What factors caused catastrophic crash between William Byron and Ty Dillon?

Byron's race came to a sudden end after 236 of 267 laps at Las Vegas Motor Speedway

William Byron had a chance to win Sunday's NASCAR Cup race at Las Vegas Motor Speedway, but lost the lead after nearly losing control in Turns 1 and 2. As he refocused and set his sights on taking the lead back, Byron's race ended abruptly in a violent and unnecessary wreck.

Byron's No. 24 Hendrick Motorsports Chevrolet slammed into the back of the slowing No. 10 Kaulig Racing Chevrolet of Ty Dillon, who was off the lead lap and attempting to pit. What exactly happened to cause the bizarre pit entry smash-up?

After reviewing radio chatter and post-incident interviews, there appears to have been a few critical factors leading up to it.

UPDATE: Dillon's spotter has been fired following the incident

Dillon's role in the collision

First is the fact that Dillon was fairly off-sequence from the primary pit cycle, as the rest of the field had made their final stops about 10-20 laps before him.

Additionally, Dillon never put a hand out the window or signaled to Byron in any way. He also slipped up the track and off the white line just before slowing to pit, which likely indicated to Byron that he was planning to move out of the way.

This was surely reinforced by Byron's own spotter, who told him moments prior: "That 10 [Dillon] should go lane two, lane three."

Now, why would he say that? Perhaps it was because that's what Dillon did for the race leader in the corner prior, or it could have been part of the miscommunication between the two spotters as they attempted to signal to Byron's eye in the sky that Dillon was moments away from pitting.

Communication breakdown

At no point did the No. 24 Hendrick Motorsports spotter say Dillon was planning to pit. While it's still unclear what happened on the spotter's stand, there was obviously a communication breakdown at some point between the two Chevy teams.

On the same lap of the race-ending crash, Dillon's spotter was giving him updates on where race leader Kyle Larson was, who he let pass on the inside of Turns 1 and 2 without issue. He was then told Larson has "got a gap behind him," and that was the last thing he was told about the cars around him before the crash.

"The f*** happened there?" asked Dillon after the impact. The team replied, and while the radio isn't clear, they seem to tell him that Byron never got the information that the No. 10 was pitting.

"Whatever," continued Dillon. "Just put us out of f****** misery anyway. Apologize to everybody. That was terrible."

Over at the No. 24 team, the last information Byron received before the crash was that Dillon would be moving up the track and out of the way.

After the crash, they immediately tried to piece together what happened.

"I didn’t know he was pitting," exclaimed Byron.

"I didn't either," replied the No. 24 spotter.

The No. 24 team continued to discuss the incident as the destroyed car was hooked up to a tow truck. Byron asked his spotter if he was "talking to that dumb motherf*****?"

The spotter replied, and while choppy, here's what we can make out: "I am ... I just told him, you know, hey, you're gonna enter the corner on the bottom, you have hands, you can wave as far as the driver, and then you end up in lane two and you just f****** pit. So, I don't know."

Message left undelivered

Ty Dillon and William Byron crash

Photo by: Getty Images

Dillon later claimed in an infield care center interview: "My spotter told me that he let the 24 spotter know we were coming to pit road."

Byron said otherwise in his own interview, noting: "Nobody said anything to my spotter from what I know. I had zero idea."

At the moment of impact, live-data showed Byron going about 50mph faster than Dillon. He started to spin sideways as he tried desperately to cut under Dillon and avoid hitting him, but there was essentially nothing he could do at that point.

A combination of the information never making it to Byron, the No. 10 being off-sequence, but also Dillon failing to signal while drifting up the track at the last second created the perfect storm for this unusual crash to take place.

It could end up being a wreck that ends Byron's 2025 title hopes. Because of Sunday's DNF, Byron leaves Las Vegas 15 points below the playoff cutline.