Originally posted by ITRADE:
2) RTFCs are NOT upgradeable. I have tried this before and have been rebuffed. In fact, on one attempt, a note was placed in my PNR explicitly stating that I should not be upgraded.
That's interesting. I was able to successfully upgrade ATL-CLT-DEN in January on an RTFC with upgrade coupons that I purchased right before the flight at the ATL ticket counter. It took the agent a while to process all the paperwork, but I had always assumed it was legal from reading posts about this subject on FlyerTalk.