In this lesson, you will learn how to travel internationally with your drone. You will need to fill out paperwork.
Download the US Customs Form 4457
International airline travel is a bit more involved than just domestic travel, because you must pass between a customs and immigration's checkpoint. If you are based in the United States and you travel internationally with a drone, I would recommend completing paperwork before you depart that proves that you didn't purchase the drone during your trip.
When you return to the United States you may be asked to prove that your equipment was not purchased abroad. I'll provided a link to the U.S. customs form 4457, which is a certificate of registration for personal effects taken abroad. Drones are becoming common enough that most security and custom agents are becoming familiar with them. I did travel to Dubai a couple a of years ago with a Phantom 2, and their custom agents weren't sure exactly what this drone was that I was carrying and they held me for about 15-20 minutes while they inspected the drone and the attached GoPro camera, and if this happens to you just make sure to stay calm and be polite.
The agents may ask you to remove the drone from the case and explain and show the parts and maybe explain how it works. That's what happened in my case and once they determined that I wasn't a threat they cleared it with their supervisor and then they sent me on my way. Since then I have traveled to probably a dozen other countries and have never been stopped, but make you're polite and courteous and you should have no issues.
Making sure that your batteries are in good condition and stored in your carry on luggage is probably even more important for international flights. These flights are much longer and they cruise at much higher altitudes.
This will allow for more chance for your battery to swell and catch fire. Before you travel it is also a good idea to research the drone laws of where you are going to be going. Some countries and cities have strict laws about where you can fly your drone. Be respectful and follow the rules and you should stay out of trouble.