Spirit Airlines (NK, Fort Lauderdale International) In a further escalation of animosity between United Airlines (UA, Chicago O'Hare) and Spirit Airlines (NK, Fort Lauderdale International), the chief executive of the former, Scott Kirby, called the low-cost carrier's business “an interesting experiment” which has “failed,” and opined it was unlikely the company would keep flying.

The LCC, currently under Chapter 11 bankruptcy reorganisation, responded to United on social media saying: “Our guests love low fares, especially our new Spirit first and premium economy options. Maybe that’s why United executives can’t stop yapping about us.”

In early September, United Airlines added flights to 15 cities, increasing the capacity to give passengers connectivity if Spirit abruptly collapses. After that announcement, Spirit Airlines noted that certain airline executives were “obsessed” with the carrier but that suggesting it would close was “wishful thinking on the part of a high-cost airline looking to eliminate a low-cost competitor.”

Kirby has long been a vocal critic of the business models of low-cost, no-frills airlines and has repeatedly questioned their viability.

Spirit Airlines filed for bankruptcy protection in late August for the second time in less than a year after its previous reorganisation failed to improve its financial position. The company is now looking to renegotiate lease terms and potentially reduce the size of its current fleet, and has also discontinued service to 11 cities.