It could work either way, but mostly it makes a rather tiny difference. Imagine swimming laps in a mobile pool on the back of a big HGV going down the Interstate; Would you swim laps faster going towards the engine or the tailgate? Well, neither. The density of the water is more important than the motion of the vehicle.
You'd have to fly in a vacuum to get a difference -- like as a satellite far above the Earth's atmosphere.
Prevailing wind speed is a much bigger influence on air flight.
For instance, I regularly fly from Britain to the west coast of North America. Going west (against the way the Earth turns), seems like it ought to be faster. The Earth is rotating at a speed of roughly 1040 miles per hour (about 1700 km / hour). But the resistance of the atmosphere and the weight of the loaded aircraft itself, work out as tremendous barriers to movement. Less so the higher up the plane flies, but still like being in that swimming pool. Anyway, it takes about 12.5 hours to get from London to LA.
Coming back to London can take as little as 10.5 hours. Even though the Earth is theoretically moving away from the plane at 1040 miles/hour. But the thick atmosphere moves with the Earth, so the planet is moving with the plane, after all.
Why faster going West to East? The prevailing winds blows from West to East and pushes the aircraft along, giving a boost of up to 30mph.
You'd have to fly in a vacuum to get a difference -- like as a satellite far above the Earth's atmosphere.
Prevailing wind speed is a much bigger influence on air flight.
For instance, I regularly fly from Britain to the west coast of North America. Going west (against the way the Earth turns), seems like it ought to be faster. The Earth is rotating at a speed of roughly 1040 miles per hour (about 1700 km / hour). But the resistance of the atmosphere and the weight of the loaded aircraft itself, work out as tremendous barriers to movement. Less so the higher up the plane flies, but still like being in that swimming pool. Anyway, it takes about 12.5 hours to get from London to LA.
Coming back to London can take as little as 10.5 hours. Even though the Earth is theoretically moving away from the plane at 1040 miles/hour. But the thick atmosphere moves with the Earth, so the planet is moving with the plane, after all.
Why faster going West to East? The prevailing winds blows from West to East and pushes the aircraft along, giving a boost of up to 30mph.