[yason]

On the other hand, Spirit as mentioned in the article stopped making profit in 2019. Some years later, chapter 11 filings and then another round.. That's like a 7-year runway (pun intended) to insolvency.

Because fixed costs are what they are, I think, is the reason you can drive the business quite precisely to the brink of inoperation: it could literally come down to pure luck between how full your planes happen to be and how close you are to the next payment of some critical loan whether you can take off into the air for another month or so.