In some of the above posts there have been references to pax being denied boarding because the passport was due to expire within six months. There are some countries, many actually, that have that requirement. The airlines are not the ones who determine this factor. What the airlines have to be careful about is not to let someone through who doesn't meet the requirements. The sad part is some of the countries don't always pay attention or heed the requirement. The issue lies when the person returns to the U.S. When immigration checks the passport they may make note if they notice a violation. Normally, you will not even know about it. The airline, however, is fined for the violation.
I used to work at the DFW airport and was aware of the fines. They were not cheap and we got nailed by it a couple of times. For example, Mexico requires a notarized letter from a parent if only one is traveling with their kid(s) under the age of 18. When I was flying to Mexico and aware of a single parent with kid(s) on the plane I would deliberately stand behind them when passing through immigration. More often than not, the immigration official didn't even ask for the letter. When it was presented the official sometimes looked at it, most that I witnessed, didn't even read it. There was a couple of times when those passengers were on my return trip. Again, I stood behind them to see what U.S. immigration would do. Sometimes, not always, the official asked for the letter, even though it wasn't needed for a U.S. citizen to return to the country.
While working at the airport I got to know some of the immigration officials. What I learned is they check a pax documents to see if everything was in order. If a discrepancy was found and verified the airline, which the person departed on, was fined. Therefore, as a ticket agent it was better to err on the side of caution and deny boarding if the documents were not in order or in question. It wasn't fun telling people they could not check-in because their passport was expired within six months or they lacked the notarized letter.
There are a couple of good websites to look up travel info: traveldocs, Timatic (the best one in my view and used by many in the travel industry - however, you have to pay for access to the website), and IATA Central, just to mention a couple. The ultimate place to contact is the airline. It is the airline that has to deal your documents. Avoid contacting the embassy. It was always annoying to hear people state they contacted the embassy for info and were told one thing only to find it was incorrect when they got to the airport. Most people working in an embassy are not airline employees nor immigration officials.
