<P> An airline is a company that provides air transport services for traveling passengers and freight . Airlines utilize aircraft to supply these services and may form partnerships or alliances with other airlines for codeshare agreements . Generally, airline companies are recognized with an air operating certificate or license issued by a governmental aviation body . </P> <P> Airlines vary in size, from small domestic airlines to full - service international airlines . Airline services can be categorized as being intercontinental, domestic, regional, or international, and may be operated as scheduled services or charters . The largest airline currently is American Airlines Group . </P> <P> DELAG, Deutsche Luftschiffahrts - Aktiengesellschaft was the world's first airline . It was founded on November 16, 1909, with government assistance, and operated airships manufactured by The Zeppelin Corporation . Its headquarters were in Frankfurt . The first fixed wing scheduled air service was started on January 1, 1914, from St. Petersburg, Florida, to Tampa, Florida . The four oldest non-dirigible airlines that still exist are Netherlands' KLM (1919), Colombia's Avianca (1919), Australia's Qantas (1921), and the Czech Republic's Czech Airlines (1923). </P> <P> The earliest fixed wing airline in Europe was the Aircraft Transport and Travel, formed by George Holt Thomas in 1916 . Using a fleet of former military Airco DH. 4 A biplanes that had been modified to carry two passengers in the fuselage, it operated relief flights between Folkestone and Ghent . On 15 July 1919, the company flew a proving flight across the English Channel, despite a lack of support from the British government . Flown by Lt. H Shaw in an Airco DH. 9 between RAF Hendon and Paris--Le Bourget Airport, the flight took 2 hours and 30 minutes at £ 21 per passenger . </P>

When did the first commercial flight take place