Circumstances where "looked-but-failed-to-see" accidents arise are a particular subject of study. In order to better understand why normal drivers could miss a relevant event signaling danger, more than 500 accidents were analyzed in-depth with regard to driver-environment-goal interactions. Results show four typical situations that imply two distinct mechanisms. When a failure arose at the perceptual stage, drivers actually never saw the danger while they were going straight at a junction or turning left to park their car. When failure arose at the processing stage, there was evidence that drivers saw the danger even when their recall of it was lacking. In fact, drivers saw the danger too late to avoid collision when they were overtaking another road user or trying to find his/her way. These are called "looked-but-failed-to-see-accidents". Accident patterns are discussed according to driver's goal involvement and local setting to suggest directions for further investigation with a special emphasis on change blindness.