An analysis of accident reports from the air-traffic control, aviation, highways, and maritime sectors suggests areas where introduction of autonomous functionality could have materially affected the outcome. The effect of replacing or augmenting the human operator in the causal chain of the accident is considered and changes to the outcome are suggested. The functionality and assurance of the autonomous functions are considered as are the interactions with operators. Common themes are extracted from the accident studies and are used to draw conclusions about the potential benefits from introduction of autonomous functionality.