We can use the duration of a flight route to roughly determine the distance between two locations. Then, we can use this to determine which model better represents reality: the flat-Earth model or the spherical Earth model.
In the flat-Earth Model, the distances between two locations become more unreasonable as we go further south. To illustrate this fact, we can use the flight route of Sydney-Santiago to help us with the calculations. This flight route is one of the most southernly flight routes.
According to the so-called flat-Earth map, the flight route of Sydney-Santiago should traverse the United States. We can now try comparing the duration of a non-stop flight of Sydney-Santiago to the same flight, but with a stop in the United States.
- Sydney-Santiago: 12h 40m. Santiago-Sydney: 14h 5m. Average: 13h 22m
- Sydney-Los Angeles: 13h 50m. Los Angeles-Sydney: 15h 0m. Average: 14j 25m
- Los Angeles-Santiago: 10h 45m. Santiago-Los Angeles: 11h 25m. Average: 11j 5m
(data obtained from Google Flights)
The duration of the non-stop flight of Sydney-Santiago is 13 hours 22 minutes. But the same flight with a stop in Los Angeles is 25 hours 30 minutes, or almost twice the duration.
If the flat-Earth model is correct, then both flights should have a similar duration, and it certainly would not be twice longer just because you make a stop in a city very close to the flight route.
The real reason is that the flight does not actually go over the United States. This happens because the Earth is spherical, and the flight traverses the southern Pacific Ocean, which is the great circle route between Sydney and Santiago.
If a passenger decides to take the same flight with a stop in Los Angeles, then he would make a massive detour, and the trip would become almost twice longer than the non-stop flight.
The corresponding flight numbers, and links to FlightAware.
- Sydney-Santiago: Qantas QF28, FlightAware
- Sydney-Los Angeles: Qantas QF11, FlightAware
- Los Angeles-Santiago: LAN Airlines LA603, FlightAware