27 December 2009

Antipodes

I was recently involved in a discussion about the shortest distances between various airports in East Asia and South America. Being on opposite sides of the world, many airport pairs in the two continents cannot be served non stop with existing airliners.

The Boeing B777-200LR (17,395 km range) and Airbus A340-500 (16,700 km range) come close but the economics of ultra long-haul, point-to-point routes means that they struggle to be profitable. Therefore the question arises as to what intermediate points make sense to airlines and travellers. For example, to what extent does Auckland (AKL) make sense as an intermediate point for travel between the two continents?

The Great Circle Mapper web site is a great help in supporting such discussions (see previous post) but also useful is the Antipodes Map web site which identifies the exact opposite side of the world to any point on the globe. The Wikipedia entry for Antipodes has a couple of maps that illustrate this.

The world is not exactly spherical. The distance around the Earth at the equator is 40,075 km. The distance around the Earth through the poles is 40,008 km. Therefore the theoretical maximum great circle distance between any two airports is 20,038 km.

Of course, considerations such as times from alternative airports in the event of an engine failure, prevailing winds, connecting times and visa requirements will also influence airlines and travelers decisions.

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