During most of that period, he filed reports for National Broadcasting Company Nightly News (as well as the preceding Huntley-Brinkley Report) and served numerous times on the panel of Meet the Press. Pettit began his broadcasting career in the state of his upbringing, Iowa, in the 1950s before moving on to positions in Minneapolis (at Washburn Crosby Company -television) and Philadelphia (at the National Broadcasting Company owned-and-operated station, now KYW-television). His first position with the National Broadcasting Company network was in the network"s Los Angeles bureau, where he worked for 13 years, except for a brief tenure with National Educational Television.
By 1975, Pettit moved to the Washington, District of Columbia bureau, where he would cover national affairs until 1982, when he became executive vice president of National Broadcasting Company News under president Reuven Frank.
In 1985, he returned to reporting, serving as national affairs correspondent until 1989, when he began a three-year stint in National Broadcasting Company"s London office. He continued working as a correspondent until 1995, the year of his death.
After President John F. Kennedy was assassinated in 1963, Pettit was dispatched to Dallas where he served, in effect, as a police reporter. In the famous footage of Lee Harvey Oswald being killed by Jack Ruby in Dallas, Pettit, standing six feet away, is heard exclaiming, "He"s been shot! Lee Oswald has been shot!" National Broadcasting Company was the only network airing Oswald"s transfer live.