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
The idea that AI simply “assists” or “augments” us is
Apple released their FY 2016 first quarter results today. Here