Lennonumerointi

Lennonumerointi, also known as flight numbering, is a system used by airlines and air traffic control to identify and track individual flights. Each flight is assigned a unique alphanumeric code, typically consisting of a two-letter airline designator followed by a one- to four-digit flight number. For example, "BA283" represents a British Airways flight numbered 283.

The airline designator is usually derived from the airline's IATA (International Air Transport Association) or ICAO (International Civil Aviation Organization) code. IATA codes are typically two characters, while ICAO codes are three. Flight numbers are assigned by the airlines themselves and are often sequential for a given route, though they can change seasonally or due to operational reasons.

This numbering system is crucial for operational efficiency and safety. It allows for clear communication between pilots, air traffic controllers, airline operations centers, and passengers. Flight numbers are used in flight plans, manifests, scheduling, and passenger information systems. They help in managing airspace, coordinating takeoffs and landings, and ensuring that all parties involved have accurate information about each flight. Some airlines also use specific number ranges to denote different types of flights, such as domestic or international services, or to indicate a codeshare partnership.