When Special Cause Variation Becomes Common Cause Variation

When Special Cause Variation Becomes Common Cause Variation

By OffRoadPilots

A safety management system (SMS) operates in a risk management environment

where associated hazards are assessed, classified, and accepted or rejected by the

accountable executive (AE). There are several inherent risks in aviation, triggered

by special cause variations or common cause variations.

Inherent risks triggered by common cause variations and are systems required for

processes to work as intended, and they are beyond management and control of

airport or airline operators.

Adverse weather conditions such as thunderstorms, turbulence, fog, and strong

winds can pose significant risks to flight safety.

Despite rigorous maintenance checks, mechanical failures or malfunctions in

aircraft systems can occur, leading to potential safety issues.

Collisions between aircraft and birds or other wildlife can pose a threat to aviation

safety, potentially damaging the aircraft and compromising its ability to fly.

Incidents where an aircraft, vehicle, or person enters the protected area of an

active runway can lead to collisions or runway accidents.

Miscommunications in air traffic control instructions can result in conflicts

between aircraft and compromise safety.

Insufficient fuel, fuel contamination, or other fuel-related problems can lead to

engine failure and emergency situations.

Fatigue among pilots can impair judgment, reaction times, and overall

performance, increasing the risk of accidents.Issues with navigation equipment or errors in navigation can result in aircraftdeviating from intended flight paths.

In-flight medical emergencies can occur, affecting both passengers and crew

members and requiring prompt and appropriate response. 

Mitigation of inherited risks

include identifying and

integrate common cause

variation in operational

training programs. Special

cause variations are

deviations from processes

and are not an integrated part

of the process for the process

to function as expected. However, special cause variations may intentionally or

unintentionally be accepted by the AE as common cause variations and integrated in the process for the process to function as expected.

Mitigating a hazard is to place a process under construction.

The Swiss Cheese Model is a metaphor used in risk management and safety

analysis to illustrate how multiple layers of defense, each with its own weaknesses,

can still collectively prevent errors or failures.

The model visualizes defense layers as slices of Swiss cheese, where each slice

represents a barrier or safeguard against a potential error. The principle is founded

on that no single slice is perfect, and each may have holes or weaknesses. When

these holes align across multiple layers, they create a pathway for an error to pass

through all the defenses, leading to a failure or adverse event.

The key idea is that by having multiple layers of defense with different strengths

and weaknesses, the overall system becomes more robust and resilient. The Swiss

Cheese Model highlights the importance of addressing vulnerabilities at various

levels to enhance the overall safety and reliability of a system.The holes in the Swiss cheese are formed during the cheese-making process and is

the results of external elements and active hazards are introduced used in the

process as common cause variations.

The holes in Swiss cheese, also known as eyes, are formed during the cheese-

making process. As the cheese ferments, carbon dioxide gas is produced by the

bacteria, and these gas bubbles create the characteristic holes in the cheese. At

first glance it appears that holes in the Swiss cheese are randomly formed. The

process is somewhat controlled but not precisely structured, leading to a unique

pattern of holes in each batch of Swiss cheese.

The size and distribution of the holes depend on factors like the type of bacteria

used, the temperature, and the duration of fermentation. The Swiss cheese model

used as a metaphor to explain what, when, where, why, who and how accidents

occur have one thing in common with occurrences, that they also are somewhat

controlled but not precisely structured.

The reason the holes line up in a Swiss cheese is related to how the cheese is

processed, it is related to the point of view of the observer, and it is related to how

the cheese is sliced. These three principles also apply to pre-accident events of

occurrences and how special cause variations are be floating within the process to

a convergent point where they line up with other special cause variations, or

common cause variations.

A common cause variation for air navigation without using navaids is that upper

winds move an aircraft away from the desired track. Pilots make estimated

corrections for this by selecting a heading into the wind that is left or right or

desired track to remain as close as practical to the planned track. By random

chance there is an inconceivable likelihood that two aircraft will be at the same

intersecting location at the same time.With the introduction of global positioning system (GPS) air navigation became precision navigation. GPS is a special cause variation since GPS is not required for an air navigation process output. Some years ago, two aircraft were navigating by

visual flight rules (VFR) using GPS, both aircraft were on a precision course near St.

Brieux and collided midair. The likelihood for two aircraft navigating VFR would be

at the same time (speed), space (location), and compass (direction) is

inconceivable, and times between intervals are imaginary, theoretical, virtual, or

fictional.

A common cause variation is

the migratory bird season.

When the migratory bird

common cause variation

converges with a special

cause variation, such as a

student pilot performing flight

training maneuvers over

fields, lakes or rivers, the

likelihood for an occurrence is

systematically, and times

between intervals are

methodical, planned, and dependable, without defining the operational system or

processes involved.

Special cause variations become common cause variations when there is drift in

processes by acceptable work practices, overcontrolling, or decisions made by the

accountable executive.

DRIFT

Process drift refers to the gradual and unnoticed changes that occur in a system or

process over time. It can lead to deviations from the intended or expected

performance of the system. Process drift affect airport and airlines safetymanagement system, and it is crucial to monitor and manage drift for processes to

remain on a path without deviations and continues to meet its objectives.

Pilots are required to follow specific checklists before, during, and after flights.

Process drift may occur if pilots start skipping certain checklist items or perform

them in a different order over time, leading to oversights and increased risks.

Effective communication is crucial in aviation. Process drift can occur if air traffic

controllers or flight crews deviate from established communication protocols. For

instance, using non-standard phraseology or not adhering to the correct radio

frequency can compromise communication and lead to misunderstandings.

Maintenance crews follow strict procedures when inspecting and repairing aircraft.

Process drift in this context may involve technicians deviating from the

recommended maintenance practices, potentially leading to undetected issues or

improperly repaired components.

Crew Resource Management (CRM) is a set of training and communication skills

designed to enhance teamwork within the cockpit. Process drift in CRM may

manifest as a gradual breakdown in effective communication and coordination

among flight crew members, impacting decision-making and increasing the

likelihood of errors.

Pilots rely on accurate and timely weather briefings to make informed decisions

about flight routes and conditions. Process drift may occur if flight crews start

neglecting thorough weather briefings, leading to unexpected weather-related

challenges during the flight.

To mitigate process drift in aviation safety, industry stakeholders, including

regulatory bodies, airports, airlines, and training organizations, emphasize the

importance of regular training, audits, and adherence to standardized operating

procedures. Continuous monitoring and feedback systems are essential to identify

and correct any deviations from established processes, ensuring a consistent andhigh level of safety within the aviation industry. Correcting deviations may include

a correction to the process, or it may include a correction of human factors,

organizational factors, supervision factors, or environmental factors. However,

process drift is neither bad nor good but is neutral. What is learned from drift may

be implemented in the process to achieve an acceptable performance outcome, or

it may be discarded as a process hazard.

ACCEPTABLE WORK PRACTICES

Acceptable work practices in

aviation safety are crucial to

ensure the well-being of

passengers, crew, and the

overall safety of air travel.

These practices encompass a

wide range of activities and

procedures that adhere to

industry standards and

regulations.

Pilots and aircrew must adhere

to aviation regulations set by

aviation authorities. This

includes following guidelines on

flight hours, rest periods, and crew qualifications.

Aircraft maintenance personnel must strictly adhere to scheduled maintenance

procedures and inspections outlined by the manufacturer and regulatory bodies.

This ensures that the aircraft is in optimal condition and reduces the risk of

mechanical failures.

Flight crews and ground personnel must undergo regular training on emergency

response procedures. This includes handling situations like engine failures, fireemergencies, or medical incidents on board. Training ensures a quick and

coordinated response to unexpected events.

Clear and concise communication is vital in aviation. Pilots and air traffic

controllers must follow established communication protocols to avoid

misunderstandings and ensure safe coordination during takeoff, landing, and in-

flight.

Pilots must consider weather conditions when planning flights. Acceptable

practices include obtaining up-to-date weather information, assessing its impact

on the flight, and making informed decisions, such as diverting to an alternate

airport if weather conditions deteriorate.

Aviation professionals engage in ongoing training and education to stay updated

on the latest safety practices, technological advancements, and regulatory

changes. This ensures that they are well-equipped to handle evolving challenges in

the aviation industry.

Accurate record-keeping is essential for tracking maintenance activities,

inspections, and operational details. Proper documentation helps authorities

monitor compliance with safety regulations and provides a historical record for

analysis and improvement.

By adhering to these acceptable work practices, the aviation industry strives to

maintain a high level of safety and mitigate potential risks associated with air

travel.

OVERCONTROLLING

In aviation safety, overcontrolling processes refer to situations where excessive

regulations, strict procedures, or micromanagement may inadvertently hinder

overall safety rather than enhance it. While regulations and procedures are crucial

for maintaining regulatory compliance, an overly restrictive or bureaucratic

approach can lead to unintended consequences.Overemphasis on extensive documentation and paperwork can divert valuable resources away from actual safety measures. Pilots and maintenance crews may spend more time on administrative tasks than on addressing immediate safety concerns.

If procedures are too rigid and

do not allow for flexibility in

response to special cause

variations, it can impede the

ability of flight crews to make

timely decisions in the

interest of safety. For

example, if a pilot is strictly

bound by procedures and

cannot deviate what they

view as an emergency, it

compromises the ability to

respond effectively.

Excessive oversight and micromanagement from regulatory bodies or management can create a culture of fear and discourage open communication.

This may lead to underreporting of safety concerns by frontline personnel, as they

may fear punitive actions.

Overly prescriptive training programs that focus solely on compliance rather than

cultivating critical thinking skills can result in pilots and other aviation professionals

being ill-equipped to handle unexpected situations.

A bureaucratic approval process for implementing safety improvements may cause

delays in the adoption of new technologies or procedures that could enhance

safety. This delay could expose the aviation industry to unnecessary risks.Balancing a robust safety framework with operational flexibility is crucial to

ensuring that overcontrolling processes do not compromise aviation safety.

Striking the right balance allows for adherence to essential safety standards while

enabling quick and effective responses to dynamic and unforeseen challenges in

the aviation environment.

DECISIONMAKING PROCESS

In aviation safety, decision-making processes play a critical role in ensuring the

well-being of passengers, crew, and the aircraft. There are established frameworks

and protocols that guide decision-making at various levels within the aviation

industry.

Pilots use ADM to assess the situation, identify potential risks, and make informed

decisions. For example, if a pilot encounters unexpected weather conditions, they

may decide to divert to an alternate airport.

Crew Resource Management (CRM) This involves effective communication and

collaboration among the flight crew. An example is when the crew identifies a

discrepancy in instrument readings, they collaborate to troubleshoot and decide

on appropriate corrective actions.

Air Traffic Control (ATC) Decision Making are routing and sequencing. ATC makes

decisions on aircraft routing and sequencing to ensure safe and efficient air traffic

flow. If there's congestion at an airport, ATC might reroute incoming flights or

adjust departure schedules.

ATC may alter flight paths or ground operations in response to adverse weather

conditions. For instance, during a thunderstorm, ATC might implement holding

patterns or ground stops to avoid hazardous conditions.

Maintenance crews may have to decide whether to defer certain non-critical

repairs to avoid delaying a flight. They consider factors such as the aircraft's overall

safety and operational requirements.When faced with a malfunction in a critical system, maintenance personnel need to decide whether the aircraft is airworthy or if it requires grounding for repairs.

Regulatory Decision Making are compliance decisions. Aviation authorities make

decisions related to regulatory compliance. For example, the decision to update

regulations governing flight crew duty hours in response to new data, information,

knowledge and comprehension of systems.

Regulatory bodies may issue airworthiness directives requiring operators to

perform specific maintenance actions or modifications based on safety concerns or

identified issues.

Pilots, air traffic controllers and airport operators may have to make sound

emergency decisions during in-flight emergencies or at an airport due to special

cause variations. These decisions aim to ensure the safety of the aircraft and its

occupants.

In all these cases, the decision-making processes involve assessing available data,

information, knowledge, and comprehension when considering safety implications,

and selecting the most appropriate course of action. Training, experience, and

adherence to established protocols are crucial elements in the effective decision-

making processes within the aviation industry.

CRITICAL THINKING

Critical thinking in aviation is crucial for ensuring safety, efficiency, and effective

decision-making in a complex and dynamic environment. Aviation professionals,

including pilots, air traffic controllers, and maintenance personnel, rely on critical

thinking skills to assess situations, identify potential risks, and make informed

decisions.

A pilot encounters unexpected weather changes during a flight. Critical thinking

involves assessing the current weather conditions, understanding the potentialimpact on the flight path, and making decisions to ensure the safety of the

passengers and crew.

An air traffic controller must

decide on the sequencing and

spacing of incoming and

outgoing flights. Critical

thinking is essential for

considering various factors,

such as weather conditions,

aircraft performance, and air

traffic density, to make

decisions that prevent

collisions and ensure efficient

traffic flow.

An aircraft experiences a technical issue mid-flight. Critical thinking skills are

employed by the flight crew to diagnose the problem, consider available solutions,

and implement the appropriate corrective actions to maintain the safety of the

flight.

A pilot is planning a flight through mountainous terrain. Critical thinking involves

evaluating the potential risks associated with the route, considering factors like

weather, altitude, and terrain clearance, and implementing strategies to mitigate

those risks.

Effective communication is vital in aviation. Critical thinking is necessary for pilots

and air traffic controllers to understand and convey information accurately. For

instance, a pilot reporting a fuel emergency needs to communicate the severity of

the situation clearly.Aviation professionals encounter new technologies, procedures, and regulations.

Critical thinking is required to adapt to changes, learn from experiences, and apply

knowledge to evolving situations, contributing to ongoing safety improvements.

Critical thinking in aviation involves the ability to analyze, synthesize, and evaluate

information to make well-informed decisions. It is a cornerstone of aviation safety,

helping professionals navigate complex and high-stakes situations to ensure the

well-being of passengers and the overall safety of air travel.

When SMS enterprises deviate from processes, special cause variations could be

classified as common cause variations and assessed as a critical part of the process

for the process to function. Drift is the root cause of accepting special cause

variations into a process, with several sub-classification layers of. Just as the Swiss

cheese model to some extent controls the locations of and size of the holes in the

Swiss cheese, an SMS enterprise, both airport operators and airlines control their

acceptable drift. 

That drift goes untouchable may not have any impact on

operations or the outcome. Unintended, and unnoticeable drift does not equal a

hazardous condition, but the issue is when SMS operators conducts analyses of

their systems and processed, they are based on incorrect data leading operators

down an unknown path. Special cause variations, such as accepting ice on the

runway as common cause variation, or special cause variation, such as accepting

dry snow accumulation on the wings as common cause variation, may in the

future, and have in the past caused major airports and airlines occurrences.

OffRoadPilots