. Phase one: Progress report. Federal
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Skormin, V. A., Gorodetski, V. I., & Popyack, L. J., Factors in aircraft accidents.
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APPENDIX A
BIBLIOGRAPHY
American Psychological Association (2001). Publication manual of the American
Psychological Association(5th ed.). Washington, DC:
N
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APPENDIX C
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