Head-On Collisions\n\n One of the most dangerous types of car accidents is a head-on collision. Because these crashes involve the full force of both vehicles colliding head-on, they have the potential to cause significant damage and even death.

a. : to break or go to pieces with or as if with violence and noise. b. : to fall, land, or hit with destructive force. : to decline suddenly and steeply.

The song that Dean is humming to calm himself down on the plane is called "Some Kind of Monster" by Metallica.