If you’ve taken many transcontinental flights, you may have felt that flying eastward seems to take less time than flying in the opposite direction. That’s not just a feeling, it’s a fact that flying eastwards objectively takes less time than flying westwards for the same distance.

Westward flights are slower than eastward flights due to eastward flights being able to take advantage of jet streams, which are a series of high altitude winds that planes can piggyback on to increase speed. 

The Main Reason Why Westward Flights Are Slower Than Eastward Fights (Jet Streams)

Jet streams are the main reason for faster eastward flights. Jet streams are simply a series of fast-flowing narrow air present in high altitudes.

The jet streams are caused by atmospheric heating from solar radiation and the earth’s Coriolis force. The Coriolis force is a rotating object with a perpendicular force to its rotation axis.

Places on the earth that are closer to the equator rotate much faster than places closer to the earth’s poles. Additionally, solar heating also affects the winds, causing them to flow from high pressure regions of low pressure.

These jet streams have a strong effect on planes. Planes that are traveling towards the east can pick up additional tailwind, speeding up their journey. In contrast, a westward flight would involve a plane that would be flying against this powerful wind. 

The most important jet streams are the Polar and Sub-tropical streams; they’re located at 60° and 30° north and south of the equator, respectively. The Polar stream is the stronger of the two, and it causes much faster winds than the Sub-tropical stream. Most planes flying transatlantic or transpacific routes use the Polar stream.

Solar heating and the Coriolis force combine to produce jet streams that flow from west to east in an undulating pattern. The jet streams vary in strength and altitude, but they’re the strongest over the poles. 

Westward vs. Eastward Flights and the Rotation of the Earth

The Earth rotates from west to east. The speed of the Earth’s rotation at the equator is approximately 1,000 km/h. This speed would imply that westward flights should take more time, since both the earth and the plane would be moving in the same direction. 

In reality, the earth’s rotation has no effect on flight speed. An aircraft actually moves away from its destination as it continues to spin with the earth because the Earth’s atmosphere rotates in addition to its surface.

So despite popular belief, the rotation of the Earth actually has no bearing on why westward flights are slower than eastward flights.

First Commercial Aviation Use of the Jet Stream

Jet streams were used in commercial aviation for the first time in 1952 on a flight that took off from Tokyo, Japan and landed in Honolulu, Hawaii. The plane used jet streams to reduce its journey from 18 hours to only 11.5 while flying at a low altitude below 25,000 feet. 

Subsequent airlines quickly realized that jet streams could be extremely valuable for reducing flight times and costs, so they began using them for planning routes. 

As the Jet Stream’s direction is from west to east, they make it easier to fly with the stream than against it. For this reason, the flight time from the same two locations is lower when the journey is from east to west than vice versa. 

For example, if flying from New York to London takes six and a half hours, the flight from London back to New York would take seven and a half hours. The jet streams cut off an hour of flight time from going to London from New York. 

This principle applies even to shorter transcontinental flights between destinations. For example, the Jet Stream cuts down traveling time from Los Angeles to New York by an hour than if the destinations were reversed.

Flying Eastwards vs. Westwards – Flight Planning

Flight times, flight paths, and scheduling are all majorly impacted by the jet streams. For that reason, airlines check jet stream patterns regularly, and they alter their routes accordingly. In fact, because of the jet streams, it sometimes makes sense to take a physically longer route.

Another advantage of the jet streams is that it’s easy to re-route a westward flight if an airplane wants to avoid the effects of the jet stream. As such, flights are routed carefully to take full advantage of the jet streams. 

If Flying Around the World, Is It Better to Fly East or West?

If you want to fly around the world, it would be better to fly westwards for comfort and eastwards for economy and speed. There are advantages and disadvantages of flying either direction, so the right choice depends on what you want. 

By flying westwards, flight times are longer but more of your flight will be spent in daylight hours, so you can expect less jet lag and reduced discomfort overall.

By flying eastwards, you’ll have shorter flight times, but your flights will likely have less comfort and involve a lot more jet lag. Another benefit of flying eastwards is that ticket prices are generally cheaper when flying eastwards than westwards. 

Flying the same distance eastwards takes less time on average than flying westwards. This difference is because of the jet streams, a series of high altitude winds that provide planes with tailwind, reducing travel time. Although these winds speed up travel, they can lead to a decrease in travel comfort.

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