Originally Posted by
milemonkey
If a UA flight has a four digit numbers but says it is "operated by US Airways" does this just mean it is a US Air flight? Even though it is showing as UA #1234 I will not be able to upgrade or anything, correct?
Correct.
"operated by US Airways" means that it is a US Airways flight. Enjoy.
The following UA flight numbers are operated by US Airways.
UA1700 to UA2829
The following UA flight numbers are operated by US Airways Express.
UA2830 to UA3899
You can always try to go check-in at the United counter at the airport. Sometimes they'll take pity on you and confirm you UA metal. Just act confused tell them your final destination "via United flight 1721."