It isn’t only that, it is that in addition to the cost of servicing that debt, some of that debt will be due in the next couple of years.
There are, IIRC, two tranches maturing, one for a half billion and another for three quarters of a billion. Both of these were sold back when things were good and the company is currently only paying 3 and a half to 4 percent on this money. They are going to need to sell new bonds to pay off the old bonds and that causes a couple of problems.

For one, many of the resources used to collateralize the initial bonds have lost value. Airplanes are parked, many airlines around the world have failed, and there is a glut of used planes driving down the prices. Similarly, with nearly everyone downsizing, gates and slots aren’t the value they once were. So the same assets that collateralized the original bonds may not be enough to collateralize their replacements.

Another issue is that the replacement bonds are unlikely to sell at the same coupon rate as those original bonds. The last bonds that the company sold this summer - $2.5 billion worth - they sold at an effective rate of 12%. So let’s say the 1.25 billion in bonds gets refinanced at 10% rather than 4%, that will cause an increase in the annual debt service of $75 million. The company already pays about a billion dollar in debt service annually, and unless the bond buyers can be calmed down by better earnings and brighter prospects that can only go up.

So I wouldn’t recommend judging what is going on simply by burn rate versus liquidity, you have to judge it by what the market thinks of the company bonds. Because if they can’t bring the cost of borrowing down as that older debt comes due, the increased debt service costs will put the company in a death spiral. However it got there, it’s not going to be able to withstand servicing $40 billion in debt at 12% interest, it just can’t.