Auckland, New Zealand and Madrid, Spain are a near antipodal pair. Both are located at the diametrically opposite points to each other on Earth’s surface. Therefore, we can fly from Auckland in any direction and arrive in Madrid after traveling a roughly similar distance, regardless of the direction taken.
Any flight between an antipodal pair has a similar duration even though the different flights have different directions. This fact is only consistent with spherical Earth and cannot possibly be explained if Earth is flat.
As an example, on a flat Earth, the flight trip Auckland–Tokyo–Madrid is almost a straight route between the two locations. Meanwhile, Auckland–Santiago–Madrid involves a massive detour, and it should take much longer than the aforementioned straight route. However, contrary to what is expected in the flat Earth model, both routes have a similar flight duration.
These flight durations were from Google Flights in October 2019.
- Auckland–Santiago–Madrid: 11h 0m + 12h 40m = 23.67 hours
- Auckland–Buenos Aires–Madrid: 11h 45m + 11h 35m = 23.33 hours
- Auckland–Los Angeles–Madrid: 12h 15m + 11h 5m = 23.33 hours
- Auckland–Tokyo–Madrid: 11h 0m + 14h 10m = 25.17 hours
- Auckland–Shenzen–Madrid: 11h 45m + 14h 0m = 25.75 hours
- Auckland–Perth–Doha–Madrid: 7h 25m + 11h 50m + 7h 15m = 26.5 hours