Over the last 6 years I have flown just enough to maintain a Silver status for USAir. This is the lowest rung on the ladder for frequent flyers at USAir. The last two years, I have been complimentarily upgraded to 1st class on 64% of the flights where 1st class was available. I know this because USAir sends me a monthly statement and this stat is listed. On flights where I didn't receive the upgrade, the 1st class cabin was full. I was lucky(?) enough to qualify for Gold status this December. The perks are a bit nicer. I'm running 100% on the first 6 flights for upgrades since the status took hold.
I achieved Gold (the lowest rung) for American for all of 2013 and again for 2014. I had zero complimentary upgrades. They did deposit four, 500 mile upgrade certificates in my account. They can be used to request upgrades, with no certainty, on flights that don't exceed the miles of the certs. The information that I've read on here leads me to believe that the reason for zero upgrades with American is because they have a zillion members in the levels above Gold that score any and all upgrades. Interestingly enough, I flew on Dec 29 and Dec 31 with American. In both instances, the 1st class cabin was empty. On the 29th, there was one couple using two of the 16 (I think) seats. On the 31st, I used two certificates to upgrade. I was one of just 3 people using any of the 24 seats in 1st class.
My question is twofold..... 1) Was my experience the norm with American? Did they leave 1st Class cabins empty instead of complimentarily upgrading frequent flyers? 2) When the two airlines are merged for good, will the complimentary upgrade be a thing of the past for all frequent flyer levels?