It’s measured as flat countless times every day.
Now try again honestly, including the level of uncertainty.
A level flight of planes flying over thousands of miles above Earth at one altitude
Demonstrates they are flying level and nothing about the shape of Earth.
We have been over this countless time.
Your argument is entirely circular, basically saying Earth is flat so level is flat, so planes flying level is flying flat so Earth is flat.
Take out that assumption and it all falls apart.
To fly over a curved Earth, we would have to measure for the curvature.
No, they need to measure altitude and maintain it.
Planes would have to follow the curved surface below it
Which would be trivial, by maintaining their altitude.
Level measures for
perpendicular to down.
For plane, it is really just measuring air pressure and ensuring that doesn't change.
You cannot say there’s an unmeasurable and unseen curve
And we don't.
It has been measured countless times, and it has been seen countless times.
The horizon is the curve.
Seeing objects go over it is seeing the curve.
And measuring the angle of dip to the horizon, including how it changes with altitude is measuring the curve.
We’d have to know Earths exact rate of curvature before all flights at various speeds.
No, we wouldn't, as they would fly level.
How would the pilot know the difference between the distribution of mass being slightly off so the plane is pitching up because it is not trimmed for that exact distribution over a hypothetical flat Earth, vs they were flying straight but Earth curved below.
Both result in the same effect, the attitude of the plane relative to Earth pitches up resulting in them gaining altitude.
We have measurements for every surface, every curve and every flat surface, over any distances.
Including Earth.
So your best "evidence" is already refuted BS?
Why not just be honest and admit you have no evidence?