My brother is a captain with Delta and flies to Amsterdam several times a month. On the map, the route from Detroit to Amsterdam is a straight line. So to me, logically he should be able to get in the airplane, take off, set his heading and just drink coffee until he gets there.
But when I shared my logic with him, he laughed at me (something he spends way too much time doing). When I asked him what was funny, he said: “Things simply don’t work that way. I spend most of my time making course corrections.”
He explained: “Things are never as they seem to be. Even getting the very best information ahead of time is not enough. Conditions change. Circumstances arise. If I set an initial heading but don’t pay close attention to what is happening, I will never reach my destination.”
There are many factors that can take a plane off course. Wind changes in direction and intensity. Storms pop up. Volcanoes spew ash (although not very often thankfully). Sometimes the course change is only a few degrees. But in the long haul, a few degrees can be huge. Simply put, the situations are rarely like you thought they would be when you take off.