The Impact of Jet Streams on Transatlantic Flight Times

The jet stream is a core of strong winds located approximately five to seven miles above the Earth’s surface, typically where commercial airliners cruise [2]. These winds blow from west to east due to the Earth’s rotation and the heating of the atmosphere by the sun.

In the North Atlantic, the jet stream forms at the boundary between cold polar air and warmer air from the south. The greater the temperature difference between these two air masses, the faster the winds blow. During winter months, when the temperature gradient is steepest, wind speeds within the jet stream can exceed 200 mph [3].

To understand how a plane can travel at 778 mph without breaking its engines, you must distinguish between airspeed and ground speed.

• Airspeed: The speed of the aircraft relative to the air around it.

• Ground Speed: The speed of the aircraft relative to a fixed point on the ground.

As explained by Flightradar24, flying in a jet stream is like walking on a moving walkway at the airport. If you walk at 3 mph on a walkway moving at 3 mph, your speed relative to the building is 6 mph, even though your legs are only doing the work for 3 mph.

When an American Airlines Boeing 777 reached 778 mph over the Atlantic in late 2023, it remained subsonic because its speed through the surrounding air was normal [2]. For more on how planes actually break the sound barrier, see our guide on Incredible Facts About Supersonic Flight.

Airlines and dispatchers don’t just fly in straight lines; they “surf” the atmosphere.

1. West-to-East (Tailwinds)

Flights heading from North America to Europe seek out the “core” of the jet stream to gain a massive boost. This often results in “early arrivals,” sometimes shaving 60 to 90 minutes off a scheduled six-hour flight. For example, a British Airways 747 once completed the New York to London route in just 4 hours and 56 minutes due to a powerful 200 mph tailwind [2].

2. East-to-West (Headwinds)

Coming back to the U.S. is the “uphill” battle. Pilots try to fly around or below the jet stream to avoid these 100+ mph headwinds. If they flew directly into the core, the plane would burn significantly more fuel and potentially run out of legal crew duty time. This explains why a flight from London to New York is consistently longer than the reverse leg.

While speed is a benefit, the jet stream brings two major challenges:

• Clear Air Turbulence (CAT): This occurs at the edges of the jet stream where fast-moving air meets slower air. This “wind shear” creates invisible ripples in the sky [3]. Unlike storm-related turbulence, CAT cannot be seen on radar, which is why pilots emphasize keeping seatbelts fastened even when the sky is clear.

• Fuel Consumption: While tailwinds save fuel, the erratic nature of the jet stream caused by climate change is making flight planning more difficult. Research indicates that climate change is increasing wind shear in the jet stream, leading to more frequent and severe turbulence for passengers [1].

If you find yourself on one of these longer, wind-battling westbound flights, you might want to prepare by checking out our list of the Best Books to Read on Long Flights.

• The Jet Stream is a Wind River: It flows west to east at altitudes of 30,000 to 40,000 feet, driven by temperature differences between air masses.

• Ground Speed vs. Airspeed: A plane can have a “supersonic” ground speed (e.g., 780 mph) while its airspeed remains subsonic, meaning it does not create a sonic boom.

• Winter is Faster: Jet streams are strongest in the winter when the temperature difference between the Arctic and the Equator is most extreme.

• Turbulence is Likely: The boundaries of the jet stream are prime locations for Clear Air Turbulence.

Action Plan for Travelers

1. Check the Duration: When booking, notice the time difference between your outbound and return flights; this helps you plan your sleep and arrival logistics.
2. Anticipate Early Arrivals: If flying to Europe overnight, you may arrive 30–60 minutes early. Ensure your hotel or transport is ready for an early landing.
3. Expect Bumps: When flying through the North Atlantic tracks, keep your seatbelt fastened whenever seated, as jet stream turbulence is often unforecasted.
4. Watch the Map: Use your in-flight entertainment system to track “Ground Speed.” If it exceeds 650 mph, you are likely riding the jet stream.

The jet stream remains one of the most powerful natural forces in aviation. While it can’t quite replace the efficiency of the future of supersonic travel, it remains the primary reason your flight across the “pond” varies so much in speed and comfort.