Surging jet fuel prices, up roughly 80% since late February 2026 amid Middle East geopolitical tensions, represent the dominant near-term pressure on airline balance sheets and have accelerated liquidity strains for leveraged carriers. Spirit Airlines ceased operations in early May after its second Chapter 11 filing in under a year, illustrating how unhedged exposure and prior losses can turn incremental costs into existential threats. JetBlue, carrying about $9 billion in debt and posting six consecutive years of losses, faces the highest reported analyst-assessed default risk through 2027, while Frontier and Allegiant show elevated but lower probabilities; American Airlines contends with negative equity and execution challenges despite larger scale. Major network carriers such as Delta and United have posted stronger cash flows, but industry-wide margin compression from fuel and labor costs continues to shape trader focus on which names may file by year-end.