Last weekend, while drivers practiced just hours before the start of qualifying for the Indianapolis 500, a crash occurred that seemed eerily familiar.
Driver Ed Carpenter spun around backwards, heading into the Turn 2 wall. Wind got underneath his car, and flipped it into the air and upside down.
Carpenter walked away unscathed, but watching replays, even the track announcers were puzzled.
The drivers preparing for this weekend's Indy 500 are used to the inevitable crashes at one of the world's top auto races. But usually a car involved in an on-track accident stays on the ground.
The cars seem to go airborne only when they're sliding backwards.
A few days later, Carpenter was driving a passenger car during a promotional event in Detroit. But he says his mind is still on Indy, and the accident that he can't make sense of.
"I feel fine," Carpenter says. "I mean, I was back out in a car five hours later getting ready to qualify for the race. So, there's a lot of issues that they're trying to fully understand and diagnose to come up with a solution."
IndyCar teams spend millions testing cars to understand how they will perform, especially the air foils, which act like upside down airplane wings pushing a car more firmly onto the track.
But this year there's a big change at Indy. Teams are using cars with two different body styles and aerodynamic packages. One is made by Chevrolet, the other by Honda.
Over five days of practice for Indy, three Chevys inexplicably flipped upside down.
And with only days to go before the marquee 500 mile race, Chevrolet Motorsports Vice President Jim Campbell says engineers are poring over computer simulations.
"One of the drivers had a cut tire and lost control after the tire went down," Campbell says. "And the car stayed on the ground the entire time, based on our telemetry data. It was only after he got into the wall when the car got up."
With no clear answer for the flying cars, he says, race organizers have only one other step they can take.
"The qualifying decisions were made to slow 'em down a little bit — gives the drivers a little bit more time to react if the car gets loose," Campbell says.
While that could prevent a spin-out, top Indy drivers fear it may not stop a car from flipping upside down if a wreck does happen.
Will Power is the defending IndyCar series champion. He'll start in second place, leading a field driving at speeds of 230 miles an hour — the take-off speed for some jets.
Yet even in a sport where victory depends on going faster than the competition, Power says slowing cars that may be prone to flip over makes sense.
"I don't think we ever need to race over 230," he says, " 'cause you can't tell the difference standing on the side of the track. Whether a car's doing 240 or 220, looks the same."
Cars typically are tuned to go a bit slower during the race so they can last 500 miles. But Power notes the crashes so far have happened when cars were practicing and qualifying single-file or in small groups.
So, what happens in the thick of the race, when all 33 cars are battling for position?
"It's a tough question," Power says. "Obviously there's a problem there ... For me I just want to stay at the front and stay out of trouble."
But in this Indy 500, the drivers threading their way through the middle or back of the pack must keep an eye on both the competition and whether a crash will suddenly send a flying car hurtling towards them.