Head of Safety Franco Uncini explains Hayden crash and the lack of air fences...

The crash involving Nicky Hayden during the GP of Aragon left everyone holding their breath. The American ran off track at turn 16, continuing on through the runoff area and eventually impacting a retaining wall. The Ducati rider was then thrown over the wall, while his bike remained on the other side. The first medical checks confirmed that the American was conscious and had full movement in his limbs. It was also revealed that he suffered no head trauma and did not re-injure his wrist. Nonetheless, he was taken to a local hospital for further checks.
Read more: http://www.gpone.com/index.php/en/201209308381/Uncini-Hayden-made-a-mistake.html#ixzz2837rcSva

(crash video on the link)