A flight from Sydney to Santiago turns an abstract argument about Earth’s shape into something measurable: two airports, a journey time and an aircraft with known capabilities. That is why this route repeatedly appears in flat Earth discussions. It offers a more demanding question than whether a line looks strange on a map: how far must the aircraft travel, and can it cover that distance in the available time?
In “How do Flights Like Sydney-Santiago Work on Flat Earth?”, Eric Dubay challenges the claim that southern long-haul flights rule out a flat Earth. His published description acknowledges an approximately thirteen-hour direct flight, then disputes the conclusion drawn from comparing it with longer journeys through the United States. Here, we examine that argument through explicit predictions rather than competing impressions.
Start with the flight that actually exists
The first question is whether Sydney–Santiago is merely an itinerary assembled from connecting flights. It is not. Qantas describes a direct Sydney–Santiago service taking approximately twelve hours and twenty minutes. Its July 2025 travel-agent information gives the same approximate duration.
That does not mean every departure takes exactly that long. Weather, operational routing and delays matter. Nor should a promotional duration replace the records of a particular flight. Nevertheless, the airline’s published service establishes a concrete starting point consistent with the roughly thirteen-hour journey discussed in Dubay’s description.
Connecting through another continent creates a different journey. Comparing total itinerary durations without separating flying time from airport waiting time can mislead. On that narrow point, skepticism is reasonable. But removing layovers from the argument does not remove the distance problem.
Make both maps predict a number
For a transparent comparison, use approximate airport coordinates: Sydney at 33.9461 degrees south, 151.1772 degrees east; Santiago at 33.3930 degrees south, 70.7858 degrees west. A spherical calculation with a mean Earth radius of 6,371 kilometres gives a shortest surface distance of approximately 11,340 kilometres.
This is a model calculation, not a claim that every aircraft follows the shortest possible track. A more precise ellipsoidal calculation differs slightly. Air Miles Calculator publishes both approaches, placing the airports about 11,340 kilometres apart on a sphere and about 11,363 kilometres apart on an ellipsoid.
Now consider the familiar north-polar azimuthal-equidistant map, interpreted as a literal physical plane. Keep its standard radial scale: distance outward from the North Pole follows angular distance from the pole. Sydney and Santiago then sit roughly 13,780 and 13,720 kilometres from the centre. Their smaller longitude separation is approximately 138 degrees.
Applying ordinary plane geometry to those positions gives a straight-line separation of approximately 25,680 kilometres. That is already the shortest route between those two points on that plane. Adding a bend, an airway or a diversion would increase it.
The comparison therefore produces a substantial difference: approximately 11,340 kilometres versus 25,680 kilometres. The flat-map distance is about 2.26 times as large. This tests one specified flat Earth layout, not every imaginable alternative. Any replacement layout would need its own coordinates and scale before it could make a competing prediction.
Why a familiar flat map creates this discrepancy
A flat map is not automatically a flat Earth model. It may be a mathematical representation of a curved surface. Treating its appearance as physical geography changes what its distances mean.
The U.S. Geological Survey explains that map projections preserve different properties and distort others. In an equidistant projection, accurate distances apply along particular lines, such as those radiating from the chosen centre. They do not necessarily apply between arbitrary pairs of points.
For the north-polar version, this distinction becomes especially important in the south. Distances outward from the pole can be represented consistently while separations around southern latitude circles become greatly stretched. Drawing the shortest-looking line on that sheet does not turn its distorted scale into the physical distance an aircraft flies.
This is also why a curved flight track on a rectangular world map is not, by itself, evidence of an inefficient route. The projection can make a short surface route appear curved. The useful comparison is numerical distance under stated assumptions, not visual straightness.
Thirteen hours puts the geometry under pressure
Using thirteen hours for both models keeps the arithmetic simple and follows the approximate duration in the video’s description. Covering 11,340 kilometres in that time requires an average ground speed of about 872 kilometres per hour. Covering 25,680 kilometres requires approximately 1,975 kilometres per hour.
Those figures describe average progress over the ground. They are not direct readings of speed through the surrounding air. Even so, they show the scale of the challenge: the literal polar-map interpretation requires more than twice the average ground speed.
For context, Qantas lists the Boeing 787’s average cruise speed as Mach 0.85. Its 2020 aircraft data book gives 903 kilometres per hour for the 787-9. These specifications are contextual benchmarks, not a reconstruction of a particular flight’s performance.
The spherical distance sits in the ordinary long-haul operating range. The literal flat-map distance demands a much more extreme explanation. A successful alternative must supply that explanation quantitatively, with measured conditions rather than an unspecified possibility.
Winds matter, but they must be measured
Jet streams can make a substantial difference to flight times. NOAA explains that these strong upper-level winds generally flow west to east and can help aircraft travelling in the same direction. This is one reason opposite-direction journeys need not take equal time.
However, mentioning a jet stream does not establish any desired ground speed. The relevant quantities are wind direction and strength along the actual route, at the aircraft’s altitude and time of passage. Crosswinds, changing headings and sections outside the strongest winds all affect the result.
To reconcile a 25,680-kilometre journey with thirteen hours, a proposed explanation must sustain the necessary average across the whole trip. A brief peak on a flight tracker would not demonstrate that. The return journey also deserves examination, because winds that help one direction can hinder the other.
A practical way to investigate the claim
Readers can make this comparison more rigorous without accepting either side’s rhetoric. Choose a specific flight number and date. Record departure and arrival in a common time standard, distinguishing gate times from takeoff and landing. Local clock readings alone can be confusing across time zones and the International Date Line.
Next, preserve the available track and note gaps instead of treating interpolated lines as continuous observations. Identify the aircraft type, compare the proposed route lengths and examine upper-air weather for that date. Calculate the average ground speed required by each geometry before choosing an explanation.
Finally, repeat the process in both directions and with other southern routes. A model becomes stronger when the same rules explain several journeys without changing the map or inventing new conditions for each one.
What this route tells us
Dubay’s video raises a question worth answering carefully: what exactly do flight times establish? A comparison of layovers alone is insufficient. A comparison combining explicit distances, aircraft capabilities and winds is much stronger.
For Sydney–Santiago, the available evidence is consistent with a spherical Earth and contradicts the familiar north-polar map when treated as a literal, uniformly scaled plane. That conclusion follows from testable differences, not from dismissing people who ask questions. Curiosity is most productive when every proposed world is required to make predictions that real journeys can check.
