Abstract: An apparatus for visually communicating to a pilot in the cockpit of a parked aircraft the status of a preconditioned air (PCA) unit associated with the gate has an electrically controlled PCA indicator box positioned so that it is visible to the pilot in the cockpit. The PCA indicator box has a first appearance when the preconditioned air unit is not operating and a second appearance when the preconditioned air unit is operating. A method of assisting aircraft operators to reduce fuel costs and emissions of an aircraft parked at a gate includes mounting to the gate an electrical PCA indicator and electrically coupling it to a preconditioned air unit at the gate.