A transatlantic flight is the flight of an aircraft across the Atlantic Ocean, from Europe, Africa or the Middle East to North America, Central America, South America, or vice versa. Such flights have been made by fixed-wing aircraft, airships, balloons and other aircraft.
Early aircraft engines did not have the reliability needed for the crossing, nor the power to lift the required fuel. There are difficulties navigating over featureless expanses of water for thousands of miles, and the weather, especially in the North Atlantic Ocean, is unpredictable. Since the middle of the 20th century, however, transatlantic flight has been routine, for commercial, military, diplomatic, and other purposes. Experimental flights (in balloons, small aircraft, etc.) still present challenges for transatlantic fliers.
In 2016 Dr. Paul Williams of the University of Reading published a scientific study showing that transatlantic flight times are expected to change as the North Atlantic jet stream responds to global warming, with eastbound flights speeding up and westbound flights slowing down
The idea of transatlantic flight came about with the advent of the balloon. The balloons of the period were inflated with coal gas, a moderate lifting medium compared to hydrogen or helium, but with enough lift to use the winds that would later be known as the Jet Stream. In 1859, John Wise built an enormous aerostat named the Atlantic, intending to cross the Atlantic. The flight lasted less than a day, crash-landing in Henderson, New York. Thaddeus S. C. Lowe prepared a massive balloon of 725,000 cubic feet (20,500 m3) called the City of New York to take off from Philadelphia in 1860, but was interrupted by the onset of the American Civil War in 1861. (The first successful transatlantic flight in a balloon was the Double Eagle II from Presque Isle, Maine, to Miserey, near Paris in 1978.)
[taken from Wikipedia as a demo post]