Budget carrier Spirit Airlines announced it filed for Chapter 11 bankruptcy on Monday in the face of mounting losses, increased labor costs and a highly competitive air travel market. The airline has failed to return to profitability following the downturn in air travel caused by coronavirus pandemic lockdowns.

The disparity in size between the low-priced airlines and the top firms underscores a fissure in the industry separating budget carriers in select markets from the major airlines that dominate flight offerings nationwide, Mike Boyd, president of aviation consulting firm Boyd Group International, told ABC News.