Did you travel to Greece without a Schengen visa?
use the document posted to this link: forums.immigration.com/showthread.php?268046-documents-you-need-to-enter-or-leave-the-USA
It is an official DHS document.
No, I did not have any visa on my RTD, so the potential risk should be I was refused to fly to Greece, but I had no problem at all for this part. (Greece did require Schengen visa for RTD, I checked the website of Greek Embassy.)
Like I said earlier, there is supposed to be no border or passport control within Schengen area, so I am free to travel everywhere (Schengen country) in principle as long as I entered Germany. The only thing to my surprise is some officers at Berlin SXF airport waited at arrivals to unofficially check passengers' passport and visa, but I guess that is because the flight is from southern Europe and they try to screen some illegal immigrant out.
These things happen. Its your responsiblity to print out things that says you can travel with a RTD. For example, I used to take a letter from German Embassy saying RTD doesn't need a visa...or a printout from USCIS website that RTD can be used as a passport.
Only way you can educate people is by educating them yourself. I would write a strong worded letter to US Airways and you should expect to be compensated(like a free ticket).
Just because you, on a personal level make the assumption that "there is supposed to be no border or passport control within Schengen area" doesnt mean that there is no border patrol. I really don't know why you are "surprised" when you see border patrol checking visas and passports even within the EU countries. It has been stated many times in this forum that if you think you are being clever and sneaky and arrive in Germany and can think you can go anywhere without being stopped and scrutinized, you are sadly mistaken. You tried to circumvent the rules of Greece which explicitly state you need a visa to enter with RTD which was a big mistake. You entered Greece because you got lucky and no one bothered to check from Germany to Greece. You got into trouble when you tried to go back to Germany from Greece. A visa allows you entry AND exit from a country. Try overstaying your visa when you get one and see if any European countries just let you leave without any hassle. If you had gotten a Greek visa like you were supposed to and not tried to sneak in via Germany without a visa, you would not have had any of these issues. The airline agent would have seen your Schengen visa (Greek visa) in your RTD and you would have had NO problems going back to Germany. There would have been NO question by anyone that the Greek embassy/consulate had put a visa in a non-approved travel document.
You may have a valid complaint with US Airways and I would absolutely complain regarding that matter if it was me.
I have to agree with ASSYLEE. I still think you have a valid grievance against US Airways, no doubt about that, but you shouldn't knowingly and intentionally break other countries' immigration laws just because there are fewer or no border checks. Remember, you are travelling with a United States Travel Document, and when you engage in illegal actions while abroad, you are encouraging those countries to drop visa free travel benefits to all US RTD holders, as well as making the US govt. look bad.
US Airways replied they would address this issue internally with the local manager and provided me with a $200 Voucher. I think I might ask them to share this issue with as many airports as they can, so that it could benefit the future RTD holders.