A HOTWIRE clearance fare can be any major airline that participates (United, American, Northwest, Continental, US Airways, America West, Delta Air Lines, Hawaiian, Aloha or Midwest Airlines) and could have no more than one connection. If you need to fly on NW, using an opaque provider (PL or HOTWIRE) isn't your best bet. Keep in mind that HOTWIRE and Priceline purchases might not book into an upgradable or mileage earning fare class.