I'd like to hear more about what the original poster is looking for. In order for IR to work, the "lost" object needs to be warmer than the background. If he's looking for something that is already lost, it's gonna cool down before he gets up in the air.

I would expect that an amateur would have a tough time flying real time by IR. Maybe he's planning to have someone fly the plane and somebody else monitor the video feed.

I know it's off topic for the beginner forum, but I enjoy hearing different concepts for using RC planes, even if many of them are dangerous or illegal