Negative Contact

Used by pilots to inform Air Traffic Control (ATC) that: 1) Previously issued traffic is not in sight. It may be followed by the pilot's request for the controller to provide assistance in avoiding the traffic. 2) They were unable to contact ATC on a particular frequency. (FAA4)

Used by pilots to inform ATC that:

a. Previously issued traffic is not in sight. It may be followed by the pilot's request for the controller to provide assistance in avoiding the traffic.
b. They were unable to contact ATC on a particular frequency.