Fear of Friday 13th is quite common in the English speaking world but it is actually quite a recent phenomena, only going back to the beginning of the 19th century. Though Friday has often been seen as an inauspicious day in the Christian world - due to the claims that Jesus was crucified on a Friday. The No. 13 has long believed to be unlucky and the supposition is that it is because Judas was the 13th disciple and he betrayed Jesus.
There's no good documentary evidence of people putting Friday and 13th together as being particularly bad until a 1907 popular novel called Friday the 13th by Thomas W. Lawson used the fear of the date as a plot device. This would indicate that it was perhaps understood to be significant at least.
According to some studies, many people in the US especially, change their routines significantly to mitigate any bad luck they think will come their way. A BMJ study in 1993 reported that 'the risk of hospital admission as a result of a transport accident may be increased by as much as 52 percent' on the 13th'. However the authors also pointed out the numbers actually admitted for accidents are too small to really state this with any confidence. The vast majority of people go about their daily business, airlines do not report any noticeable reduction in people taking flights on that day for instance.