Frontier Airlines is preparing to take delivery of its first aircraft formerly operated by Spirit Airlines, with Airbus A321neo N731NK set to become N814FR. The 2024-built A321neo was withdrawn after Spirit ceased operations in May and was ferried from Marana to Tucson on September 28 for its next chapter.

However, N731NK is only the beginning. It is one of ten former Spirit A321neos that Frontier is leasing from AerCap, with deliveries expected between the fourth quarter of 2026 and first quarter of 2027. The transfer marks another twist in the history of two competitive Ultra-Low-Cost Carriers (ULCCs) carriers that once planned to merge.

N731NK Will Get A Second Life With Frontier Airlines

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N731NK, manufacturer serial number 11937, is barely more than two years old. The Pratt & Whitney-powered A321-271NX was delivered to Spirit in July 2024, and entered service later that month, configured with eight Big Front Seats and 227 standard seats. Its remarkably short first career reflects just how young parts of Spirit’s fleet were: at the time of its demise, the carrier’s entire Airbus fleet averaged only 8.2 years old, with dozens more A320neos and A321neos still on order.

After Spirit shut down, N731NK was stored at Pinal Airport (MZJ) before being repositioned to Tucson International Airport (TUS) on September 28. Flight-tracking records show the short ferry as Nomadic Aviation flight OMD323, while fleet records identify its planned Frontier registration as N814FR. It will be an unusually young secondhand addition to an airline that has itself spent years building around Airbus’s A320neo family.

From a fleet commonality perspective, the aircraft is an obvious fit. Frontier already uses Pratt & Whitney GTF engines across its A320neo-family fleet and selected the same powerplant for another 91 A321neos in 2025, taking its total GTF commitment to 235 aircraft. Frontier currently configures its A321neos with 240 seats, so the current work at Tucson is not only about repainting the aircraft, but also adjusting the interior from N731NK’s 235-seat Spirit layout.

Frontier Is Taking Ten Ex-Spirit A321neos From AerCap

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Frontier’s agreement with AerCap, signed on August 29, covers ten A321neos that are all former Spirit aircraft. The group consists of jets delivered to Spirit during 2024, giving Frontier access to nearly-new aircraft without waiting for fresh Airbus production slots. It is an intriguing outcome for two airlines that were pursuing a $2.4 billion combination only four years ago.

According to publicly reported information, N731NK is set to become N814FR, and is set to be the first of the ten aircraft to enter the Frontier fleet after work is completed in Tucson. However, N724NK and N725NK have also been ferried to Tucson and already have Frontier registrations assigned to them, so they will likely be following in short order.

The deal also forms part of a broader reshaping of Frontier’s fleet. Days before signing with AerCap, Frontier agreed to return 13 Airbus A320neos early; it said that transaction combined with the new A321neo leases would maintain similar capacity with fewer aircraft and lower costs, highlighting the larger jet’s productivity. Frontier currently has 68 186-seat A320neos and 69 240-seat A321neos in operation, along with 27 A320ceo-family aircraft, for a total fleet of 164 aircraft.

Spirit Aircraft Are Finding New Homes Around The World

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Frontier is far from the only beneficiary of Spirit’s fleet becoming available. Former Spirit Airbuses have already resurfaced with carriers across Europe, Asia, and Australia. Most notably, Uzbekistan’s FLYONE Asia has placed two ex-Spirit A321neos into service, while Vietravel Airlines has taken three former Spirit A320ceo-family aircraft, and Germany’s Condor is adding former Spirit A320neos.

FLYONE Asia provides the closest comparison with Frontier because its two aircraft are also A321neos. Former N739NK was delivered new to Spirit only in late 2024, while N742NK followed in early 2025; both have already begun new lives in Uzbekistan. Vietravel’s latest acquisition is the former N676NK, which crossed the Pacific in September before becoming VN-A292 and entering service on October 1. Meanwhile, Condor is picking up four A320neos to add to the seven that it already operates.

Others have followed different paths. Qantas subsidiary Network Aviation built a nine-aircraft A319 fleet from former Spirit jets, while GlobalX has agreed to acquire three ex-Spirit A320 airframes to add capacity while lowering its fleet age and maintenance. Ryan Goepel, GlobalX CFO, described it as “a highly attractive opportunity” that it couldn’t refuse:

“We would be almost negligent if we didn’t pursue those aircraft today because that sets us up not just for quarters, but for years.”

At the opposite extreme, some remarkably young Spirit A320neo-family aircraft have already been dismantled for engines and parts, illustrating how valuable individual GTF-powered components can be. Fortunately, N731NK has been spared that fate, and is about to embark on its second life with Frontier as N814FR, becoming the first of ten former Spirit A321neos set to join its onetime rival.