"When tower or center tells you about other traffic and you do not see the traffic, what is the best response? There are so many variations out there. Also, what is the best response when you finally spot the traffic? What does ATC want to hear? " - Mark J.
“The AIM Pilot Controller Glossary recommends two phrases:
Traffic in Sight – used by pilots to inform a controller that previously issued traffic is in sight.
Negative Contact – used by pilots to inform ATC that 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.
It can help the controller and other aircraft if you specify the type when reporting the traffic. For example, if you say twin Cessna in sight and the controller is pointing out a single engine, it lets him or her know that you are not looking at the correct aircraft.
In addition, including the phrase have him on TCAS or TIS doesn’t really help much. It lets the controller know you are looking but does not relieve the controller of the requirement to establish visual contact.”