Dan Wheldon was killed when his head hit a post in the fencing at Las Vegas Motor Speedway, contact that created a "non-survivable injury" to the two-time Indianapolis 500 winner.
IndyCar officials released their findings Thursday of the Oct. 16 accident in the season finale. Wheldon was killed in an early 15-car accident when his car launched into the catchfence.
The reports finds several factors contributed to what became a "perfect storm," and no one reason could be singled out as the sole cause of the accident.
IndyCar found it is "impossible to determine with certainty that the result would have been any different if one or more of the factors did not exist."
The race had a season-high 34 cars and was held on a high-banked oval, and IndyCar CEO Randy Bernard says the size of the field and the banking itself were not solely responsible for the accident.