Air traffic controllers in the United States coordinate more than 87,000 flights per day, according to the National Air Traffic Controllers Association. Approximately one-third of these flights, or 28,500, are scheduled flights.
According to the International Civil Aviation Organization, a United Nations agency that oversees the planning and development of international air transport, there are four types of aviation operations: commercial air transport, which governs flights that are conducted for remuneration or hire; general aviation, which includes all civil aviation flights other than scheduled flights and flights for hire; aerial operations, which are flights conducted for specialized services such as observation and patrol, search and rescue, or agriculture; and state flights, which include military, police and VIP flights.
A scheduled flight, according to International Civil Aviation Organization, is "an air service open to use by the general public and operated according to a published timetable or with such regular frequency that it constitutes an easily recognizable systematic series of flights which are open to direct booking by members of the public." Worldwide, more than 2.29 billion passengers per year travel via scheduled air services.
In the United States, scheduled air services are regulated by the Federal Aviation Administration. In the European Union, the European Aviation Safety Agency oversees aviation operations. Each individual EU member also has its own governing body, such as the Civil Aviation Authority in the United Kingsom.
The FAA also regulates the issuance of operating certificates to commercial carriers. The operating certificate verifies that the airline or carrier can operate safely and comply with the regulations and standards of the FAA.
Scheduled air services include domestic and international flights, and are conducted by so-called "legacy carriers" and low-cost carriers. Legacy carriers are large airlines that generally offer a first and/or business class option, frequent-flier programs and alliance perks. Examples include United Airlines, American Airlines and Delta Air Lines in the United States, and British Airways, Air France and Lufthansa in Europe. Low-cost carriers, or budget airlines, offer lower fares and usually charge extra for baggage handling, food and beverages and priority boarding. Examples include JetBlue and Spirit Airlines in the United States and EasyJet and Ryanair in Europe.
