In aviation, the flight length is defined as the distance of a flight.
Eurocontrol defines short-haul routes as shorter than 1,500 km (810 nmi), medium-haul between 1,500 and 4,000 km (810 and 2,160 nmi) and long-haul routes as longer than 4,000 km (2,200 nmi). The Association of European Airlines defines Long-haul as flights to Americas, sub-Saharan Africa, Asia, Australasia and medium haul as flights to north Africa and Middle East. Air Berlin defines short and medium-haul as flights to Europe/northern Africa and long-haul to the rest of the world. Air France defines short haul as domestic, medium haul as within Europe/North Africa and long haul as the rest of the world.
Virgin Australia defines domestic flights as within Australia, Short Haul to South East Asia/Pacific and Long Haul to Abu Dhabi or Los Angeles. The Hong Kong Airport considers destinations in North and South Americas, Europe, the Middle East, Africa, Southwest Pacific and the Indian Subcontinent Long Haul and others are Short Haul. Japan Air Lines defines routes to Europe and North America as Long haul and the other as short haul.
American Airlines define medium/short-haul flights as less than 3,000 mi (2,600 nmi; 4,800 km) and long haul as more than that and New York to Los Angeles or San Francisco: 2,475–2,586 mi (2,151–2,247 nmi; 3,983–4,162 km); the same distinction for United Airlines between long and short haul.
Lufthansa defines its fleet as long-haul for wide-body aircraft such as the Airbus A330/A340, A350 and A380, or Boeing 747, medium-haul for narrow-body aircraft like the A320 and B737 families, and short-haul for regional jets like the Embraer E-Jets or the Bombardier CRJ-900. Thomson Airways defines the Boeing 737 as a short and mid-haul airliner while the Boeing 767 and B787 as long haul.
Delta defines its Boeing 717, MD-88 and MD-90 as short-haul domestic aircraft, Boeing 757, Boeing 737, Airbus A319 and A321 as long-haul domestic and Boeing 777, B767, B747, Airbus A330 and transoceanic Boeing 757 as long-haul.
While they are capable of flying further, long-haul widebodies are often used on shorter trips: 40% of A350 routes are shorter than 2,000 nmi (3,700 km), 50% of A380 flights fall within 2,000–4,000 nmi (3,700–7,400 km), 70% of 777-200ER routes are shorter than 4,000 nmi (7,400 km), 80% of 787-9s routes are shorter than 5,000 nmi (9,300 km), 70% of 777-200LRs flights are shorter than 6,000 nmi (11,000 km) and 777-300ERs flights are evenly distributed across its range.
The Loganair Westray to Papa Westray route is the shortest commercial flight in the world over 2.8 km (1.7 mi) in two minutes scheduled flight time including taxiing.
The longest commercial flight is the Qatar Airways flight between Auckland and Doha, covering 14,535 km (7,848 nmi) with a Boeing 777-200LR. The longest ever was Singapore Airlines Flight 21 from Newark to Singapore, covering 15,343 km (8,285 nmi) in 18.5 hours using an Airbus A340-500.
The absolute distance between two points is the great-circle distance, which is always the shortest geographical route. In the example (right), the aircraft travelling westward from North America to Japan is following a great-circle route extending northward towards the Arctic region. The apparent curve of the route is a result of distortion when plotted onto a conventional map projection and makes the route appear to be longer than it really is. Stretching a string between North America and Japan on a globe will demonstrate why this really is the shortest route despite appearances.
The actual flight length is the length of the track flown across the ground in practice, which is usually longer than the ideal great-circle and is influenced by a number of factors such as the need to avoid bad weather, wind direction and speed, fuel economy, navigational restrictions and other requirements. In the example, easterly flights from Japan to North America are shown taking a longer, more southerly, route than the shorter great-circle; this is to take advantage of the favourable jet stream, a fast, high-altitude tail-wind, that assists the aircraft along its ground track saving more time and fuel than the geographically shortest route.
Air time is the elapsed time that the aircraft is airborne, regardless of what time-zone the flight began and ended in.
Schedule time is the difference between the scheduled local time at the origin and the scheduled local time at the destination and usually differs from the actual time in the air as it is affected by the local time zones. Local clock time flying westward, or "chasing the sun", is slowed, while local clock time flying eastbound is sped up. However, flights over the International Date Line located at approximately 180o E in the Pacific will subtract 24 hours from the schedule time going eastwards and add 24 hours going westwards. For example, the eastward flight shown in the example from Japan to North America will have a scheduled time of arrival earlier than the departure time, while from North America to Japan the flight will take a whole day longer by local time; the actual flying time in both cases being the same or similar.
The flight classification as long-, medium- or short-haul is classified according to the elapsed air time, not the scheduled time difference.