Passengers aboard British Airways Flight 112 from New York’s Kennedy International Airport to Heathrow Airport outside London got some good news Thursday morning. The flight, which normally took about six hours, was scheduled to arrive 50 minutes early.
Other flights traveling east over the Atlantic Ocean this week are arriving early, in some cases up to an hour early, because of the jet stream that is blowing in their favor.
For example, a United flight that departed Newark Liberty International Airport on Tuesday night arrived at Charles de Gaulle Airport near Paris 58 minutes early, a flight that typically takes about seven hours, according to flight AwareA site that tracks aviation traffic.
Tuesday’s Emirates flight from Dallas Fort Worth International Airport in the United Arab Emirates to Dubai was expected to take 13 hours 44 minutes. According to FlightAware, it landed 57 minutes early.
Here’s what you need to know about these early arrivals.
What is jet stream?
According to the National Oceanic and Atmospheric Administration, the jet stream is a band of strong winds moving from west to east in the upper levels of the atmosphere, or about 30,000 feet above the ground.
According to Jennifer Strozas, a meteorologist with the Aviation Weather Center at the National Weather Service, one way to understand how the jet stream can affect flights is to think about a boat on water.
“The atmosphere behaves like a fluid,” he said. “If the water is calm, the boat will also be steady. If there is a strong current in the water, it will naturally push the boat.”
When planes fly within the jet stream, strong winds can propel the plane faster, Ms. Strozas said.
According to Richard Levy, an aviation consultant who flies commercial aircraft, commercial flights typically fly at a speed equivalent to ground speed of about 570 mph.
The jet stream over the Atlantic is helping flights move faster than their average speeds this week. For example, a British Airways flight from New York to London reached a flight speed of 734 mph.
Jet-stream-assisted flights are not rare.
Kevin Kuhlmann, a professor of aviation and aerospace sciences at Metropolitan State University of Denver, said it is common for the jet stream to accelerate flights moving from west to east.
In summer, when flights are farther north it is common to be affected by the jet stream. In the winter, the jet stream may shift southward, Mr. Kuhlman said.
“That change could create a situation where it would increase traffic,” he said.
Jet-stream-assisted flights are not limited to transatlantic flights. Mr. Levy said he was used to the jet stream speeding things up when he was flying east over the Pacific Ocean.
Jet streams can also increase the speed of domestic flights. A jet stream flowing over the United States helped eastbound flights in February 2019 arrive much earlier than scheduled,
Turbulence may be an issue.
Experts say airflow is not always a boon for pilots and passengers. Flying through the jet stream can cause turbulence problems in some cases.
To avoid turbulence problems, Mr. Levy said, pilots will sometimes travel at lower speeds. He said flying through the jet stream could be like driving on a bumpy road.
The faster a person drives on a rough road, “the worse it is for the car and you,” Mr. Levy said, adding that it is better to drive slowly in those conditions.
“That’s what we do with unrest,” he said. “We bring it back.”
Mr. Kuhlman said pilots often encounter turbulence as they travel in and out of the jet stream.
“There will certainly be potential for unrest in that transition zone,” Mr. Kuhlmann said. “But just being in it doesn’t mean it’s dangerous.”
Still, turbulence could be a problem if there is no flight, jet stream or no jet stream, Mr. Levy said. Pilots remind passengers to keep their seat belts on to stay safe, and they stay in touch with air traffic controllers who can alert them to the possibility of turbulence.
Flying back may not be as fast.
Aircraft traveling from west to east may be aided by strong easterly winds, but the same current may have the opposite effect on aircraft traveling west.
“The opposite is also true,” Ms. Strozas said. “If it blows into a strong wind, this will effectively slow it down, like trying to paddle upstream.”
It’s possible to avoid flying westward in the jet stream, Mr. Levy said, because, “A, it slows you down; B, you’re going to burn gas like crazy without seeing anything; And C, turbulence,” he said, adding that sometimes it cannot be avoided given the flight route.
On a westbound flight from London to New York City, Mr. Levy said, the jet stream can be largely avoided by flying north over Greenland.
“We don’t even go near it,” he said.
Early arrival is not always best.
Arriving at a destination ahead of schedule is usually good news.
“I would love to go to O’Hare in Chicago sooner,” Mr. Kuhlman said.
He added: “But then guess what? If you land the plane too early there is no gate for you.
Potential problem: Passengers may find themselves sitting on a plane, stuck on the ground while the crew waits for a gate to open so everyone can deplane.
Mr. Levy said the wait for the gate is less of a hassle for travelers at some airports in Europe, where there are dedicated gates for certain carriers. Flight-tracking computers also help avoid delays on the ground.
“As soon as the wheels come off the ground, the computer immediately knows what your flight time is,” he said.