It has become a well established fact that human factors contribute immensely to major accidents that occurred in the Oil and Gas Industry over the last three and half decades. Previously, Oil and Gas drilling accidents and disaster were seen only in terms of technical failures and we always tend to neglect the human aspects. However, in recent times, through HSE and other stake holders investigations and analysis, it became clear that human factors are in most cases, a very crucial cause of the offshore oil and gas fire disasters, contributing up to 80% of major accidents, not just in the oil and gas sector but in other safety critical industries as well. [1,8]
Analysis of major accidents like Bouncefield explosions and fire in Hemel Hempstead, Hertfordshire and Piper Alpha disaster of the North Sea, east of Aberdeen clearly indicates that Engineering Safety of a large and complex system depends not only on the technical factors but also on the human/organisational, environmental and managerial factors. The synergistic effects of these factors could lead to a very serious disaster if not addressed properly, hence none of them should be neglected.
Subsequent to the Piper Alpha oil drilling platform disaster of 1998, the UK Government had to set up a public enquiry under Lord Cullen and his report was later published in 1999, a number of recommendations were made.  One significant change as a result of this is a transfer of regulatory powers from the Department of Energy (DOE) to an independent offshore division of Health and Safety Executive (HSE), Piper Alpha disaster also led to the enforcement of Offshore installations Regulations (Safety Case 1992).
In our day to day activities, It is becoming more and more evident that “human factors” is a major ingredient of efficient Safety Management system, according to the recent HSE reports, up to 80 percent of accidents in our workplace can be attributed to the actions or omissions of humans. this explains why it is important that we carefully consider human factors in safety critical industries, to help reduce accidents. 
Chau Nearkasen in his book titled “Contribution of occupational hazards and human factors in occupational injuries and their association with job, age and type of injuries in railway workers” identified causes of injuries and categorised them into six major classes, namely:
* Problems with organisation
* Lack of Job knowledge
* Environmental hazards
* Lack of know how
* Technical problems
* Human factors
A very important objective of this dissertation deals with how major Fire accidents in the Oil and Gas industry can be reduced to the lowest possible level through human factors Engineering, it starts with identifying those important human factor concern that can negatively affect safety, and proffer ways of mitigating or improving the Safety performance in the Oil and Gas industry 
1.2 PROJECT OUTLINE
This project reviews human factors how human factors have contributed to major fire and explosion accidents in the oil and gas industry in the past, it will also proffer ways of reducing hydrocarbon fire accidents through human factors Engineering.
In chapter 2, a general review of human factors, human failure and hydrocarbon fire accidents are carried out, the dissertation focuses on specific case studies to be able to determine how human factors have actually contributed to major fire disasters in the oil industry, and how they would have been averted had the necessary human factors Engineering measures been applied. Chapter 3 deals with the significance and effective application of human factors in risk management. Also discussed in chapter 3 is the use of models such as QRA, ALARP, “Model of Accident Causation using Hierarchical Influence Network” or (MACHINE), Fault Tree etc as tools for reducing accidents through risk management.
The case studies specifically looks at different major oil and Gas fire disasters that happened over the years, why they happened, the human factors perspective and all other observations.
Findings from the analysis are discussed in chapter six
The following methods are discussed under Safety improvement through human factors:
* Commitment and Leadership
* Safety Culture
* Design improvement
* Change management
* Safety training
* Involvement of HSE and ALARP Concept
Recommendations are made for further research studies
1.3 PROJECT AIMS AND OBJECTIVES
The key aims and objectives of this dissertation are as follows:
* To critically review how human factors can contribute to major fire and explosion accidents in the oil and gas sector
1.4 Scope and Methodology:
Considering the extent of information available within causes of accidents in the oil and gas industry, the scope of this project was deliberately directed to the human factors, the background study of this dissertation was based on the review of similar works carried out on human factors in other high hazard industries such as nuclear, mining, construction and aviation industries.
Although similar works have been carried out in some of these high hazardous industries mentioned above, none (to the best of my knowledge) has been carried out with respect to fire and explosion in the oil and gas industry, the study was limited to human factors contribution to oil and gas fire and explosions accidents and does not explore in details, other factors such as Technological malfunctions and environmental elements which can also lead to major accidents, it was also directed specifically to Fire and explosion accidents, because among all the major accidents that occur in the oil and gas industry, hazards posed by fire and explosion appears to be the most critical in terms of number of fatalities and financial consequences sustained from these accidents. Human factor elements was also reviewed and analysed. Case study of offshore fire accidents in the oil industry was also reviewed and lessons learnt was also highlighted.
The project also considered key elements for safety management and improvement in details, application of human factors in safety management system and application of human factors Engineering in Oil and Gas Engineering safety.
In the compilation of this report, articles, journals and publications on safety Engineering, accident investigations and Ergonomics from HSE and past dissertation reports were used. Some of the information relating to Human Factors, fire and explosions and major accidents were also collected through Elsevier, Scopus and, Science direct. There was also an extensive use of ‘Google' search engine in order to get some other relevant information that are publicly available.
Case studies that were used in this review include: Piper Alpha Fire Disaster of Northsea, Ocean Odyssey of Northsea, West Vanguard semi submersible of Norway, Mumbai (Bombay) High North Platform operated by and Usumacinta Jack-Up platform of the Gulf of Mexico operated by PEMEX.
2.0 LITERATURE REVIEW
2.1 CONCEPT OF HUMAN FACTORS:
There are lots of definition on human factors, according to Health and Safety Executive, Human factors can be defined as organisational, job, environmental factors as well as human and individual characteristics which influence the behaviour at work in a way which can affect health and safety. It deals with all aspects of life including psychological, physical, social, biological and safety attributes of a user and the system the user is in.[10,13]
A detailed definition was given by Sanders and McCormick in their book titled “Human factors in Engineering and design” They stated that
“Human factors discovers and applies information about human behaviour abilities, limitations and other characteristics to the design of tools, machines, systems, tasks, jobs and environment, for productive, safe comfortable and effective human use”.
Human factors is a unique and scientific discipline that deals with comprehension of interactions among humans and other components that make up a system. It is aimed at application of scientific theories and principles to Engineering design with the primary objective of achieving human safety and enhancing system performance. 
Human factors can be broadly classified into the following;
* Ergonomics: Scientific study of human potentialities and limitations in machines, work environments, work processes and system design
* Cognitive psychology: This deals with human behaviour with respect to the internal mental processes, such as perception and information processing that controls the human body.
* Anthropometrics: This has to do with human body statistical data collection, measurements of human body in a population for product design optimisation.
Various aspects of human factors and how they interact with one another is described in the diagram below.
GENERAL DIMENSIONS OF HUMAN FACTORS
Human factors is to a large extent used synonymously with ergonomics, the two words may have different origins but they are basically the same in terms of technical areas they cover, the distinction that often occur lies in the use of words or semantics
It is very important to always identify the limitations in human-machine interaction of any system
In Engineering design, the aim of the designers should be to apply understanding of how humans interact with machines, not just physically but also psychologically, in order to achieve that, the product and end user should be at the forefront of every decision making , this is generally known today as “user centred design.”
It is very essential to engage Human factors and Safety Engineers at the early or design stage of a project in order to achieve maximum risk reduction right from the onset.
2.2 LEVELS AND ELEMENTS OF HUMAN FACTORS
There are three aspects or interrelated dimensions that will always come to mind anytime we discuss human factors; According to Hetherington et al , elements of human factors elements are grouped into; personal or individual, Job or design issues as well as organisational or management issues
According to the questionnaire survey of UK personnel in the North Sea carried out by Flin and Mearns  (Hetherington et al 2006), they identified three key factors which could contribute to accidents and near misses in the Oil and Gas industry
(1) Individual attributes (including competence, skills, experience, personality, knowledge, attitudes to safety, risk perception, etc)
(2) Job characteristic (work task, environment, display and controls, job stress, procedures, etc), and
(3) Organisation or Platform characteristics (social support, communications, leadership, work patterns, safety culture and safety management systems)
Analysis of the study also showed that factors such as employee job satisfaction, management attitude towards to safety, management attitudes to safety versus production and work condition exerts the greatest influence on workers' risk perception and their degree of satisfaction with the current safety measures.
The Job: This includes the individual or work load, the environment where people work, procedures, job roles, nature of the given task, controls and displays design. It is important to note that tasks should be designed in accordance with fundamental ergonomic principles, it will also take into considerations, human capabilities and limitations. Mismatch between human capabilities and job requirements either through improper design of the workplace and working environment (Physical mismatch) or improper individual's information and decision-making can possibly lead to human error, therefore Jobs must be properly matched with humans to reduce overload and increase efficiency.
The Individual: This includes the individual attributes such as skills, risk perception, competence, personality, habits, and other individual characteristics which people bring to their job, which can either positively or negatively affect behaviour in a variety of ways.  Some individual attributes like personality cannot be changed, they are constant, however other attributes like skills, competence, attitudes can be enhanced.
The Organisation: This includes workplace culture, patterns, and communication methods, management and leadership, these factors are oftentimes neglected but they can be very influential to an individual or group in a work place, as a matter of fact, Organisational factors exerts the greatest influence on the behaviour of an individual or a group , hence it is very important for every organisation to set up their own positive health and safety culture which will be aimed at promoting employee's dedication and involvement at all levels, acknowledging the fact that deviation from established health and safety standards is not acceptable.
It is also important to note that for human factors intervention to be effective, these key aspects will be considered as a whole and not in isolation.
workload, duration, frequency, critical nature, interaction with other tasks, physical memory, vigilance, attention
Procedures and Instructions
clarity, accuracy, ease of use, applicability, sufficiency, revision, format, meaning
control of environment, temperature, noisy and unpleasant working condition, work space, humidity, vibration, restriction of movement, lighting
Displays and Controls
identification, compatibility, distinctiveness, reliability, readability, ease of operation
Time pressure, distractions, work load, fatigue, high risk environment, isolation, monotony
Training and Experience, risk perception, capabilities, skills and knowledge, personality, attitudes, motivation
Work hours, communication, attitude to safety, manning, availability of resources, roles and responsibilities, team structure, rewards and benefits
The table shows the list of performance influencing factors drawn from a wide variety of sources: Redrawn after Redmill 
Human Factors Engineering: This is the application of human limitations or potentialities (cognitive or physical) to projects and system design, this can be applied to all stages of systems with human interface, human factors Engineering is concerned with the application of facts and s that are already known about the potentials and limitations of humans to the Engineering designs of systems, processes, facilities and products, it involves the understanding of human attributes to achieve a better human machine adaptability and compatibility in a way that ensures safety, productivity and better performance. 
Over the years, a lot of accidents that occurred in the oil and gas industry have been attributed to human factors, (human or operator failures). It is important to also acknowledge the fact that in these many cases of accidents, causes of human failure occur as a direct consequence of poorly designed human machine interfaces. . It is the objective of human factors engineering to ensure that design induced human errors is greatly minimised through application of proper safety engineering principles
Some years back, most human/machine engineering systems have been designed without considering the safety implications for the operators and maintainers, a more pragmatic and efficient approach to human factors application now helps to ensure that humans are considered to a large extent as integral part of the system.
Most Engineering systems require human operators and or human maintainers, It has also been discovered that human machine systems designed with humans as the key elements perform better than those that are not. Therefore, good application of human factors engineering design criteria during the development of complex engineering systems is very important in order to ensure that the system continues to perform optimally.
This form of Engineering can be applied to Engineering design of all systems with human interface, this helps to improve system performance and reduce operational errors, it's application also helps to increase system reliability, ease of use, aesthetic appearance, user acceptance, and productivity
Other objectives of human factors engineering in a workplace include reduction of operator fatigue, stress, product liability, loss of time and failure of equipments. Simply put, human factors engineering is the only engineering discipline that studies interaction between humans and machines. Objectives of human factors Engineering can only be achieved by proper identification and understanding of the limitations of the human machine interaction within a given system and augment, the following approaches can be used to implement solution and offset any deficiency.
· Equipment/System Design: Physical equipment which humans use to work can be changed or modified, if it has been discovered that it is no longer safe for use or no longer performing optimally.
· Environmental Design: environmental conditions such as temperature, pressure, noise can be changed within a given system in order to promote better human machine interaction.
· Task Design: Sometimes, it may not be necessary to change the design of equipment or working environment, but by changing what operators do or the way they do it, greater efficiency can be achieved.
· Proper Training and Selection: Another way of achieving human factors objective is through proper training and practising, this can be achieved through drills, it is particularly helpful during emergencies like fire, this also recognises the fact that different individuals have different performance levels for different tasks, hence performance can be optimised by assigning different tasks to individuals that possesses the best skills for the specific task.
The diagram below illustrates the human-machine compatibility approach and the various interactions. 
- Matching of compatibility relationships
Human - Machine Compatibility approach to Human Factors
2.3 HUMAN ERROR
Oftentimes in the industry, people interchange human factors with human errors, they are often regarded as two words that mean the same thing, this proposition or idea is wrong, although human factors and human errors are related, they mean different things.
While human factors deal with how humans interact with machines and the effects this interactions have on safety, human failure simply means inability of man through acts of omissions and commissions by man which have been found to deviate from the standard or generally acceptable principles, these acts are not objective and contribute to accidents either directly or indirectly.
Over the last two decades, we have discovered a lot about why people fail, and we have now learnt that accidents are not just as a direct consequence of human failure, which is beyond managers or supervisors control, this has always been the general belief and it's no longer acceptable.
Humans are susceptible to errors no matter how knowledgeable, trained or experienced we are, sometimes it occurs indirectly through the systems we use and the challenge is to set up an error free system that will completely eliminate errors, at other times, failures may crop up from other people that are not directly involved with the ongoing maintenance and operations of the project, it may be hidden for a long time until they are triggered.
In the past, when accidents occur, companies usually formulate policies and disciplinary measures aimed at reprimanding the employee, these measures may include more supervision and staff training to make sure that it doesn't happen again. Sometimes it may involve making more investments in technology in order to automate the operations and keep humans out of the loop. While these measures are good, we often times neglect the fact that human factors is a distinct element that must be recognised and managed efficiently in order to reduce risks to acceptable level. 
While these company approaches may appear adequate immediately after the accident have occurred, they are usually unsustainable in the long run. According to James Reason of Manchester University,  human errors have two perspectives, the person approach and the system approach, the person approach deals with the individual's errors, weaknesses, and other inadequacies, the system approach focuses more on the individual's work conditions and fashion out ways to either avert or mitigate effects of any error that might occur.
The fundamental principle of system approach is based on the fact that humans are fallible, therefore no matter what we do, errors are bound to occur even in the most safety conscious organisations, this approach sees errors as something that originated from the work system and not just from human inadequacies, corrective measures is based on the fact that we can make human working conditions better even if we can't change the individual human attributes, this approach focuses more on the how and why an event occurred instead of who caused it.
On the other hand, person approach is primarily concerned with acts of omission and commission, violations of procedures of people, this can be clearly seen in major accidents such as piper alpha.
This approach portrays these human acts of omission and commission as something that results from human carelessness, negligence or recklessness of man, it views people as individuals that are free to choose between right and wrong, safe acts or unsafe acts, if anything goes wrong, then the individual is to blame for not doing it right, a major shortcoming of this approach is that by focusing our attention on a person as the cause of error, the achievement of safety and greater efficiency is impeded since this approach does not completely remove major cause of errors from the system .
It is necessary to note that human failures doesn't just occur randomly, they follow different patterns which are attributed to different causes, as a result, various methods of reducing and preventing them are also different.
Categories of Human failure
Human failures can generally be categorised into three: errors, mistakes and violations, this can generally be broadly classified into intentional and unintentional errors
· Slips and Lapses: These are acts of omissions or commission which were not deliberate, they include slips and lapses. Slips are failure to carry out a particular task, for instance typing the wrong key or pushing the wrong knob, sometimes it might involve doing the right thing but not taking or following procedures for instance pushing the right knob but to the wrong direction. Lapses is said to occur when we fail or forget to do what we had in mind, use of reminders is a great way to minimise lapses, however the best way to void both types of errors is by designing it out of the system. They are generally referred to as skill based errors. 
· Mistakes: these are also unintentional errors that occur when planned actions being executed are wrong, in other words it occurs when we are doing the wrong thing believing they are right, they are usually errors resulting from poor judgement. Mistakes can be avoided or eliminated through training, simple mistakes can result to serious disasters causing personnel injuries and equipment damages, hence training is important, Mistakes are grouped into two:
ü Rule based mistakes: This occurs when our behaviour is based on stored rules, instructions or procedures usually in this form of if then statement: “if <condition> then <diagnose>” or “if <condition> then <take action>” . This usually occurs as a result of application of familiar skills or knowledge we are comfortable with even when they are not most efficient.
ü Knowledge based mistakes: This involves conscious application of plans and strategies to an unfamiliar circumstances rather than use of already existing rules in order to achieve a particular desired goal, by so doing miscalculations and misdiagnosis are bound to occur resulting to what is known as knowledge based mistakes.
· Violations (Breaking the rules): These are intentional infringements, non compliance or deviations from rules instructions or procedures.  Infringement of health and safety regulations has been found to be the cause of several accidents in oil and gas industry, there are several reasons why people break rules in the industry, part of which is the desire to complete a task within the deadline no matter the prevailing circumstances, violations is subdivided into four as illustrated below: Routine violations, situational violations, exceptional violations, or malicious acts
ü Routine violation is said to occur when people break the rules, instructions or procedures and take it as a normal way of life within the work group. In some cases this can be as a result of wrong perception that the rules no longer apply or that the laws are not longer being enforced, people also violate rules in order to cut corners or costs to save money and time.
ü Situational Violation: This is when people break rules due to the situation on ground, for instance pressure from job, extreme weather conditions, in such case, it may be difficult to comply with rules in that particular circumstances, with the necessary risk assessments, the possibilities of such violations could easily be identified at the onset through proper risk assessments.
ü Exceptional Violations: These are very rare and it occurs in exceptional, emergency or extraordinary circumstances when something has gone wrong, a typical example is the case of piper alpha disaster when people had to violate the rules by jumping into the ocean because of the fire. Training and preparations for emergency situations is necessary in order to minimise exceptional violations.
ü Acts of Sabotage: This is self explanatory, just as the name implies, it can be as a result of vandalism or direct act of terrorism by a de-motivated employee.
Violations can be managed through several ways, one of which is by ensuring that regulations and procedures are feasible and explaining the reasons behind certain rules and regulations, workforce should also be involved in drafting these rules to increase the acceptance identifying the root cause of any violation helps to prevent future occurrence.
Types of human Failure
Redrawn after HSE Oct, 2005 
Causes of Human Error
Engineers and scientists have asked series of questions as regards why people fail, a lot of propositions and formulations have been formulated over the years. Series of error paradigms have been proposed. The four major error paradigms are discussed below.
ENGINEERING OR DESIGN ERROR PARADIGM
This deals with Engineering or Technical aspects of an engineering system. A unique characteristics of Engineering errors and failures associated with it lies on the fact that these errors are indeed completely avoidable but because of the unreliability of the human component within the human machine system, they always occur while some engineers, scientists and psychologists have suggested that the best way to completely eradicate this type of error is to completely remove the “human factor” component from a system by Engineering it out through automation, others suggest the idea of improving human reliability through better and more reliable design. 
It is no longer a subject of controversy that proper acknowledgement of human failures plays a very important role in the design of error free engineering system or component and that all safe, successful design comes from acknowledgement of those key areas that might go wrong. 
This is where Safety and Reliability Engineers are needed not just to ensure that safety critical elements behave as required but also to analyse the design of an engineering at an early stage and determine when and where failures are likely to occur, safety standards and requirements also provided if necessary, in order to ensure integrity.
Various probabilistic analysis are engaged to determine what can go wrong and when.
Automation: The proposition here is that designing human factors out of the systems through automation is a good or viable means of risk reduction. For instance an unmanned helicopter flying into the north sea or hazardous installation elsewhere will have risk reduced to a very low level.
In her book titled ironies of automation, Brainbridge stated the following 
· “The designer has more opportunity to introduce errors into the system during the design process.
· The operator still has to do those tasks which the designer has not been able to automate.
· The operator's role is changed to one of the supervisory monitoring of an automated system, but with reduced information about the system itself (humans are generally poor at monitoring tasks that require extended periods of vigilance)
· The operator may become deskilled and yet be expected to intervene when the automated system fails”.
Those that propose this idea believe that because high percentage of accidents are attributed to human factors, therefore errors can be eliminated by designing the human component out of the system, however another school of thought doesn't agree with this, instead they propose what is known as “human machine interface design”
Human Machine Interface Design:
The view here is that human errors occur as a result of mismatch between the human capability task demand and general characteristics of machine interface provided. 
This view recognises the fact that humans are not reliable, therefore it tries to proffer solution that will bring down risks to minimal level through changes in ergonomic design, job aids provision and training, according to Lutzhohft and Dekker , this paradigm is of the view that system automation brings about new weaknesses and magnifies existing ones. So much relying on engineering system reduces human situation awareness of the engineering system.
Currently In offshore oil and gas industry, safety critical systems such as vent relief valves, emergency shutdown (ESD) and venting valves (ESV), fire gas protection systems are now automated. The operator then relies on these automated systems which in turn influences his or her level of risk perception and reduces situation awareness, this can cause serious problems, a typical example is the BP Texas refinery accident where the operator was heavily relying on the automated system and was unable to observe that the indicator valve has failed. 
INDIVIDUAL ERROR PARADIGM
This deals with personality characteristics or traits of an individual as they relate to safety and accidents, different people have different perceptions and attitudes towards safety. This is generally divided into two:
(i) Traditional Safety Model: The way people traditionally view human error is directly connected to negligence and blame, people generally believe that errors are caused by a person that is not hardworking or has not put in serious effort, hence the view that all accidents are as a result of unsafe acts as opposed to unsafe conditions [Heinrich 50, Peterson 75] 
(ii) Risk Perception and Safety Culture: Different people have different risk perceptions, the view here is that acts and behaviours resulting to violation of rules and procedures can be attributed to human motivational causes which is in turn influenced by human attitudes, perception and beliefs (safety culture)
JOB ERROR PARADIGM
The view here is that human errors occur as a result of mismatch or imbalance between humans and job, i.e. errors occur when humans are incapable to handle the demands of a job either physically or mentally, errors can therefore be reduced by identifying the root cause of the error.
ORGANISATIONAL ERROR PARADIGM
The idea here is that human errors which causes accidents arise from certain organisational preconditions in the workplace, these include improper allocation of responsibilities and poorly designed job conditions, time pressure, low morale, low motivations and inadequate training within an organisation as illustrated in the diagram below.
Accident is an unforeseen, unexpected and unintentional action or event occurring at a particular place and at a particular time, it is usually characterised by negative probabilistic outcome, which would have otherwise been mitigated or completely avoided had the events leading to the accidents been acknowledged on time and acted upon. 
It is an undesired situation which brings about injury or damage to the humans, plant or environment, this should not be confused with incident which is an undesired situation with potential to cause accident . Accidents can be broadly grouped: injury and non-injury accidents,
Injury accidents are accidents resulting to injury while non-injury accidents are accidents that doesn't involve any personal injury but may include things like property damage or environmental degradation. When one or more deaths result from accidents, it is referred to as fatality.
Some common accidents can be deterministically predicted, identified, investigated, analysed and documented, this is referred to as root cause analysis and will be discussed in details later in this chapter. However, It should be noted that there are some accidents that cannot be predicted or identified, they are usually random and uncommon and will always occur, they cannot be deterministically predicted.
From the study conducted by the Health and safety executive (HSE), it was found that up to 80% of major accidents in industries are attributed to human factors, this buttresses the fact that humans exerts a considerable degree of influence in the general safety and reliability of safety critical systems. This is primarily because humans are involved in all the various stages of plant cycle ranging from design and construction to operations, maintenance and of course decommissioning.
2.4.1 CAUSES OF ACCIDENTS:
Causes of accidents can be studied at two different levels: micro or near miss level and macro or disaster level for two major reasons.
Near miss is an unplanned situation or event which had the potential to cause an injury or inflict a damage but did not eventually give rise to that. It is important that we study and report accidents causation at this level in order to prevent future reoccurrence and improve the effectiveness of the company.
At the disaster level, incidents such as the piper Alpha fire disaster of the North Sea can put a company out of business, the repercussions of such an event is something that will always be associated with the company till the end of it's life, such disaster usually gives rise to a major change in legislation, there is also associated general increase in cost in the sector as clearly seen in the case of Piper A. hence it is very imperative that we study them.  Causes of accidents are generally grouped into basic causes, underlying causes and immediate cases.
An organizing framework for human factors which contribute to organizational accidents in adapted from Stanton (1996), Jorgensen (2002), and HSE (1997). Redrawn after Hetherington et al .
Framework of the relationship between underlying causes of accidents (human factors) and their immediate causes (human errors) Redrawn after Gordon 
Contribution of humans to Accidents:
Humans can contribute to accidents in a variety of ways
(a) Initiation: All accidents have initiating event which is the primary event that can result to accident conditions, the resulting accident could be from a direct or indirect failure, direct failures usually results to immediate effects, however consequences of indirect failures may not be noticed immediately. One thing is common, whether the accident is as a result of direct failure or indirect failure, there is always an initiating event. Through human failures, accidents can occur, although humans tend not to deliberately fail, we tend to make these errors either by the way we think or process information, training, or the way our equipments are designed as well as the organisational culture we work in.
(b) Escalation: Human decision can mitigate or escalate the outcome of an incident, we can make disastrous decisions even when we know the consequences, humans can also misconstrue or misunderstand a particular circumstances and act inappropriately, if wrong decisions are made, the outcome could be disastrous, however if right decisions are made, the potential disasters could be mitigated. For instance, if a major accident such as fire or explosion is initiated, either by man or any other means, and they are not properly controlled, it could escalate, ie become more intense.
(c) Emergency Evacuation: In the event of escalation, loss of lives and properties can be greatly reduced by proper emergency response, training and drills are very essential. Response or rescue operations should be both effective and fast, particularly during high risk operations in remote areas like offshore oil and gas drilling operations.
When considering human failures and how they lead to accident, two kinds of failures can be involved:
Active failures: are failures whose effects or consequences are almost immediate, they are usually made by operators at the frontline such as machine operators and control room staff and can include such things as deviating from procedures, this can result to failure of safety critical elements or increase in their probability of failure. In circumstances where there is no room for any form of error, this kind of failure can greatly impact on health and safety. Often this kind of failure can be prevented by redesign of the machinery, modification of the operating systems or training. [6,8,10]
Latent Failures: These are more of organisational “safety culture” within a particular organisation, these are usually committed by maintenance staff, construction workers, inspectors, and high level decision makers, they are characterised by adverse effect that may lie dormant for a very long time, only to become evident when they go into combination with other elements to break the systems defences as illustrated in the diagram below.
General Accident Scenario, Redrawn after Redmill 
Latent failures can seriously impact on human reliability, these kind of failures are caused by those who are removed from direct control interface, this group of people influence the design of equipments and systems and generally determine how to do things in an organisation. Generally speaking, latent failures are failures occurring in the Health and safety management systems of an organisation. 
HSE Accident Model:
Performance Influencing Factors
Redrawn after HSE 
Hydrocarbon Fire and Explosion
Fire is the rapid oxidation of a combustible material releasing heat, light, and various reaction products such as carbon dioxide and water. 
For a Fire accident to occur, the three basic elements must be present: a source of oxygen (air), a source of fuel, and a source of heat (ignition), these fundamental elements are shown in the fire triangle below.
FUEL OXYGEN (Air)
By isolating either the fuel source, removal of the oxygen or heat, hydrocarbon fires can be extinguished.
Fire Accidents and Causation
The significance of hazard associated with fire accidents can not be over emphasised, on the average, approximately 300 lives are lost per year with the estimated damage of about £1000 in the UK alone due to fire accidents. In the Oil and Gas Industry, fire and explosion is the second largest contributor of accidents resulting to about 18% of all the major incidents as shown in the chart below. Apart from it being one of the largest contributors, it is usually very catastrophic resulting to damage to properties and human life.
Significant Incidents by Category 1998-2002 Oil and Gas Industry.
Redrawn after Attwood et al 
Recent fire disasters in safety critical industries like oil and gas have shown the importance and severity of the consequences of a major fire accident in a site or a given situation, in a good number of cases, these fire and explosion accidents have either directly or indirectly given rise to either changes in existing legislation or introduction of fresh fire legislation. 
One notable incident that brought about a change in legislation is Piper Alpha Platform of North Sea in 1988 in which 167 people were killed, the accident brought about the introduction of what is now known today as “safety case” requirements for all installations that are offshore, this requires the operator of an offshore installation to compile a large report that described each installation, the installation and drilling processes, identified the hazards associated with these activities, analysed the associated risks and have taken necessary measures to reduce those risks to the level that is as low as reasonably practicable. (ALARP). It also led to shift or transfer of responsibility from the department of energy (DOE) who regulated the offshore health and safety during the 70's to an independent Health and Safety Executive (HSE). It eventually led to the introduction of Prevention of Fire and Explosion Evacuation Regulations (PFEER) in 1995.