Flight length

Aircraft do not necessarily follow the great-circle distance, but may opt for a longer route due to weather, traffic, to utilise a jet stream, or to refuel.

[4] David W. Wragg classifies air services as medium-haul being between 1,600–4,000 km; 900–2,200 nmi; short-haul as being shorter and long-haul as being longer.

Due to the COVID-19 pandemic and the impossibility of transit in the United States through Los Angeles International Airport, Air Tahiti Nui scheduled and operated in March and April 2020 Flight TN64 as a non-stop flight between Papeete and Paris-Charles de Gaulle, using a Boeing 787-9 and covering 15,715 km (9,765 mi; 8,485 nmi).

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 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 or fuel than the geographically shortest route.