Is it really faster to fly east than west: Scientists have an answer
Many people might think that the Earth's eastward rotation is the reason for faster eastward travel; it is not. As NASA's Robert Frost explained, the Earth's rotation has no direct relationship to flight speed. Just as you don't walk faster when you go from east to west, the direction has no effect on the speed of an airplane.
The Earth's rotation on its own axis may seem like an intuitive answer. And while it doesn't directly affect the airplane, the truth is to be found in its indirect effect on the weather. More precisely, the real answer relates to a geophysical phenomenon known as jet streams, Simply Flying writes.
Jet streams are formed by the heating of the atmosphere and the action of the Earth's Coriolis force. They can reach speeds of 80 to 140 miles per hour and significantly affect flight times.
While jet streams can reduce flight time and fuel burn, they also increase the risk of clean air turbulence. Studies show that due to global warming, clean air turbulence will increase, making flying through jet streams riskier in the future.