A couple of factors contributed to this fatality. Notice how close the tree is reducing the runoff area in the initial incident. If this tree was removed the wheel most likely wouldn't have bounced back on to the racing surface. Secondly, the current F2 is a brand new series, only the 4th race for this chassis. There are tethers that are designed to prevent wheels from flying off. Still, wheels flew off of both cars in relatively low speed shunts. Williams F1 designed this chassis. ...
Dang, I forgot to add that Brands has been trying to improve the safety of the circuit, but tree huggers have protested the removal of trees, [therefore] Brands has been bogged down trying to make improvements. Hey, at least that tree is safe.