Reader Trey, occasional flyer but frequent upgrader, sings the praises of American Airlines’ upgrades for purchase at check-in and asks:

I travel with relative infrequency, say 3-4 times per year. When I do, I /always/ fly American Airlines because I like their planes, I like their service, and, usually, I like their price. The latest factor keeping my business with them, however, is the availability of $30 500mi upgrades when using Kiosk Check-In. I LOVE it. It’s cheap, fast, and the only way I’ll ever qualify to upgrade from the N or Q class fare I normally book. My question is this: is there any online tool which will let me view historical loads so that I can book flights which normally have room left up front?

The upgrades-for-purchase at check-in can be a decent deal, especially if you’re on a super-cheapo ticket. To maximize your odds of being able to buy one, you want to be on flights with 1) lots of tickets for sale in first class (which is hard to predict, but you can see tickets for sale up until a few hours before the flight) AND 2) with the fewest possible number of top-tier elites on board. These elites might be automatically upgraded by the airline, so they’d jump ahead of you, Trey. But unless you work for the airline, there’s no way to know who’s booked on a flight, though you can expect super-elites to travel to business destinations from main hubs, say, Dallas-New York.

I’m afraid I don’t know of any online service that offers reliable historical information about how many actual seats were available for upgrades into first class. The closest thing out there is UpgradeSuccess.com, which I’ve mentioned here, but the information in their database is pretty thin.

Other sites like ExpertFlyer let you subscribe and see loads for FUTURE flights, but that doesn’t tell you how these flights filled up in the past. FareCast collects this sort of information and gathers it in their database to make predictions about future fares, but again, this isn’t necessarily data that would help you in picking an easily-upgradable flight.

But maybe I’m missing something: Someone out there will surely correct me if I’m wrong. Any ideas?

A deceptively simple question, without a simple answer. For starters, not all upgrades are the same. There are the “unlimited free domestic upgrades” for elites at Continental, but good luck getting them on a popular route, especially if you’re not an ultra top-tier frequent flyer. There are the electronic certificates (e.g., at United Airlines), which improve your chances if you’re a low-rung elite, but you still need to sweat it out, often at the gate. Then there’s the option of using miles. But how successful are travelers at actually GETTING the upgrade?

To really answer the question, we need empirical data, which the airlines are not about to volunteer. A few websites are stepping up to the plate, but they all have a way to go:

UpgradeSuccess.com is building a searchable database of upgrade requests and their successes and failures for the major US airlines. The data are still pretty thin (Northwest has the most data, with just under 1000 flight segments) but the site has an option for sorting the results by elite status. If there were more flights entered into the system, it might be nice to sort by flight route, too.

Looking more globally, WebFlyer maintains an index for both award tickets and upgrades, ranking the airlines in both aggregate and monthly terms. But they don’t tell us how many segments have actually been entered. (n=??) Looking at Webflyer’s May upgrade data, there are only three airlines listed, with Air Canada showing 0% and American showing 100%. I’m pretty sure that Air Canada’s flyers are doing better than that, and American’s are doing worse. The site also collapses domestic and international flights, so you’re comparing domestic U.S. upgrades to first class with, say, trans-Pacific upgrades from coach to business class. (The latter is much more desirable than an upgrade from Chicago to Detroit.)

Both of these sites can only function with your help. So go, enter your segments! Tell them when you tried to upgrade, when you failed, and when you succeeded. Improve the data. It’ll be doing everyone a public service, and maybe in a year or so we can empirically say which airline is best for upgrades. At least for that year.