A new study found that Frontier Airlines is the most budget-friendly airline for flying out of the Charlotte Douglas International Airport. Using data from the FAA, TripAdvisor, and Air Miles Calculator, researchers at CashNetUSA routed flights from the Charlotte Douglas International Airport to every other major airport in America to find which airlines offer the best prices when traveling from CLT. They found that Frontier Airlines offers the best prices when departing from CLT at just $0.11 per mile. Meanwhile, United Airlines is the most expensive airline flying out of CLT at $0.71 per mile. Charlotte Douglas International Airport Prices: Click here to read the full study from CashNetUSA. ...read more read less