[marybethtyson]

If I'm already booked with northwest airlines and I want to switch my flight to another time on the same day, why do I have to pay so much money?

This is why I continue to fly southwest!

[PHXFlyer]

From your other post you said they were asking somewhere in the neighborhood of $1700 to make the change. Without details my guess is that you're trying to change the outbound portion of the trip. When this happens it's like starting over from scratch and they re-fare the whole ticket. I'm also guessing that your trip is probably less than a week from now. When you bought the ticket you were able to buy the lower priced advance purchase fares. Now that you are closer to your departure date those fares are no longer available. They are charging you the difference between the advance fare and the alk-up fare. I've got news for you, Southwest does the same exact thing! They just don't tack a change fee on top of it.

If you really need to take the earlier flight Northwest offers FlyNow. For a $50 fee you can be confirmed on the earlier flight, but it has to be no more than three hours earlier than the flight you want the same day that you travel. In your other post you mentioned you wanted to take the 11 AM flight. At 8 AM you can call Northwest or just go to the airport and if there are sufficient seats on the earlier flight they will confirm you for $50. If the flight is full you can still standby and if there's an empty seat when they finish boarding they'll go to the standby list.

Good luck.