MIAMI — David Siegel has resigned as Frontier’s CEO “For personal reasons,” and the carrier’s chairman and president have taken over.

Instead of just replacing him with one person, the airline is creating an Office of the Chief Executive which will be made up of Frontier’s President Barry Biffle and the board chariman Bill Franke. These two will now direct the airline.

The announcement was a surprise to many. Siegel has been at the reigns of Frontier since January 2012, and quite a bit has happened at the company since he started. A little more than a year after Siegel started, Franke’s investment firm, Indigo Partners, purchased Frontier, and the new management started the process in shaping Frontier into a Ultra-Low-Cost-Carrier.

The road in moving Frontier has been difficult to say the least; many loyal Frontier customers in the carrier’s hometown were very unhappy with the changes to Frontier, especially since the airline has been reducing its presence in Denver. Plus earlier this week, the U.S. government came out and said that Frontier had the highest complaint rate and worst on-time performance in March.

Maybe with Biffle and Franke directly overseeing Frontier’s operations day to day will help Frontier’s transformation into a ULCC. Biffle and Franke both have previous experience in running and turning a LCC into a successful ULCC-Spirit.