Decision Making and Error in Aviation

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Ref No: 3365

Executive Summary.

The article focuses on some of the most common accidents that were caused by the year 2001 to 2011, to turboprop and aircraft which were being used to carry cargo, passengers and ferry trip.

While constructing the content of the paper, the content and style were kept similar to the previous review of the Global Fatal Accidents. The major findings of the research conducted are listed below:

• A number of Fatal Accident Globally:

A total of 7,148 deaths including the passengers on the aircraft along with the crew members, were reported in the total of 250 fatal aircraft accident between the years 2001 to 2011. The percentage of occupants that were killed during these accidents accounted for 70% of the total number of passengers on board.  However, the study revealed that the with the increase in the time frame, the total number of fatalities were decreasing whereas, it was found out that the number of deaths per year had fluctuation.

• Factors & Consequences

• An airline related primary causal factor was the cause of almost half of the fatal accidents.
• The factor that found out to be most common and occurred most frequently included the “Flight Crew Skills/ Flight Crew Flight Handling”. It accounted for 14% of the total number of fatal accidents. This factor also accounted for the most common joint factor and related to events in which the aircraft was controllable. This includes failure of both aircraft, single and double engine.
• Along with the factor of Flight handling, another most common factor involving one of the airlines most common casual factor include, “Omission of action or inappropriate action”.
• The term “Omission of action or inappropriate action” refers to a situation where the crew members of the flight are unable to control the descent of the aircraft lower than the decided height, also known as the minimum height for decent or the safe height. It also refers to being unable to fly when there is a missed approach or not being able to rectify the configuration of the aircraft during take-off.
• Another common factor observed with at least a single airworthiness was the “Engine failure/malfunction or loss of thrust”.
• One of the most common factors with regards to circumstantial factor was found out to be “Poor visibility or lack of external visual reference”. The term general weather is used to describe accident which is caused due to heavy rain or snow, including icing and winds of very high speed.
• The research revealed that the most common and frequently occurring accident type was due to Loss of control. This accounted for fatal accidents to the aircraft. This loss of control events is further classified into 4 different categories. These categories include:
  1. Accident due to technical failure.
  2. Accidents as a result of non technical failures.
  3. Accidents due to icing.
  4. Accidents resulting due to unknown reasons.

Among these four, non-technical failures occurred more frequently.

• More than third of the fatal accidents were caused due to aircraft catching fire after the crash. However, these accidents did not occur on their own, rather they were a result of some other consequences. These fire in aircraft accounted for only 5% of the total number of fatal accidents.
• Three out of the 250 fatal accidents were accounted for Mid-air collisions (1%).

 

Question # 2

Reason’s Swiss Cheese Model

In the year 1990, James Reason anticipated an approach to the find out the reason which initiated the error during flights due to aircraft crew. This model is commonly known as the “Swiss Cheese” model of human error.

An illustration of this model is presented in figure 1, which shows four level of interdependent reasons for the occurrence of human error during flights. The first level of unsafe acts which caused the human error is associated to the error caused by the pilot. Most of the factors are uncovered at this level and that is why the major focus of accident investigation team lies on this factor.

The Swiss cheese model has been of great help for the investigation team looking into the causes of the fatal accidents occurred to the aircraft as this model deals with hidden failures that might have occurred during the event. These events are particularly those which in other cases would have been left undiscovered for years and months.

Other three levels of human error that can possibly be the cause of the accident are described by the Swiss cheese model which may have been left undiscovered in other cases. This includes the flight crew’s condition that might have affected the overall performance of the flight.

These are defined as the preconditions responsible for the unsafe act. These conditions may include the lack of effective communication, poor coordination and mental fatigue. This is commonly referred as Crew Resource Management (CRM). In these circumstances, due to mantel fatigue, the pilot becomes unable to effectively communicate with the other crew members, as a result, wrong decisions are taken which often becomes the cause of the accident.

However, failure caused by the system (holes) need to be identifying during the period of investigating the accident or detecting them and rectifying them before the occurrence of such accidents is even better.

Following are the functions that are observed in all the defenses.

• Contain and eliminate the hazards should they escape this barrier
• In the case of failure of the hazard containment, they should be able to give the resource to escape and to rescue.
• Introduce barriers for safety linking the hazards and losses.
• Whenever there is kind of danger, they must have warnings and alarms.
• Bring back the aircraft system to the state where its safe.
• Being able to create the understanding and awareness of local hazards

Unfortunately, there are “holes” in those defenses. The “holes” have been observed to change with respect to the changes in the conditions of working and procedures.

The two common types of human error responsible for “holes” are the active failures and the latent failures.

Active Failure – (operator actions) These failures include the errors that affect the aircraft immediately.

Latent Failure – these failures include the actions which have an effect that is delayed. The reason of delayed effect may include tools that are inadequate, designs that are poor, lack of proper training and inability to supervise properly.

There are always chances of defenses to have “holes” and also on the part of humans to make errors. Therefore, it is utmost important to look for these holes and rectify them before they result in the events responsible for the accidents.

(Figure 1)

Analysis of the Human Factor and Unsafe Acts

Two categories can be made one the unsafe acts of pilots: violations and errors (Reason, 1990). The term violations are used to define the ignorance of rules and regulations willfully.

These rules and regulations are for the safety concerns of the flight. Whereas, the term errors is used on the other for the mental and physical state and the activities of the crew member that could be the cause of failure to achieve the desired outcomes….

(Figure: 2)

Table # 1 Examples Selected for the Pilot’s Unsafe Acts

Error: Errors due to lack of Skill Involuntary use of flight controls There are missing steps in the complete procedure Unable to control the aircraft Omitted checklist item Failed to prioritize attention Poor technique Breakdown in visual scan   Decision Errors Exceeded ability Inappropriate maneuver Poor decision Misdiagnosed emergency Improper procedure Unable to respond to any emergency effectively.   Perceptual Error caused because of False impression Disorientation of Space Unable to judge the altitude, distance or air speed