Originally Posted by
nologic
How can I identify in advance of booking if there is 15K award upgrade space on Alaska BOS-SFO-BOS?
Also, can I upgrade a discounted companion ticket from my Alaska Air credit card?
Use the "upgrade fare type" buttons to the left on the flight results page. You'll use the "mileage" button. If there is a solid blue box with a white F in it next to your flight, there is upgrade space available. You'll need to be booked into Y S M B or H fare class to use this type of upgrade. If using a companion fare, you should still be able to upgrade so long as the "blue F" (aka U fare space) is available for 2, and your fare class is one of the ones above. You'd need 30K miles to upgrade both passengers. Just a note, YSMBH fare classes are some of the most expensive on the flight. Depending on how full your flight is and how far from departure you are, you may find them more expensive than just purchasing a first class seat.
More info on mileage upgrades here:
https://www.alaskaair.com/content/mi...class-upgrades