began serving Fort Smith with Douglas DC-3 aircraft flying a daily round trip routing of Denver-Colorado Springs-Pueblo-Amarillo-Oklahoma City-Tulsa-Muskogee, OK-Fort Smith, AR-Little Rock-Memphis, TN and later operated Convair 340 and Convair 440 propliners as well as Lockheed L-188 Electra turboprops and British Aircraft Corporation jets followed by Boeing jetliners into the airport. By the early 1950s, Braniff had entered into an interchange flight agreement with Eastern Airlines to extend its Denver-Memphis route south and east to Birmingham, AL, Atlanta, Tampa, and Miami with these flights featuring no change of plane through service. In 1952, four engine Douglas DC-4 aircraft were flown on the interchange service with a daily routing of Denver-Amarillo-Oklahoma City-Tulsa-Fort Smith-Little Rock-Memphis-Birmingham-Atlanta-Tampa-Miami with the return flight from Miami making an additional stop in Colorado Springs before arriving into Denver. By 1966, the Braniff-Eastern interchange service was being operated with a Convair 440 propliner on a daily roundtrip routing of Denver-Colorado Springs-Amarillo-Oklahoma City-Tulsa-Fort Smith-Little Rock-Memphis-Birmingham-Atlanta. In 1967, the two airlines were continuing to operate this interchange service between Denver and Atlanta with Lockheed L-188 Electra turboprops; however, these flights were no longer serving Fort Smith by this time. In 1965, Braniff International introduced the first scheduled passenger jet service into Fort Smith with British Aircraft Corporation BAC One-Eleven twin jets with nonstop flights at various times during the mid and late 1960s to Little Rock, Shreveport and Tulsa as well as direct no change of plane jet service to Chicago, Dallas, Kansas City, Memphis, Minneapolis/St. Paul, New Orleans, Oklahoma City, Omaha and other destinations. In the spring of 1966, the airline was serving the airport with two BAC One-Eleven jet flights a day on a daily roundtrip routing of Minneapolis/St. Paul-Omaha-Kansas City-Tulsa-Fort Smith-Shreveport-New Orleans in addition to operating services on other routes from Fort Smith with Convair propliners. By the summer of 1968, Braniff was operating six flights a day into the airport including a daily roundtrip BAC One-Eleven service with a routing of Chicago O'Hare Airport-Kansas City-Tulsa-Fort Smith-Shreveport-New Orleans, a BAC One-Eleven flight operating one way Memphis-Little Rock-Fort Smith-Tulsa-Oklahoma City-Dallas Love Field, a BAC One-Eleven service operating one way Amarillo-Oklahoma City-Tulsa-Fort Smith-Little Rock-Memphis, a Lockheed L-188 Electra turboprop flight operating one way Memphis-Little Rock-Fort Smith-Tulsa-Dallas Love Field-Fort Worth Greater Southwest International Airport-Houston Hobby Airport-Corpus Christi, and a Lockheed L-188 Electra turboprop service operating one way Houston Hobby Airport-Dallas Love Field-Tulsa-Fort Smith-Little Rock-Memphis. During the 1970s Braniff operated Boeing 727-100