In response to a "60 Minutes" investigation into the Federal Aviation Administration's (FAA) oversight of Allegiant Air, Sen. Bill Nelson, D-Florida, penned a letter to Department of Transportation (DOT) Inspector General Calvin Scovel calling for an investigation into the FAA's enforcement actions and its correspondence with the budget airlines company.

"The traveling public deserves to know whether the FAA is conducting thorough safety oversight of Allegiant. Anything less could lead to disastrous consequences," Nelson wrote in the letter addressed to Scovel.

In the seven-month-long investigation, "60 Minutes" correspondent Steve Kroft found Allegiant Air had more than 100 serious mechanical incidents between January 1, 2016, and the end of October 2017. These issues include mid-air engine failures, aborted takeoffs, rapid descents and flight control malfunctions.

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Through the Freedom of Information Act, "60 Minutes" requested more than a year's worth of reports from the FAA regarding Allegiant and seven other airlines. They received the corresponding documents from each of the airlines except Allegiant, which objected. The FAA later overruled Allegiant's objections and produced the documents.

They showed, on average, the airline was nearly three and a half times more likely to have mid-air breakdowns than American, United, Delta, JetBlue and Spirit.

In his letter, Nelson specifically calls on the DOT to conduct a full audit review of the agency's policies and communications with Allegiant.

"Given the critical implications your findings may have with regard to aviation safety, I urge you to expedite this review. I appreciate your prompt attention to this request," the senator wrote.

The FAA provided the following statement to CBS News in response: