Dalta and Northwest Airlines.

Delta Air Lines and Northwest Airlines on Monday night announced plans to merge their vast domestic and international networks, creating the world's largest airline.

The proposed merger would be the largest U.S. airline deal ever, creating a global giant with more than 800 jets, 6,400 daily flights and nearly $32 billion in annual revenue. The carriers estimate the value of the new company at $17.7 billion dollars, far above their current market value.