ATLANTA (AP) - Delta Air Lines Inc. wants to give itself some more breathing room to deal with $904 million in debt that would come due after it receives a single operating certificate to fully integrate Northwest Airlines into its fold.

Delta said in a Securities and Exchange Commission filing that it will essentially be taking on new debt with a later maturity date to pay current debt that would be owed by Northwest once the FAA certificate is achieved. Delta, which acquired Northwest in October 2008, has said it expects to receive the single operating certificate by the end of this year.

Delta plans a private offering of $500 million in senior secured notes due 2014. It said it would use the proceeds from that offering, along with initial borrowings under new senior secured credit facilities, to repay Northwest borrowings. Aything left would be used for general corporate purposes, Delta said.

The world's biggest airline operator has significant debt obligations and has suffered massive losses amid the drop-off in revenue due to the global economic downturn.

But Delta is generally considered to be in stronger financial shape than some other large carriers thanks to a war chest of $5.4 billion in unrestricted liquidity it had as of June 30. That figure is expected to fall to $4.6 billion by Dec. 31.

Standard & Poor's credit ratings for Delta and Continental Airlines are not as weak as its ratings for American Airlines, United Airlines and US Airways.