When were passenger airplanes invented?

Barely a decade after the Wright brothers' flight, Russian engineer Igor Sikorsky unveiled the Ilya Muromets in 1913, a four-engine aircraft with an enclosed cabin, seats, heating and even a lavatory, designed from the outset to carry passengers. World War I turned it into a bomber before it could be exploited commercially. In the United States, the St. Petersburg-Tampa Airboat Line launched the first scheduled service with a timetable and fare on January 1, 1914: a Benoist XIV crossed Tampa Bay in 23 minutes with a single passenger, who paid five dollars. It operated for four months and carried more than 1,200 people.

Passenger air transport as a stable business was born when the war ended, when there was a surplus of aircraft and pilots. In 1919 the first European international routes began, between Paris and London, and that same year KLM was founded, the oldest airline still operating under its original name. The aircraft were converted bombers or wood-and-fabric biplanes such as the De Havilland DH.16, with four seats and an enclosed cabin. Flights were noisy, cold and expensive, reserved for a minority.

The decisive leap came in the 1930s with all-metal monoplanes such as the Boeing 247 (1933) and, above all, the Douglas DC-3 (1935), which combined speed, reliability and 21 seats, allowing an airline to make money from passengers alone for the first time. Pressurization on the Boeing 307 (1938) and the arrival of the commercial jet with the de Havilland Comet in 1952 completed the transformation toward mass air travel.