You can start even before you get on the plane. When you are still waiting at the airport, ask the man next to you, "Where are you going?" or "Are you going to New York too?" Be engaging.
Once you are on the plane, you can approach his friends first. If he is flying with a female colleague, that's even better, because you can say to her, "I like your scarf/necklace/jacket" and her reaction is guaranteed to be good. If he is flying with a male friend, simply ask for his male friend's opinion on which magazine to read or which show to watch on the plane - this leads to interesting content in the magazine or on the show that you can further discuss. The main idea is: simply talk to his friends about something interesting, and then find an opportunity to approach him later on (e.g., engage him in your conversation with his friend). This is called "gateway" technique.
When you get off the plane, on your way out you can walk close to him. If he stops at the information desk, you also stop at the information desk and ask a question. Then you can discuss this question with him too. If there is no information desk along the way, you simply ask him a question such as "Do you know any cool places to go in New York/Los Angeles/etc.?" He will definitely speak to you because he has to answer your question. If his answer is "No, this is my first time here", then you can say, "I hear that XYZ is a cool place, but I'd like to know more cool places." Then you can talk to him about XYZ that can also interest him. By talking about XYZ, you are planting a seed in your communication with him - implying that you two can visit XYZ in this new city. If you feel that he is going to leave the conversation soon because he is walking towards a different direction, say this to him, "If you can give one piece of advice about life, what would that piece of advice be?" I'm sure he will be intrigued.
If you are a flight attendant, whenever there is a chance, you can ask him, "John, would you like some recommendations about where to go and what to do in New York/Los Angeles/etc.?"
Try these tips, and let me know how it goes :-)