Normally you are supposed to listen to your own plane and keep it in close enough so that if the engine quits, you will hear it slow down and then stop. There is a new computer that you can mount in the plane that uses sensors on board that will transmit all kinds of data such as engine rpm, altitude, speed, ect. to a box that is mounted on your transmitter but I just see it as another distraction from watching your plane and paying attention. [8D]