According to the 2018 statistics on air travel from the International Air Transport Association (IATA), the number of passengers that flew via scheduled airline services was 4.1 billion worldwide. One thing should be noted regarding this statistic — the number 4.1 doesn’t mean that 4.1 billion individuals boarded flights across the world. Instead, it means that there were 4.1 billion passengers (for example, one person who flew four times in one year counts as four passengers).