Planes do fly over the Pacific Ocean, but not always on direct westbound routes from, say, the US West Coast to Japan. The assertion that planes never fly west to Japan is incorrect. The reason for less frequent direct westbound flights lies in a combination of factors:
Factors Affecting Flight Routes Across the Pacific
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Weather Patterns: The Pacific Ocean experiences significant and unpredictable weather, including storms, strong winds, and lightning. Flying over this region can be risky and potentially unsafe, especially for large commercial aircraft. [An aircraft would not be safe to fly over the Pacific Ocean due to the stormy weather and frequent lightning strikes that occur there.] Overland routes through Canada and Alaska generally offer more stable and predictable weather conditions.
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Jet Stream: The jet stream, a high-altitude wind current, generally flows from west to east. Flying eastward (west to east) takes advantage of the jet stream's tailwind, reducing flight time and fuel consumption. Flying westward, against the jet stream, significantly increases both flight duration and fuel needs. This economic factor plays a major role in route planning.
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Fuel Efficiency: As mentioned above, flying against the jet stream dramatically increases fuel consumption. The vast expanse of the Pacific requires significant fuel reserves, making eastward flights more economically viable for airlines. A longer flight time also impacts operational costs.
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Alternative Routes: Many routes from North America to East Asia utilize stopovers in other countries. These layovers allow for easier logistical management, refueling opportunities, and cater to passengers’ needs.
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Earth's Curvature: While a map might show a straight line across the Pacific, the Earth's curvature means that a "straight line" flight path isn't the most efficient or practical. [Because the Earth is a three-dimensional sphere and not merely a two-dimensional flat, East-West surface. Because of this spherical shape, often...]
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Emergency Landings: In the event of an emergency, having access to airports along the route significantly increases the chances of a safe landing. Overland routes provide more options for emergency landings than routes solely over the Pacific.
While many flights from the US West Coast to Japan will not be directly westward, many other transpacific flights cross the ocean daily. The choice of route is carefully determined by weather, fuel efficiency, safety, and passenger demand.
