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

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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.

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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.

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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.

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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.

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Asking Pilots

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.

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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.

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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

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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.

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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.

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Sydney-Johannesburg Flight Route

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The existence of the non-stop Sydney-Johannesburg flight route is only possible if Earth is a sphere. We can find that out by comparing its duration to the same route but with a stop.

There are other Sydney-Johannesburg flight routes, but with a stop, like in Dubai. Flat-Earthers use the existence of these routes to “prove” a flat Earth. In reality, it does not mean the non-stop route does not exist & it is not difficult to verify that the non-stop route exists.

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Polar Circumnavigation

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Polar circumnavigation is complete navigation around Earth through both the North Pole and the South Pole. Several parties have successfully done it, and it is only possible if Earth is a sphere.

Flat-Earthers incorrectly claim that Earth circumnavigation has never been done through both the poles, and they use it to “prove” a flat Earth. In reality, many have successfully done such feats.

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Flight Routes During the COVID-19 Pandemic

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During the COVID-19 pandemic, many flight routes are being canceled, suspended, or cut down due to lockdowns, travel warnings, travel bans, or insufficient demand. These include flight routes that are impossible if Earth were flat.

Flat-Earthers looked for these routes, and when they could not find them, they use the lack of these routes to “prove” Earth is flat. In reality, they made these lookups during the COVID-19 pandemic, when most of these routes are not available or severely cut down.

Airplanes and Earth’s Rotation

An airplane exists on Earth. It has the same motion as the surface of the Earth, including Earth’s rotating motion. The motion and speed of an airplane are measured relative to Earth’s surface.

Flat-Earthers claim that an airplane should not be able to fly eastward or land. In reality, an airplane is moving relative to the surface. It has Earth’s motion as a component of its motion and does not need to chase Earth’s rotation.

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Pilots Are Taught to Work With the Fact Earth is a Sphere

Pilots are taught to work with the fact that Earth is a sphere. It is part of the education to become a pilot. Their job depends on the knowledge that Earth is a sphere.

Flat-Earthers wrongly claim that pilots are taught to fly based on a flat Earth. We can easily disprove these claims by reading some of the books these pilots use in their education.

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Flight Dynamics: the Assumption of Flat & Non-Rotating Earth for Simplification

In making mathematical models, physicists often remove real-world details that have little influence over the final results for simplifications. In flight-dynamics, it is often perfectly adequate to assume Earth is flat & non-rotating, even if the final aircraft will be flying over spherical & rotating Earth.

Flat-Earthers claimed to have exposed ‘a secret document’ from NASA, saying that Earth is flat & non-rotating. In reality, the document is simply a derivation of a flight dynamics problem, assuming flat and non-rotating Earth, which is a common assumption made to simplify flight models. It does not imply the Earth is flat and non-rotating.

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Eötvös Effect: Direct Evidence Earth is a Rotating Sphere

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Eötvös effect is the change in perceived gravitational acceleration when moving eastward vs. westward. An object will weigh slightly more when moving westward than when it is stationary or moving eastward.

The slight difference in weight due to the Eötvös effect can be measured in an experiment on a flight. The Eötvös effect is direct evidence that the Earth is a rotating sphere.

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Airspeed of Long-Haul Commercial Passenger Flights

The durations of commercial passenger flights are useful proxy data for the distance between cities. They easily debunk flat-Earth. Flat-Earthers invented “explanations” that different airplanes have different airspeeds to dismiss the data. In reality, all current long-haul airliners have a similar cruising speed.

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Airplanes Will Never Fly Into Space

An airplane relies on the lift from its wings, which depends on the airplane’s speed and the air density. As a result, a cruising airplane will fly at a constant altitude, following the curvature of the Earth.

Flat-Earthers claim if Earth is a sphere, an airplane has to dip its nose down periodically, or it would fly into space. In reality, an aircraft will follow Earth’s curvature and is unable to fly to space even if the pilot deliberately attempts to do that

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Spirit Level on an Airplane

During cruising, an airplane is practically level. It is flying perpendicular to the direction of gravity. The aircraft is still flying following Earth’s curvature and continuously changes its orientation. However, not only its orientation changing but also the direction of gravity, having the same amount of change. As a result, a spirit level on a flight will not show us the difference in orientation of the airplane due to its motion following the curvature of the Earth.

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