Spirit Airlines aims to decide on its next aircraft order in about six months, with the ultra low-cost carrier emphasising that it is not tied to the Airbus A320 family.

"It's generally true, [that] if you stick with one type there are efficiencies, and generally there are, but there may be an opportunity for a second fleet type if we get the right economics," Spirit chief executive Bob Fornaro tells reporters at the Boyd Group International Aviation Forecast Summit in Denver.

The airline's current aircraft deliveries will finish in 2021, putting pressure on Spirit to make a decision within the next six months to secure aircraft delivery positions and continue expanding. The carrier had previously indicated it could need up to 125 additional aircraft beyond 2021.

Fornaro says the carrier is engaged in talks with Airbus, Boeing and Embraer in order to know their aircraft better, ahead of launching a formal request for proposals.

Spirit had previously expressed interest in the Bombardier CSeries - now the Airbus A220 - and Fornaro says Airbus' takeover of the programme is viewed favourably by Spirit.

"Having the relationship with Airbus is a positive," he says.

Fornaro previously called the CSeries "a very good airplane", telling FlightGlobal in an interview in 2017 that he believes it would be ideal for small and mid-sized markets.

While the airline had been mulling its next aircraft order for a while, it recently stepped up the process after ratifying a contract with its pilots in February.

Spirit has indicated it expects to grow capacity about 14% in 2019.

Source: Cirium Dashboard