American Express is providing a $100 million loan and prepaying $500 million for Skymiles.

The loan is presumably part of Delta’s process lining up debtor-in-possession financing for a bankruptcy filing. Today’s 8-K filing details the transaction in substantial detail.

American Express, of course, issues the co-branded Delta Amex cards, Delta is a key partner in the Membership Rewards program, and Delta benefits are key to the Platinum and Centurion products.

In other words, Delta needs to keep flying for American Express’ profitability.

When United filed for Chapter 11, BankOne which issues the United Visa, provided $600 million in debtor-in-possession financing. Frequent flyer miles are truly big business. We’ve reached a situation where airlines need to exist for banks’ profitability if for no other reason.