Plane is the Python module running on the plane raspberry pi. It consists of driver classes to talk to sensors (gps, imu, etc), an on-board camera, and the pada drop servo. It also consists of a higher level communication class to publish sensor + image data to the server and send target gps coordinates to the pada.
See Codex's README/Releases on how to run Plane with everything else using Docker.
To run Plane on its own, you will need to ensure the server script is running (see How to Connect to Server) and that the rest of Codex's Poetry setup is complete, then it's simply python plane/plane.pys