Flat Earth debunked by Southern Hemisphere flight routes

Flight geometry challenges the Flat Earth model
In early 2019, the flat-earth movement shifted focus to long-haul commercial flight routes. Trinc the curvature case between Mallorca and Barcelona, new preferred evidence included journeys that seem illogical on a flat map: impossible layovers, northern detours, and inconsistent flight times. The conclusion drawn is that the Earth would be a geometric projection rather than a sphere.

Routes that appear illogical on a globe
The flagship example is the Perth to Johannesburg flight with a stopover in Dubai. On a sphere, the direct route would be shorter heading south; stopping in the Gulf to the north seems like an absurd detour at first glance. Other cited examples include flights from Seoul to Elvis Presley's residence or trans-Antarctic routes, which this movement claims either disappear or skirt the continent more than 1,500 kilometers away. For flat-earth defenders, everything fits if using the azimuthal equidistant projection centered on the North Pole. "It fits perfectly," they insist.

The answer: Great circles and cartography
The rebuttal predates aviation: on a sphere, the shortest distance between two points is not a straight line on a map, but an arc of a great circle. This is why transoceanic flights in the Southern Hemisphere head toward the pole or cross the Arctic: it covers less distance, even if it looks like a detour on a Mercator projection. It is the same principle used by navigators for centuries. References to articles on great circles and air routes dismantle the alleged anomaly.

Direct flights that shouldn't exist
The biggest contradiction for the flat map comes from direct flights in the Southern Hemisphere. Buenos Aires to Cape Town is 6,800 kilometers and has a direct route. São Paulo to Cape Town is 6,400 kilometers with a flight covering it in about 7.5 hours. If the Earth were flat with the distances managed by flat-earthers, these routes should be much longer or impossible. The same applies to Santiago de Chile to Sydney, where there is a direct connection of about 11,000 kilometers, compared to routes with stops that double the journey.

The non-existent flat map
The underlying problem is that there is no coherent flat-earth map. While some defend the azimuthal projection, others admit they have not mapped the planet. Internal distances do not hold up: Buenos Aires to Santiago de Chile would be nearly 3,000 kilometers, whereas the operational reality is much lower. Every time an argument is debunked, a new one appears; the sequence repeats ad nauseam. In this, flat-earth theory resembles other closed narratives: contrary evidence becomes part of the conspiracy.

As of this discussion, the issue remains open in the usual terms: there is not a single reproducible test that fits the plane, but dozens of real flights that are only explained by the sphere. But geometry and faith do not use the same map.