INDIANAPOLIS — They call the Indianapolis 500 “The Greatest Spectacle in Racing” for its high speeds, rich history, enormous crowd and the take-your-breath-away competition.

This year, IndyCar is hoping the 99th running of the event won’t be a spectacle because of a serious on-track incident.

Concern hangs over Indianapolis Motor Speedway after the cars of Helio Castroneves, Josef Newgarden and Ed Carpenter all went airborne during practice sessions in the 10 days leading up to Sunday’s race.

All three drivers walked away unscathed, but IndyCar officials scrambled on qualifying day for a solution.

All three drivers were driving Chevrolets, and the manufacturer worked with the series on adjustments to the bodywork of the cars, plus a reduction in horsepower before qualifying.

One day later, James Hinchcliffe suffered a life-threatening injury when he slammed into the turn three wall at more than 220 mph and a broken piece of his suspension pierced his left thigh. Hinchcliffe’s accident was unrelated to the three cars that had gone airborne, but one of IndyCar’s most popular drivers was rushed into surgery in critical condition and will miss Sunday’s race.

The four wrecks have many wondering if Sunday will see a safe race.

“This will never be a safe race — it’s an open wheel car going 230 mph over three and a half hours trying to win,” said Rahal Lanigan Letterman Racing driver Oriol Servia. “Safe is not really what defines it. It will never be. But I think it could be safer than what we’ll do Sunday.”

IndyCar officials aren’t certain what caused the three cars to lift off the track following mild crashes. Although some wanted to point to the new body kits Chevy and Honda are allowed to use this season, most drivers doubted the manufacturers were to blame.