What is the longest possible long-haul flight you could take? Or, in other words, which international airports are furthest apart?
• Ignoring the fact that Earth is very slightly oblate and taking its circumference to be 40,000 kilometres, the longest possible great semicircle – that is, a circle whose plane passes through Earth’s centre – is 20,000 km. The two major international airports I can find that come closest to this separation are Bogota, Colombia, and Jakarta, Indonesia, which are 19,829 km apart via a great circle.
There is a website for checking this sort of thing. The Great Circle Mapper () requires the and will plot the great circle routes and distances between them.
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Andrew Bristow, Chorley, Lancashire, UK
• Given that Wellington, New Zealand, is almost precisely the antipode of Madrid, Spain, and both cities have international airports, this must be a contender. The question then arises, given the slight asphericity of Earth, which great circle route would be the longest between the two.
Robin Bell, Canberra, ACT, Australia
• Presumably your correspondent wishes to know the longest scheduled flight. By private charter one can book planes to their maximum range, and with military in-flight refuelling this can be increased to 40,000 km – say, between the South African cities of Johannesburg and Pretoria via the poles. No civil aircraft has this capability, though.
The Boeing 777-200LR has a range of 17,445 km but with passengers and international regulations it is less. However, in a record-breaking publicity stunt in 2005, a specially prepared 777-200LR flight with passengers flew eastwards from Hong Kong to London – a distance of 21,601 km.
The longest scheduled flight is by Singapore airlines using an Airbus 340-500 from New York’s Newark airport to Singapore. This covers 15,345 km in about 19 hours.
Brian King, Barton On Sea, Hampshire, UK
• Both Bermuda and Perth, Australia, have international airports and are nearly precisely antipodes, although I doubt any airline offers a non-stop service between them.
Joe Dellinger, Houston, Texas, US