Note that NW isn't an option on the web either. Ual.com offers TONS of airlines, both domestic and international, yet no Northwest.

Sometimes I can get NW NON-STOP only flights to appear on UACNXN...But it's a hit or miss. Regardless, they can't be booked...You can select them, they'll give you a fare, but when you go to ticket, it will say for each flight "Seats not available on NW Flight #XXX--Contact issuing airline for more information" Or something like that.

I called UA on it, and they said that NW took away UA's permission to issue tickets.

Quite strange...