Leverage itself is not a problem in an healthy business. Actually, if the business works it is often a good idea in order to amplify the profits.
The problem here, disregarding for a second the debt situation, is that the company is not making money in its core activity, which is flying passengers from A to B. In this context leverage is only going to make the situation worse.
Of course the passengers love the product, they are flying under cost price. I would love it too. Until it lasts.