As is typical with the backpacker style, you only fly to a continent, then you find your way around with various other less expensive modes of transportation to neighboring countries. However, this poses a problem when you are flying to Thailand and plan on training/busing it to Vietnam, Laos, Malaysia, China, or Burma. Having dealt with this problem just two days ago, I was shocked that in my research before and after, I had never heard of this problem nor found a clear solution to it.
Two Couchsurfers I hosted also mentioned having this problem when flying into Vietnam. Sorry, I should clarify, the problem is the airline will not let you onto the flight into Thailand without you already having confirmed ticket out of Thailand. The reason is because the airline assumes the financial responsibility and risk of deporting you in the event that you are denied entry into the country because Thai visa laws require that you have a confirmed ticket. The truth is that the Thai customs official do not care about this requirement, especially if you are from a Western English speaking country, but because of the financial risk for the airlines, they will refuse to board you. And because this is an airline problem, the solution may vary from airline to airline.
What can you do about this?
The safest solution is to get a Thai visa ahead of time, but of course if you didn’t know about this until you are at the check in counter, then you can’t exactly do that. The next safest, but most expensive option is to simply buy the cheapest return flight even though you know you will not use it. And yes, it has to be a flight because it is impossible to buy a train or bus ticket outside of the country. The best, but has small risk, option is to check into your flight online that way you skip the pesky questions. The reason this has small risk is because I’m not an expert in airline regulations and cannot confirm that they will not somehow discover that you don’t have an onward flight. Now if you have to check in because you have bags, you can try to sign a waiver assuming financial responsibility and risk in case you are denied entry, but I have never done this, only read about it online.
In my situation, we didn’t check in online simply because we didn’t, but luckily we had a layover in Manila. They gave us trouble at the check in counter and finally they said they would let us go to Manila, but we still needed an onward flight to get to Bangkok. Having 3G, but no flash capable devices, we called my parents who checked in online for us and emailed me the boarding passes which were successfully downloaded onto my phone just second before the stewardess told me to turn off my electronic device. Once in Manila, we checked in at the he transfer desk with our electronic boarding passes, no questions asked.
We successfully circumvented the system! Hoorah!