I'm copying this but the numbers are way off
:
A flight from New York to London takes on average between 7 to 7.5 hours. Conversely, it takes about 8 to 8.5 hours for a flight to cross from London to New York. The difference here, as any Round Earther will tell you, is tailwinds, another strong factor in the alleged discrepancy in southern flight times. More on that later though, first let me walk you though a thought experiment.
Imagine the Round Earther's concept of the earth; a sphere suspended in space. Imagine you're looking at it miles and miles above the surface so you can see it in its entirety (or as much as the round-earth model allows). Look down from the North Pole. A Round Earther will tell you that it is rotating counter-clockwise. Now, look closer. Take note of planes making the trip from New York to London and back. For a moment, recall your lessons of Newtonian Physics; the first law to be precise. Objects at rest tend to stay at rest and objects in motion tend to stay in motion unless acted upon by an outside force. A brief spark of doubt clouds your thoughts and a question arises. If the planes are no longer in contact with the earth and being slowed by wind resistance, how is it that the ones going from London to New York aren't concluding the flight much quicker than the ones going from New York to London. After all, they are no longer in contact with the earth and it should be spinning independently underneath them as they make their transatlantic flight, thus shortening it considerably.
To rephrase, it would stand to reason that a flight flying from London to New York would be shorter than one flying from New York to London because the earth would spin New York closer to you as you flew. In other words, the spinning of the earth would move New York directly towards you, just as it would spin London away from you if you were crossing from New York to London.
In reality though, the opposite is true. Due to tail/headwinds, flights from New York to London are shorter than the opposite. Tailwinds and headwinds account for much of the variance in flight times in the southern "hemisphere" and can be seen on a smaller scale here.
To conclude, let me reiterate. If the earth did spin as in the round-earth model, then flight times would be shorter when flying from London to New York. As that is not the case (an in fact the opposite is true due to high altitude winds) the world is clearly not round and provably flat
. I can't think of any other topic that inspires such anger. 
