A system has a contactless user-interface through which a user controls a functionality of the system. The contactless user-interface has a detector sub-system and a user-feedback sub-system. The contactless user-interface has an alert mode and a control mode. In the alert mode, the user-feedback sub-system has a display monitor to provide a visible acknowledgement to the user, in response to the detector sub-system having detected the presence of the user within a an alert range. The contactless user-interface transitions from the alert mode to the control mode in response to the detector sub-system detecting an initialization gesture of the user. In the control mode, the contactless user-interface controls the functionality in response to the detector subsystem detecting a control gesture of the user. The visible acknowledgement is made to mirror the movements of the user.