Abstract
Human performances resulted from accident investigation are not always the same as the human performances assumed at the design stage of the machines.
Accident inquiry itself has many difficult points for drawing up the true image of human error, such as the charactor of investigation team, scientific reliability of investigation methods and validity of logic of representation of accident phenomena.
However, from limited experience of aircraft accident inquiry on no gear landing and near miss, many human performances should be considered to have different pattern at the dynamic phase of man-machine system.
