Aviation accident analysis

Aviation accident analysis is performed to determine the cause of errors once an accident has happened. In the modern aviation industry, it is also used to analyze a database of past accidents in order to prevent an accident from happening. Many models have been used not only for the accident investigation but also for educational purpose.
Per the Convention on International Civil Aviation, if an aircraft of a contracting State has an accident or incident in another contracting State, the State where the accident occurs will institute an inquiry. The Convention defines the rights and responsibilities of the states.
ICAO Annex 13—Aircraft Accident and Incident Investigation—defines which States may participate in an investigation, for example: the States of Occurrence, Registry, Operator, Design and Manufacture.
Human factors.
In the aviation industry, human error is the major cause of accidents. About 38% of 329 major airline crashes, 74% of 1627 commuter/air taxi crashes, and 85% of 27935 general aviation crashes were related to pilot error. The Swiss cheese model is an accident causation model which analyzes the accident more from the human factor aspect.
Reason's model.
Reason's model, commonly referred to as the Swiss cheese model, was based on Reason's approach that all organizations should work together to ensure a safe and efficient operation. From the pilot's perspective, in order to maintain a safe flight operation, all human and mechanical elements must co-operate effectively in the system. In Reason's model, the holes represent weakness or failure. These holes will not lead to accident directly, because of the existence of defense layers. However, once all the holes line up, an accident will occur.
There are four layers in this model: organizational influences, unsafe supervision, precondition and unsafe acts.
Investigation using Reason's model.
Based on Reason's model, accident investigators analyze the accident from all four layers to determine the cause of the accident. There are two main types of failure investigators will focus on: active failure and latent failure.
In order to fully understand the cause of the accident all those steps need to be performed. Investigation that is different from the causing of the accident, then it is necessary to investigate from backward of Reason's model.