Walkie talkies do work in large, enclosed vehicles such as airplanes and cruise ships. They may have trouble with dense cabins in the middle of ships, but many people use them to keep in touch with their family. As for aircraft, they might work within the plane, but it’s very illegal. You won’t be able to communicate with people outside the plane because the plane’s body will function as a Faraday cage and block the signal. My recommendation is to take out the battery, store the it in your luggage, and save it for the mountains!