‘Perfect storm’ of factors led to Dan Wheldon’s fatal crash

No one factor caused the 15-car crash that killed IndyCar driver Dan Wheldon at Las Vegas Motor Speedway, but one ingredient was the unusual situation in which drivers had “almost unlimited” freedom to race wherever they liked around the track, the Izod IndyCar Series said Thursday.

Wheldon, 33, suffered fatal head injuries in the pileup on the 11th lap of the 200-lap race, IndyCar’s season finale, on Oct. 16.

“While several factors coincided to produce a ‘perfect storm,’ none of them can be singled out as the sole cause of the accident,” IndyCar concluded in its investigation.

In the tragedy’s aftermath, critics suggested that there were too many cars, 34, racing too close together in a pack and traveling too fast — at 210 mph or more — for a 1.5-mile banked oval such as the one at Las Vegas. A promotion involving Wheldon also was called into question.

Although the British driver was experienced and had won the Indianapolis 500 for the second time this year, he did not have a full-time ride. But he agreed to a challenge in which he would split $5 million with a fan if he won the Las Vegas race after starting last.

Wheldon had climbed from last to 24th when the accident unfolded in front of him, and “no conduct by Dan Wheldon’s driving … was found to have contributed to the cause” of the crash, IndyCar said. “The promotion was not causal to the incident.”

But the series said that although most tracks have one or two grooves on the racing surface that limit how much drivers can maneuver their cars, the Las Vegas track — combined with the design and performance of the IndyCar race cars — gave drivers “almost unlimited movement” leading up to the fatal wreck.

“The combination of the track geometry factors allowed for relative unrestricted movement within the racing pack that had not previously been experienced,” Brian Barnhart, IndyCar’s president of operations, said in a news conference in Indianapolis.

“This movement not only allowed for increased car-to-car contact but made it more difficult for drivers to predict the movement of other drivers around them,” he said. “While the accident could have occurred at any track at any time, the dynamics of the current car and the overall track geometry at the Las Vegas Motor Speedway under race conditions appear to have been causal to this accident.”

Contact between the cars of James Hinchcliffe and Wade Cunningham triggered the chain-reaction crash, which sent four cars airborne, including Wheldon’s.

Wheldon’s car then slammed into a catch-fence pole between the first and second turns that “produced nonsurvivable blunt-force trauma injuries to Dan’s head,” the series said.

IndyCar is rolling out a new race car for 2012 that it expects will be safer, but the series recently said it would not return to Las Vegas next year as planned, citing a need for further testing there with the new car.

james.peltz@latimes.com