Extremely strong winds high over the Atlantic Ocean pushed commercial flights to near record speeds this weekend, with some passenger planes recording ground speeds of more than 800 miles per hour. Eastbound planes, including a Virgin Atlantic flight from Washington DC to London, landed significantly earlier than expected due to the bizarre weather.
According to tracking site FlightAware, the Virgin Atlantic service, on a Boeing 787 Dreamliner, reached a top ground speed of 800 miles per hour at an altitude of 33,000 feet – about 200 miles per hour faster than average. Instead of the usual seven hours, the journey took just six hours and twenty minutes, allowing passengers to disembark 45 minutes earlier than expected.
Has Virgin broken the sound barrier?
No. The top speed of the flight was faster than the speed of sound, which at static conditions at sea level is 1,220 km/h. However, the speed of sound varies depending on the temperature and the medium through which a sound wave propagates.
Because the plane was flying with a wind speed of 200 miles per hour, the airspeed was actually closer to 600 miles per hour, not 800 miles per hour—lower than the speed of sound relative to the environment it was in.
When an airplane flies above 25,000 feet, its speed is referred to as a Mach number: a percentage of the speed of sound. A plane breaks the sound barrier at Mach 1, creating pressure waves that follow the plane. A sonic boom is heard as those waves pass by an observer.
Pilots are generally not concerned with reaching the speed of sound – which can be dangerous in some cases. Nick Eades, one of the longest-serving Boeing 747 pilots, notes that commercial airplanes are generally not designed to fly that fast.
“In the early days of jet aircraft, there was a phenomenon known as the Mach Tuck,” he says. “If the plane reached the speed of sound, the force would cause the nose to drop, which is a very dangerous situation.
“It’s now designed based on the modern jet aircraft, but you still don’t want to get anywhere near the speed of sound because that’s not what those planes are supposed to do.”
The Virgin flight was not the fastest ever transatlantic civilian crossing – that record is held by BA and Concorde, which flew from New York to London in two hours, 52 minutes and 59 seconds in 1996 – with a top speed of 2,150 km/h . In 2020, another BA flight reached speeds of 800 mph (1,325 km/h) – the fastest ever for a subsonic flight – aided in part by a powerful jet stream. The flight lasted just four hours and 56 minutes.
The power of the jet stream
While the Virgin flight did not break this record, it did highlight the power of the jet stream, which pilots use to reduce flight time and fuel consumption. This band of fast-moving winds is located between eight and ten kilometers high in the atmosphere and is created by the spread of heat from the equator to the poles. About 10 miles (16 kilometers) wide and 2,000 feet (600 meters) deep, westerly winds in the Northern Hemisphere become stronger as altitude increases.
Manoj Joshi, professor of climate dynamics at the University of East Anglia, explains: ‘The jet stream is usually strongest in winter due to the temperature difference between the equator and the North Pole. There is very little variation between time of day, but the jet stream does shift as atmospheric waves and weather systems move past it.
Due to climate change, the jet stream is expected to become stronger in the coming years. Close to the Earth’s surface, the polar regions warm more than the subtropics, causing winds to weaken at lower levels. At higher altitudes, however, the reverse is true: the subtropics warm and the polar regions are cooler, a quirk of Earth’s rotation.
For passengers, this means travel times in the Northern Hemisphere are faster if they travel east. “I flew from Boston to London in less than five hours because we were being pushed by the huge tailwind,” says Eades. “But if I were to fly from London to Boston, it would take me almost eight hours because I’m flying in that jet stream.”
Pilots use Met Office data to calculate the impact the jet stream can have on a journey, plus the potential reduction in fuel consumption. A 2021 report from the University of Reading found that flights between London and New York could use 16 percent less fuel by closely monitoring the jet stream tailwind. The report also notes that this practice, when carried out accurately, is significantly more cost-efficient than other emissions reduction measures.
Jetstream safety
A passenger is unlikely to notice the speed difference until landing early. What they may encounter, however, is turbulence when an aircraft reaches the edge of the weather pattern.
According to Eades, that is where the danger lies. “As a pilot you have to be very careful entering and exiting the jet stream,” he says. “It can be a huge difference in temperature and speed.”
That shock is known as clear air turbulence, which can cause serious cabin disruption and is much harder to predict than turbulence caused by storm systems or cloud cover. “It’s critical to put up the seat belt signs and strap people in because sometimes you know you’re in an area of obvious turbulence, but not in the exact location,” Eades said.
Regardless of the turbulence risk, the jet stream is still an essential tool in flight path management. Will airlines use it even more as speeds increase? The answer is complicated. Cathie Wells, a research fellow at The Walker Institute, notes that new route structures, introduced in 2022, will allow airlines to use the jet stream more easily than in the past. This means that time minimization will be a priority for the time being.
“Air velocity is also an important part of reducing fuel consumption and emissions,” she says. As fuel costs – and expectations to reduce carbon emissions – rise, aircraft may reduce their speed while flying on jet stream-optimized routes. That means transatlantic passengers can’t always expect to get home as early as those on the Virgin flight.