How come not all segments are upgraded in my Mileage Upgrade flight search?
If upgrades are not available, nwa.com Reservations will return non-upgraded fares. It is possible, if upgrades are not available for your whole itinerary, only a portion of the itinerary will be upgraded. You will be charged mileage for each leg of your journey that contains an upgraded segment. Please check the cabin class carefully before proceeding with your purchase.