Why would you want to waste an upgrade on a short flight like LAX
? If you are going to upgrade, at least do it on a flight with a meal (except for Hawaii). The flight time is short and all you get is a bigger seat and free booze. The First Class seats between LAX
are not even as good as Business Class seats on 3-class planes.
That said, the gate control agent can upgrade you, if they have seats available, but they probably will not unless there is a good reason, such as you are a big frequent flyer or a celebrity have been massively inconvenienced by UA
. You should try to fly on one of the 757s as it is almost impossible to upgrade on the 737s or A320s at the gate. The smaller planes usually have their handful of First Class seats taken by Premiere Milage Plus members who upgraded the night before or earlier.