ABSTRACT
The "70% factor" statistic underlies most justifications for the integration of Human Factors knowledge into aviation operations. However, the cause-effect relationship this statistic suggests reflects views on human error prevailing some forty years ago and it ignores a significant body of recent research on the subject. The integration of Human Factors knowledge is essential to aviation not because most safety breakdowns are caused by lapses in human performance, but because error is a normal component of human behaviour. Error is the inevitable downside of human intelligence, it is the price humans pay for being able to "think on our feet". The notion of acceptable errors underpins proactive error management. Operational contexts and, most importantly, systems design, should allow operational personnel second chances to recover the consequences of errors. Historically, accident investigations have backtracked events under scrutiny until they found actions or inactions by people which generated outcomes different to those intended.
