A person that is observing, its role in observational sciences and physical
A Delegate in an organization that is sent to observe and report on the proceedings of an Assembly or a meeting but that can not vote or otherwise participate.
An Aircrew Member of a (military) aircraft responsible for searching (usually visually) for intelligence, opposing forces and survivors of interest to the mission
A State Observer used in control applications. In most control systems not all state variables of the plant can be measured. If it is an Observable Plant the state can be estimated with the help of a State Observer . The estimated state is often used for Full State Feedback .
