TRAFFIC IN SIGHT. Used by pilots to inform a controller that previously issued traffic is in sight. (See NEGATIVE CONTACT.) (See TRAFFIC ADVISORIES.)
NEGATIVE CONTACT. 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.
After working radar for ten years I can say that offering traffic info is the last item on the list of things to do. Also, air time is pricey so say the most with the less words possible. “Looking” would work in my book. Think of it from a Controllers side, if there was in incident, at least he/she made an effort to warn you so his/her back end would be protected if there was a review. David Dressler
ATC doesn’t care if you have the traffic on a TCAS type system because it doesn’t change anything on their end. Once you have communicated to them that you have traffic in sight, then they can issue commands such has maintain visual separation.