Broken seat belt only partly to blame

The six-month investigation, revealed to the public today (Tuesday) in Atlanta, reported that the broken seat belt, coupled with the collision with Ken Schrader's car and the angle of impact which Earnhardt hit the wall, all played a role in his fatal injuries.

"We conclude that there were a number of factors in which the timing came together to produce this result," said Dr James Raddin, a director with San Antonio-based Biodynamic Research.

He said that Earnhardt's head was forced to turn to the right after his car was struck side-on by Schrader's machine which caused his helmet to slide forward, exposing the back of his skull.

Because of the angle of his head, coupled with the snapped seat belt, Raddin believes Earnhardt suffered a blow to the back of his skull when his car struck the Turn 4 wall.

The fatal blow was caused by the left side of his head hitting the steering wheel or rebounding and hitting the car's rollbar. It caused a basilar skull fracture that killed him instantly.

"We have concluded a head impact with neck tension likely was the cause of the ring fractures in the skull of Dale Earnhardt," Raddin said. "We base that on the autopsy findings that there was a contusion from blunt force impact based on vehicle dynamics.

"We analyzed the belt separation and how that allows a greater separation, the data with the scientific literature is consistent with impact to produce a ring fracture."

Raddin said alternative theories of head whip, Mandibular impact or a combination of the two, as concluded by Dr. Barry Myers - an independent medical authority who reviewed Earnhardt's autopsy photos on behalf of the Orlando Sentinel - were not the cause of death.

"With neck tension alone, I looked to see if there was something that would tend to give us a conclusion, looked at the kind of torso contact that would produce the violent head whip," Raddin said. "I did not see dramatic injuries to the torso. I looked to see if there was dramatic stretching in the back of the neck in pathology findings and that was not found with damage to the ligaments or the bone. A certain head whip does not show damage to ligaments or to the bone.

"A simple head whip does not explain a death caused by blunt force impact to the head. You can get basilar skull fractures that way, but it's not likely."

Raddin said there was not one reason why Earnhardt was killed, but a variety of factors that happened in the milliseconds that it took during the crash.

"There were multiple events, each of which provided factors which contributed, or potentially contributed, to the injuries," Raddin said. "One was a very severe collision at a critical angle to the wall. We see a significant car-to-car collision that occurred very shortly - twice the duration of an eye-blink that pre-positioned the occupants. That pre-positioning in the impact, and the wall impact and the rebound all provide a basis for the displacement of the helmet.

"The seatbelt separated and it separated under load and it allowed additional forward motion. On the basis of that analysis, I can not give a relative contribution that it was 30 percent this or 40 percent that, but what I cannot say is there was no potential contribution when you have a head impact in a setting with the belt separates and allows further displacement."

Dr Thomas Parsons, the medical examiner in Daytona Beach who conducted the autopsy, said Earnhardt suffered a skull fracture that ran from the front to the back of his head.

NASCAR has pledged to install 'black boxes' from next season to help improve car safety. However, it will not require drivers to wear head and neck restraints, although their use will be encouraged.