Logged on or not has nothing to do with it. AA is storing (and analyzing) all of your behaviour on aa.com based upon the browser cookie on your hard drive. The cookie is there whether or not you are logged on to aa.com. Of course they will also track activity by your AAdvantage number, but they don't need you to logon in order to track you.

The cookie itself stores very little information. It's just a unique identifier that is stored on your hard drive. And every time you do anything on aa.com, its software asks your browser if there's an aa.com cookie present on your system. If there is, the browser supplies it and whatever you do in that session is recorded, tagged to your cookie, and stored at an AA data center. This is not unique to the transportation industry and it's perfectly legal. Some would say that getting as much as they can for every fare is capitalism at its finest.

It is no problem at all for AA to individually analyze every traveller's habits and generate customized emails or "tweak" the fares each person is shown. Grid computing in a private cloud can give AA the equivalent of 500,000 - 1,000,000 powerful servers all working on these problems simultaneously. For not very much expense, either.

Case in point: tonight on ITAsoftware I found a really nice fare for a trip that my wife and I want to take very soon. I went to aa.com, put in the flight numbers and the price was about 20% higher. Both sites claim to show all-inclusive prices...

So I deleted all the cookies from my computer, went back to aa.com, requested the same flights, and lo and behold, this time I was given the same fare as ITA had given me. Without that cookie, aa.com had no way to tie my current reservation to prior activity. Needless to say, I didn't sign on to my Aadvantage account until after I had the fare. Now there is a new aa.com cookie on my computer, which will have a different identifier than the old one.

Was AA using the presence of an aa.com cookie on my laptop to give me a hgher fare? There's no way of knowing, really. But this is a recurring topic in the IT industry - you almost always get a better deal on-line right after you delete all the cookies from your system. Okay, you'll have to logon to FlyerTalk again (and FB, Twitter, etc.), but perhaps a small price to pay.

Coincidence? You decide.