Spirit Airlines' latest expansion shows it has no concern over potential ultra low-cost encroachment

Spirit Airlines is turning its attention to Minneapolis in late 2013 with a seasonal push to four new destinations to complement its existing service to some of the largest markets from Delta's fortress where the legacy carrier offers 456 daily departures.

The new links Spirit plans to introduce from Minneapolis in Nov-2013 reflects its stated goal for 2013 of connecting the dots in its network after making a huge domestic push beginning in 2010 into a number of major US metropolitan areas including Chicago, Dallas, Denver, Houston and Minneapolis, a market Spirit entered in Jun-2012. Just prior to that push the carrier plans to transition its Phoenix operations from Mesa Gateway to larger Sky Harbor, joining Frontier Airlines in jumping from Mesa to the larger and more well-known airport.

Spirit is forging ahead with its business model against the backdrop of the recent resignation of board chair William Franke and the sale of Spirit stock owned by his investment firm Indigo. The moves have fuelled speculation that Mr Franke is pursuing Frontier in order to fully transition that airline into a true ultra low-cost carrier.