In order to book an upgradable fare on United you have to buy a ticket in fare class W or higher. Here are the fare classes above W.
V
Q
H
U
E
M
B
Y
Only airlines could convolute something so simple as the ordering of the alphabet.
Related
Tonight I was a guest on Sirius NASCAR Radio ch.128/XM
Here’s my annual tech rendition of ‘Twas the Night Before