If you had $200,000 in the bank and a $200,000 mortgage, your net debt is zero. You could take the money out of the bank and pay off your mortgage and your net worth would not have changed. You could then take another mortgage on your house and get $200,000 cash and your net worth still hasn't changed.

Delta needs to have cash on hand to deal with day to day operations and they also have reserve cash to deal with unforeseen events. They also have cash on hand to be able to take advantage of any investment opportunities that are available or will be available.

Right now they have about $3.3 billion in real cash and another $1.8 in a revolver (like a revolving home equity loan, except a lot bigger) that they can draw on whenever they like. In order to report net debt, they subtract the $3.3 billion from their real debt number to deal with the fact that, theoretically, they could take all that cash and use it to reduce debt.

That is why "cash on hand" is often reported, but it is a next to useless statistic most of the time. In a case like American, sitting on the doorstep of the bankruptcy court, the cash can make all the difference in the world. Delta right now is producing a lot of free cash flow and they look to continue to produce that cash flow well into the future, so their cash on hand is lower, percentage-wise, than many other carriers. Delta could borrow more money and increase their cash on hand but that wouldn't affect their financial condition one iota other than to increase interest payments. Delta's focus on reducing debt is reducing their monthly interest payments which increases profits. That is smart in my opinion.