## Reasons for Preferring Flight Routes With a Stop to the Non-Stop Routes

Many flight routes cannot possibly exist if Earth is flat. Flat-Earthers showed the availability of the same routes with a stop to “prove” the non-stop routes do not actually exist. In reality, there are reasons airlines provide these routes with a stop, and some passengers do prefer to fly these routes.

## Flight Instruments

Pilots can easily observe that Earth is a sphere, either by visual observation or from the aircraft’s flight instrument.

The level indicator is above the visible horizon. It is the dip of the horizon caused by the fact that Earth is a sphere. Earth’s horizon itself is visibly curving. The horizontal component of the velocity vector is often not the same as the plane’s direction due to the wind & the Coriolis effect from Earth’s rotation.

## Antipodal Flight Route: Jakarta–Bogota

Jakarta & Bogota are a near antipodal pair: the opposite points on Earth’s surface. We can fly from Jakarta in any direction and arrive at Bogota after traveling a similar distance, irrespective of the direction we leave Jakarta.

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.

For example, on a flat Earth, the flight route of Jakarta–Hong Kong–New York–Bogota is almost a straight route between the two locations. Meanwhile, the Jakarta–Sydney–Auckland–Santiago–Bogota route 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.

## Flight Durations

• Jakarta–Istanbul–Bogota: 12h 0m + 13h 45m = 25.75 hours
• Jakarta–Hong Kong–New York–Bogota: 5h 5m + 16h 0m + 5h 42m = 26.783 hours
• Jakarta–Tokyo–Houston–Bogota: 7h 35m + 12h 5m + 4h 55m = 24.583 hours
• Jakarta–Sydney–Auckland–Santiago–Bogota: 6h 55m + 3h 5m + 11h 0m + 6h 14m = 27.23 hours

## Perth–Johannesburg Flight Route

By comparing the duration of the non-stop Perth–Johannesburg flight route with the same route with a stop, we can conclude the route is only possible if Earth is a sphere.

There are other Perth–Johannesburg flights but with a stop, like in Dubai. Flat-Earthers use it to “prove” a flat Earth. In reality, it does not mean the non-stop route does not exist. And it is easy to verify the existence of the non-stop route. These are consistent only with a spherical Earth and can never be explained if the Earth is flat.

## Why It is Difficult for Satellites to Locate the Missing MH370 Flight

If many satellites provide navigation and surface imagery, why is it challenging to locate the missing MH370 flight?

Satellite navigation, including GPS, is passive. Satellites emit signals, which are processed by receivers —including those on board the MH370— to determine their own locations. The satellites never receive anything from MH370 and cannot determine its location.

Airliners do broadcast their positions using ADS-B. However, at the time of MH370, only ground-based ADS-B stations existed. There were no satellite-based ADS-B receivers yet, and no coverage in the middle of oceans.

## Non-Stop, Long-Haul Flight Routes in the Southern Hemisphere

There are many non-stop, long-haul flight routes between different continents in the southern hemisphere, without crossing the northern hemisphere. These routes are only possible if Earth is a sphere, and impossible if Earth is flat.

Flat-Earthers claim that all long-haul flights south of the Equator always do a stop north of the Equator. In reality, there are plenty of non-stop routes between these locations, showing that Earth is a sphere.

## Airplanes Going Over Earth’s Curvature

To an observer on the ground, an airplane at 36000 ft will start going over Earth’s curvature at a distance of 400 km. However, we are also limited by atmospheric visibility. In an extremely best-case scenario, we can only see up to 240 km.

We can easily see ships going over Earth’s curvature, and flat-Earthers like to demand us the same thing for airplanes. In reality, at the typical distance a plane does that, it is far out of visibility range. But if it is very low, like when approaching a runway to land, it is possible to see the plane going over the curvature of the Earth.

## Qantas QF14 Flight: Buenos Aires – Darwin

In early October 2021, Qantas flew a one-off repatriation flight from Buenos Aires, Argentina, to Darwin, Australia. It was the southernmost long-haul flight closer to the South Pole than any other passenger flight.

If Earth were flat, the flight should fly over South America, Canada, Russia, Japan, and Indonesia. But it flew over Antarctica instead, because the Earth is a sphere, not flat.

## ETOPS

ETOPS is a safety regulation that prohibits airliners from flying too far from the nearest diversion airport. A higher ETOPS rating allows the flight to fly farther from the closest airport but has more stringent requirements, demanding higher operational costs.

As of 2021, there is no flight route over Antarctica, and flat-Earthers use it to “prove” a flat Earth. In reality, a reason for that is the lack of diversion airports in Antarctica, requiring aircraft with a higher ETOPS rating. Due to costs & the lack of market, no airliner considers it commercially viable yet.

## Flying Over Antarctica: Airliner vs Private Flight

Commercial passenger airliners are similar to public transits. The operator determines the route, and passengers take them if they fulfill their needs. On the other hand, a private flight is similar to a taxi. The passenger determines the origin and destination of the flight.

There is currently no airliner providing a route over Antarctica, and flat-Earthers use it to “prove” that it is impossible to fly over Antarctica. In reality, the airliners simply decide not to provide such routes due to commercial or other reasons. Not because it is impossible to fly over Antarctica. We can take private flights if we really want to fly over to Antarctica, just like we take taxis to go to a location not serviced by public transit.

## Artificial Horizon and Earth’s Curvature

An artificial horizon, or attitude indicator, is a flight instrument that indicates the aircraft’s orientation relative to Earth’s horizon and gives an immediate indication of the smallest change of orientation. An artificial horizon utilizes a gyroscope to detect the change of orientation and pendulous vanes to continuously correct the orientation relative to the level.

Flat-Earthers claim that an artificial horizon should drift over time if the airplane is flying over the spherical Earth because the gyroscope will eventually drift and no longer points toward Earth’s center. In reality, an artificial horizon has a self-correcting mechanism, keeping the gyroscope upright if it is displaced for any reason, including by the aircraft’s motion following Earth’s curvature.

## Hovering Helicopter and Earth’s Rotation

Because of inertia, we cannot travel to another location by hovering inside a helicopter and waiting for the Earth to rotate below us until we are above our destination.

Flat-Earthers claim that we cannot do such a thing as ‘proof’ of a motionless Earth. In reality, when still on the ground, the helicopter is already moving at the same velocity as Earth’s surface.

## Curved Airplane Window and Observation of Earth’s Curvature

With careful planning, we can easily observe Earth’s curvature from an airliner. To “explain” the observation, flat-Earthers invented the excuse that it is caused by the distortion from the shape of the airplane’s window.

In reality, all camera lenses are curved, too, yet most of these lenses produce normal, rectilinear images. The fact that the shape of the window is curved does not mean looking through the window will produce a curved horizon.

## Frame of Reference

A frame of reference consists of an abstract coordinate system and physical reference points that uniquely fix the coordinate system and standardize measurements. Speed or velocity is relative to a specific frame of reference. It is possible that two speeds/velocities are measured relative to a different frame of reference and thus cannot be directly compared.

Flat-Earthers like to compare two different speed measurements like an airplane moving at 900 km/h (560 mph) and Earth’s surface near the equator at 1674 km/h (1040 mph). They would conclude the airplane should not be able to catch up with Earth’s surface and would not land if the Earth is rotating. In reality, both the speeds are measured relative to a different frame of reference, and therefore, cannot be compared directly.

Airline pilots are educated to understand that Earth is a sphere and depend on the knowledge to do their job. They have plenty of opportunities to observe Earth’s curvature, either visually or using the airplane’s instruments. They are also aware that there are people out there that somehow believe in flat Earth, and some of the pilots even actively debunk flat Earth in their spare time.

Flat-Earthers asked some of the pilots if Earth is flat and rudely recorded the conversation. Then, they would brag online if they can get the pilots to “admit” in camera that Earth is flat. In reality, these pilots are professionals on the job and aware of the erratic behavior of the flat-Earthers. They were just trying to get rid of these people as quickly as possible without making a scene.

## Sydney-Santiago Flight Route

The Sydney-Santiago flight route is one of the southernmost passenger flights. Such a route is impossible if Earth were flat and confirms that Earth is a sphere. It is easy to verify the existence of this route from flight websites.

On a flat Earth, this route should go across the United States. But the duration of the Sydney-Santiago route with a stop in the US is much longer than the non-stop route because Earth is a sphere, and this route does not go anywhere near the United States.

## Wind & Jet Stream Excuses

Flight durations are a useful proxy for the distances between cities and easily debunk flat Earth. Flat-Earthers invented the “explanations” that the discrepancies of the flight durations in the flat Earth model are caused by winds and jet streams.

In reality, the required wind speed in such a scenario far exceeds the typical jet stream speed. Furthermore, the wind does not affect similar routes the same way in the flat Earth model. And we can easily account for the wind speed differences by averaging the flight durations in both directions. Continue reading “Wind & Jet Stream Excuses”

## Singapore–New York and Melbourne–Santiago Flight Routes

As of 2020, the Singapore–New York flight route is the world’s longest flight route, while the Melbourne–Santiago route is the most southernmost route. The real-world durations of these routes are only consistent if Earth is a sphere.

On the flat-Earth model, the Melbourne–Santiago flight route should be a longer flight than the Singapore–New York route. These routes’ real-world durations disprove the flat-Earth model.

## Airplanes Do Correct for the Coriolis Effect

Airplanes do correct for the Coriolis effect. They constantly make adjustments to counter forces that try to push them away from the planned route, including the Coriolis force.

Flat-Earthers claim the Coriolis effect does not appear to affect airplanes, and they use it to “prove” that Earth is stationary. In reality, the Coriolis effect does affect airplanes, and we do have to correct for it. But the effect is tiny, and we can safely ignore it in flight planning.