You are importing your 'up/down' model from two-dimensional thinking. You aren't a two-dimensional being, you are 3 dimensional. Flat-earth comes from a 2 dimensional mindset and understanding. There is no slam here, it is just the difference for 'understanding' the contexts. In the 3 dimensional model, up/down are not 'flat.' Example: Attach the base of a globe to the wall. Get up and start walking while it spins. Up is over North America one step, but not the next. A bit of egocentricity is involved with a flat-earth model. A globe requires thinking outside of a 2 dimensional square (box). :e4e:
All that's required to see that the earth is flat is your eyes, the mind does the rest.
If a jet follows a "straight" path and reaches 2000 miles, on curvature map where L = 2000, the curvature of the earth would have "dropped", in relation to the starting point, 542 miles, as per curvature of earth diagram below.
View attachment 26170
The rate of drop, if flying a straight path, as you can see by the chart is exponential. A pilot flying a jet at 600 mph and at low altitude, if not adjusting for a curvature, would see the earth or ocean drop 66 feet in 1 minute, from his starting altitude. In 2 min the drop would be 266 feet, and in 3 min the drop would be 600 feet. No such drop is ever seen or been demonstrated.
--Dave