Be aware that you may not get NW miles when you book your flight on Delta and Delta puts you on a Song flight operated by Delta.

This just happened to me. I booked my flight on Delta web site on 12/16 to fly from JFK to MCO on 12/25 (DL 2569)and return on 12/26 (DL 2570). When I booked the flight, I called Delta and asked the agent to enter my NW WP#. The agent did and my WP# showed up on my boarding passes. My flights had "DL" flight #s and the agent did not say anything to me about not getting NW miles or that I was actually going to fly on Song, operated by Delta. When I got the email for my itinerary, it came from Song but I did not think much about it since I booked on Delta. When my miles did not show up on my NW account, I called Delta and was told that I would not get NW miles because the agreement between DL/CO/NW excluded miles being awarded from Song flights. I asked how I could have known/avoided this since I booked my flight on Delta and Delta put me on Song flight. Also the agent I spoke to while booking the flight did not tell me this when he entered my NW WP #. I told the agent that I wanted my NW WP# entered because I wanted my miles credited to my NW account. The agent apologized and transfered me to a supervisor so that I could voice my complaint. The supervisor apologized for any inconvenience they had caused me. She said that the agents were not quite familiar with the terms of the agreement. She also said she would credit the miles to my Skymiles account and put a note in my profile so that the agents would inform me on any future flights that would not receive NW miles.

So, if you are flying "Delta" and want the miles in your NW account, double check to make sure that you are not put on Song flight operated by Delta. This is regardless of what fare you paid. I paid Y fare for the above flight.