If I want to upgrade from LAX to LHR and return on United do I have to buy the basic economy ticket first and then hope upgrades are available for miles, or can I find this out before I buy the ticket? Never tried to upgrade before, just got tickets with miles.

Your mileage cost and upgrade priority will depend on your fare class and status. More expensive tickets can be upgraded for 15,000 miles each way and cheaper tickets for 30,000. The cheapest tickets are not upgradeable. I'm assuming you don't have status with UA, in which case your place in the upgrade queue will be after status fliers.

In general, you won't get an upgrade confirmed when you buy the ticket.

There are two ways you can find out if upgrade inventory is available. The easiest is to call.

Or, you can check via the website--to do so, you need to make sure that your ual.com profile is set to &quot;expert&quot; availability mode (found under &quot;my travel preferences&quot; in the profile) and that you are logged in. If so, then do a search for a <b>standard</b> business class award. Find the flight you want, mouse over the &quot;flight details&quot; link; there will be a box that appears with lots of letters and numbers; look for &quot;NC&quot; inventory. If you see &quot;NC 0,&quot; no upgrades are available; if you see something like &quot;NC 4,&quot; then that means there are four upgrades available.

If there is availability, upgrades can be confirmed as soon as the reservation is ticketed. If not, you'll be put on a waiting list.

FYI, to upgrade with miles, you need to purchase an eligible fare: H/M (30K miles each way) or Y/B (15k miles each way). These will be more expensive than the lower discounted fares.

To add to the above, finding NC0 means that there any upgrades available now, but they may become available. This is especially true if the flight date is very far away. UA will release seats for upgrades as the flight date approaches, if there are unsold seats.

There IS another way to get your upgrade. Buy the cheapest ticket you can, and then when you check in for your flight, ask &quot;how much&quot; it will cost you to upgrade (one way) on your flight. You will have to pay an amount that I believe (?) is somehow based on the miles you fly on the flight.

As an example, I just paid $599 to fly bus class on UA from ORD to FRA last month. I paid $550 (?) a year ago to fly bus class on UA from ORD to LHR. I flew regular economy class on the return flights, as they were daytime flights and I did not need to be able to stretch out and sleep like I do for the night flights TO Europe. I know, this kind of upgrade costs CASH, not FF miles.

Other than that, yes you can buy a more expensive econ ticket (at least $300+ more than the cheapest ticket in my experience). If seats are available, you will get them at booking, using your FF miles. If not, you can be put on a waitlist. I fly a lot to Europe and Bangkok. Most of the time I've gotten my waitlist upgrades before flying, but not EVERY time, and I'm premier exec with UA. I have flown about 65k miles this year so far. Even that status doesn't guarantee me a bus class seat with miles! Paying at the check-in counter WILL get you a seat, provided bus class isn't already fully booked.

Good luck!