Supplemental airlines were originally called Non-Skeds - short for non-scheduled i.e. charter airlines. Following WW2 and during the 1950s there was a surge in new airline startups using war surplus aircraft and pilots. The CAB and the scheduled airlines took a dim view of these airlines both from a safety perspective and because of their bending the rules and effectively competing against the Trunk airlines. They were so successful in fact that they were the primary driver for the introdution of coach fares by the majors. Gradually the CAB and economics drove most of the hundreds of players from the market though the CAB had admitted they played a role since 1955 and began to provide short-term supplemental air licenses. In 1959 the CAB gave certificates of public convenience and necessity to 23 of 53 applicants with 11 only getting rights for 2 years. These airlines could operate a maxiumum of 10 round services per month between any two destinations to individually ticketed passengers and weigh-billed freight. The 12 airlines 'whose qualifications were clear and strong' and got 5 year licenses were:
American Flyers Airlines
California Eastern
Capitol Airways
Coastal Cargo
General Airways
Johnson Flying Service
Overseas National Airways
Southern Air Transport
Standard Airways
Stewart Air Services
Transocean Air Lines (TALOA)
World Airways
Trans International Fleet
The other 11 included Modern Air Transport. Three years later in 1962 the CAB gave interim operating certificates to only 14 Non-Skeds hence known as supplementals, down from 32 that had existed the year before. These included:
Aaxico Airlines
American Flyers Airline
Capitol Airways
Johnson Flying Service
Modern Air Transport
Overseas National Airways
Purdue Aeronautics
Trans International Airlines (later Transamerica)
Saturn Airways
Southern Air Transport
Standard Airways
United States Overseas
World Airways
Zantop Aviation
During the 1960s the supplementals gained permanent licenses and found good business working for the US Government supporting the war in Vietnam. Most were able to replace their prop-liners with new jets and continued relatively unmolested through the 1970s. Several new charter airlines, as they came to be known, began service during this time (Universal, ATA, Aero America, Rich international) to join the ranks of the survivors thinned out by mergers. Deregulation saw several attempt entry into the scheduled markets, in particular Capitol Airways with low-cost transatlantic services, but most survivors became mainly freight airlines if they survived at all.