Abstract
In this study subjects kept diaries about unintentional acts during driving. They were asked to record errors at skill-based level: slips and lapses. They also recorded the circumstances preceding there errors and the consequences for road safety. It is argued that in conditions controlled by latent failures cognitive processes procedure not only skill-based errors but also rule- and knowledge-based errors. It is claimed that strategies to increase safey should be directed at these latent failures, rather than at the errors that follow from them.