https://www.barrons.com/articles/20-...ld-51589298678
Article contains some interesting info on "Credit Default Swaps" which are like insurance for airline bond holders. The more likely the company is to default on their bonds the higher the cost of the CDS. Here's some examples from the article:
Apple: 30 cents per $100 (example for a very strong company)
Southwest: 4.7%. ($4.70 per $100)
Delta: 12%
JetBlue: 1.6%
UAL: 24%
American:
54%
Article also says further Gov intervention with the airlines is an unknown at this time so could change all this.