Hi dgzimm and welcome to Flyertalk.


I don't want to make it sound overly complex, but it would matter if the trip you are considering is domestic vs international, and what "instrument" you have to secure the upgrade.

Since you mention United...

If you are an elite member of Mileage Plus, then you will automatically be considered for an upgrade on any domestic United flight (on, I think, pretty much any fare). Priority is based on the level of "elite-ness" in the program, fare paid, and some other stuff. It is kind of automatic.

For international travel, if you have electronic coupons called "Systemwide Upgrades" (normally given to United's most frequent flyers), you can use those to upgrade international flights that are in the middle and upper fare classes (W and higher). In the United forum, you can find information on the fare listings.

As an alternative, anyone can upgrade an international flight by using miles and some co-pay that depends on the fare basis of the ticket. Again, there is more info on the United website.

In your note, it seems that you are talking about upgrading a flight that was originally booked with miles. This is a bit trickier. For domestic flights, I think that some airlines might allow elite flyers to upgrade on award tickets (NW used to). I am not aware of any airline that lets you upgrade an international award ticket that is issued in economy class.

Hope this helps - if you have a specific situation, please let us know and we might be able to give more specific info.