Why does the plane fly faster in one direction, and slower in the other?

Direction of the wind

Swimming against the current is more difficult than following it. Walking with the wind blowing right in your face is also not easy. So it is with airplanes: a tailwind drives up, a headwind slows down.

The ground speed of an aircraft depends on the direction of the wind. Most often it blows from west to east, so such flights with a tailwind are shorter than from east to west against the direction of the wind. This is the conclusion reached by scientists from the Woodshole Institute of Oceanography and the University of Wisconsin in Madison. Their research is published in the journal Nature Climate Change.

The main factor influencing the duration of the flight is the circulation of the upper atmosphere.

Kris Karnauskas Study Author, Associate Professor, Department of Geology and Geophysics, Woodshoal Institute of Oceanography

But there are also nuances here. You have to fly with a favorable breeze, and there is nothing to worry about. But for safety reasons, takeoff and landing should be carried out strictly against the wind. A crosswind is also allowed, but not a tailwind, because it increases the distances necessary for takeoff and deceleration. Simply put, in a head-on wind, the plane will take off more easily and will not roll out of the runway.

Air corridors and waiting times

The air corridor is a kind of route in the air along which the aircraft route runs. But the round trip is not the same, so the time is different.

Also, the journey back takes longer, because the plane takes off quickly, but when landing, it is most often delayed in the so-called queue from other aircraft. If there are many planes in the airport area, then everyone will not be able to land at once. We have to wait: go around or, at the request of the dispatcher, reduce the speed before approaching. These factors delay the plane on the way.

Earth rotation and Coriolis force

The Earth is a non-inertial (rotating) frame of reference. There are special forces at work in this system. One of them is the Coriolis force.

This force affects all bodies moving at non-zero speed. It deflects the air flow to the side: in the Northern Hemisphere to the east, in the Southern Hemisphere to the west. And due to the non-inertial force, the weight of the plane changes depending on the direction of the route. When traveling from west to east, the aircraft becomes lighter and spends less thrust to create lift than an aircraft flying in the opposite direction. And the less the weight of the plane, the higher the speed it can develop and the faster it can cover the distance.