39.13 When the clerk of the course decides it is safe to call in the safety car the message "SAFETY CAR IN THIS LAP" will be sent to all teams via the official messaging system and the car's orange lights will be extinguished. This will be the signal to the teams and drivers that it will be entering the pit lane at the end of that lap.
At this point the first car in line behind the safety car may dictate the pace and, if necessary, fall more than ten car lengths behind it.
In order to avoid the likelihood of accidents before the safety car returns to the pits, from the point at which the lights on the car are turned out drivers must proceed at a pace which involves no erratic acceleration or braking nor any other manoeuvre which is likely to endanger other drivers or impede the restart.