It’s a pretty common rule across motorsport that when restarting a race after a safety car period, drivers shouldn’t suddenly speed up and then slow down again. If you’ve ever wondered why not, then this footage from a Formula Vee race at the Barbagallo circuit in Australia should give you a pretty clear answer.

Shot from onboard the car of Kathy Lisson, a concertina effect at a restart bunches all the cars up. Lisson just manages to miss the car ahead but the car behind didn’t have the time to react. They punted Lisson into the car of Stephanie Esterbauer and caused her to barrel roll through the air. Ouch.

Luckily the driver escaped with just a few bruises, though the car is probably going to take a bit of repairing.