The term negative contact is used by pilots in responding to traffic identified for them by air traffic control. For instance, if you are using flight following on a cross-country trip, you will likely hear the controller call out traffic for you from time to time. "Cessna Two-Whiskey-Yankee, traffic 10 o'clock, four miles, southbound, four-thousand, five-hundred." If you do not see the traffic that the controller has pointed out to you, you would reply, "Negative contact." You might follow the response with a request for help in avoiding the traffic. The same term can be used by pilots to inform air traffic controllers that they were unable to contact air traffic control on a specific frequency though the term "unable" is more common, as when a new frequency is assigned during a handoff.