CEO departs at Frontier Airlines; president and chairman will manage low-cost carrier

The CEO of Frontier Airlines is resigning immediately, citing personal reasons.

The departure of Dave Siegel comes two days after the government said Frontier had the highest complaint rate and the worst on-time performance among the nation's 14 leading airlines in March.

Frontier, based in Denver, said Wednesday that Chairman Bill Franke will manage strategy and finances and President Barry Biffle will handle daily operations.

Siegel has led Frontier since January 2012. Frontier has been shifting to a so-called ultra-low-cost carrier that offers low base fares but adds fees for many services.