The South Florida-based low-cost airline and Airbus announced Thursday that they have entered into an agreement for the firm order of 20 Airbus A321 aircraft.

The companies said the aircraft are in addition to the 96 aircraft not yet delivered under Spirit's existing order.

The new planes will be scheduled for delivery between 2015 and 2017.

"We are pleased to expand our partnership with Airbus and excited about the growth opportunities and additional cities we will be able to liberate from high fares with the addition of these aircraft," said Ben Baldanza, Chief Executive Officer of Spirit Airlines.Spirit Airlines makes massive plane purchase.