Flights traveling west to east are shorter because of jet streams, powerful rivers of wind in the upper atmosphere that blow predominantly from west to east. A plane flying eastbound gets a significant tailwind that pushes it along, while a westbound plane fights a headwind that slows it down. On a typical transatlantic route like New York to London, this difference adds up to roughly an hour of flight time each way.
The Jet Stream Explained
Jet streams are narrow bands of fast-moving air that sit at around 30,000 feet, right where commercial aircraft cruise. They flow in a wavy, generally west-to-east pattern across the mid-latitudes. According to NOAA, jet streams can reach speeds of more than 275 mph, though on most days they’re considerably milder. Two main jet streams affect flights in each hemisphere: the polar jet, which sits between roughly 50° and 60° latitude, and the subtropical jet, which runs near 30° latitude.
When your eastbound plane enters a jet stream, it’s like stepping onto a moving walkway at the airport. The aircraft’s engines are still doing the same work, but the air mass itself is carrying the plane forward. A plane cruising at 550 mph through a 100 mph tailwind is effectively covering ground at 650 mph. Flip the direction and that same 100 mph wind becomes a headwind, dropping ground speed to 450 mph. Over a five- or six-hour flight, that gap adds up fast.
Why Wind Blows West to East
The jet streams exist because of the way Earth’s atmosphere circulates. The sun heats the equator more than the poles, creating large-scale circulation cells that move air between different latitudes. In the mid-latitudes (roughly 30° to 60°, where most long-haul routes fly), a circulation pattern called the Ferrel cell moves air poleward and eastward near the surface. Earth’s rotation deflects this moving air to the right in the Northern Hemisphere, a phenomenon known as the Coriolis effect. The result is the prevailing westerlies: winds that blow from west to east across the mid-latitudes at the surface and, with far greater intensity, at cruising altitude.
Earth also spins faster at the equator than at the poles simply because the equator is a wider circle. Air masses moving from the tropics toward the poles carry that extra rotational momentum with them, which helps generate and sustain the jet streams’ west-to-east flow.
It’s Not Because the Earth Spins Under the Plane
This is a common misconception worth clearing up. Some people assume that a plane hovering in the air would let Earth rotate beneath it, making westbound flights shorter. That’s not how it works. The Smithsonian National Air and Space Museum compares it to jumping on a train: when you jump, you don’t fly backward because you’re already moving at the train’s speed. The same principle applies to aircraft. A plane sitting on the runway in New York is already moving eastward at roughly 800 mph along with the atmosphere and the ground beneath it. When it takes off, it keeps that momentum. Earth’s rotation doesn’t directly speed up or slow down your flight.
What Earth’s rotation does do is create the atmospheric circulation patterns that produce jet streams. So the planet’s spin matters, just not in the intuitive way most people imagine.
How Airlines Use This to Their Advantage
Airlines don’t just passively benefit from the jet stream. They actively plan routes around it. Over the North Atlantic, one of the busiest corridors in the world, air traffic controllers at Shanwick Center in Ireland and Gander Center in Canada publish a new set of organized flight tracks twice a day. These North Atlantic Tracks shift north or south depending on where the jet stream is flowing on any given day.
Eastbound tracks are designed to ride the jet stream for maximum tailwind. Westbound tracks are routed to avoid the strongest headwinds, sometimes taking a more southerly or northerly path that looks longer on a map but saves fuel and time by skirting the worst of the opposing wind. This means your eastbound and westbound flights between the same two cities may follow completely different paths across the ocean.
How Big Is the Time Difference?
On the New York to London route, eastbound flights typically take around 6.5 to 7 hours, while westbound flights run closer to 7.5 to 8 hours. That’s roughly an hour of difference, though it varies with the season and the jet stream’s strength on any particular day. The jet stream is strongest in winter, when the temperature contrast between the poles and the tropics is greatest, so the time gap between eastbound and westbound flights tends to be larger in January than in July.
Transcontinental U.S. flights show the same pattern. Flying from Los Angeles to New York typically takes about an hour less than flying back. Trans-Pacific routes see it too, though the routing over the Pacific is more complex because the jet stream’s position varies more widely.
In extreme cases, the jet stream can supercharge a flight. In February 2019, a Virgin Atlantic flight from Los Angeles to London hit a ground speed of 801 mph, well above the speed of sound, thanks to an unusually powerful jet stream. The plane itself was still flying at normal subsonic speed through the air. It was the air itself that was racing east.
The Jet Lag Tradeoff
There’s an irony to faster eastbound flights: despite the shorter travel time, flying east tends to cause worse jet lag. Your body’s internal clock runs on a cycle that’s slightly longer than 24 hours, roughly 24.2 hours on average. This means your body naturally drifts a little later each day and finds it easier to extend the day (as you do when flying west) than to shorten it (as you must when flying east).
After a flight from Los Angeles to London, for instance, your body clock is still on Pacific time. When it’s 7:00 a.m. in London and time to start your day, your internal clock thinks it’s 11:00 p.m. and wants to sleep. You’ll feel drowsy in the late morning, alert at odd hours, and struggle to fall asleep at a normal London bedtime. Adjusting requires your circadian rhythm to shift forward, which it does more slowly than shifting backward. So while the eastbound flight saves you an hour in the air, you may spend a couple of extra days recovering once you land.