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
In The Short View in yesterday’s FT James Mackintosh writes
Here’s my crack at estimating the number of screens in
Unless you were somehow seemingly off the grid earlier this