A rip-roaring jet stream at more than 260 mph turbocharged the trans-Atlantic British Airways flight, which departed New York at 6:20 p.m. and landed in London at 4:43 a.m. Sunday, nearly two hours ahead of schedule.
The jet stream is the zone of strong winds about 30,000 feet high in the atmosphere, along which storms track. Many commercial aircraft hitch a ride along the jet stream to give themselves a speed boost. During the winter, the North Atlantic jet stream is at its most powerful, sling-shotting flights moving eastward across the Atlantic and slowing aircraft moving to the west, often adding more than an hour to the return trip and occasionally even a refueling stop.
As it shot across the Atlantic, the Boeing 747-400 jet reached a top ground speed of 825 mph. However, the jet did not actually break the sound barrier, because that is measured by its airspeed, or the speed of the plane relative to the air through which it is traveling. On the flight deck Saturday night, the pilots probably saw its airspeed hover close to its typical maximum cruising speed of Mach 0.855.
Other flights flying the same route on Saturday night also recorded flight times of just under 5 hours, including Virgin Atlantic flights 46 and 4. These flights were each operated by a newer, more efficient type of aircraft, the twin engine Airbus A350. Virgin Atlantic chose to highlight this distinction when taking a swipe at its transatlantic competitor, tweeting: “It’s true that we were narrowly beaten by a BA Boeing 747, however they had twice the amount of engines and burnt twice as much fuel as Captain Chris in our brand new, fuel efficient Airbus A350-1000.”
Supersonic commercial aircraft, specifically the British Airways Concorde, have crossed the Atlantic in much less time; its record still stands at 2 hours 53 minutes.
The howling jet stream that powered the flight across the Atlantic at such haste gained such strength as a result of the pressure difference between an unusually intense zone of low pressure east of Greenland and a high-pressure zone to the south. (High winds are the result of strong pressure differences.)
On Saturday night into Sunday morning, the deep low-pressure area near Greenland was rapidly intensifying, its pressure falling so fast that it met the criteria for a “bomb cyclone,” a description given to the strongest mid- and high-latitude storms. The storm’s pressure fell to the same level of some Category 5 hurricanes, dropping all the way down to 930 millibars.
“This is one of the deepest lows on record in the North Atlantic over the last decade!” the National Weather Service’s Ocean Prediction Center tweeted.
The resulting jet also steered a deadly storm, which spawned dozens of tornadoes in the eastern United States, across the Atlantic into Europe. As the storm, now dubbed Ciara, slammed into the United Kingdom, it unleashed wind gusts Sunday of 80 to 100 mph.
Storm Ciara also unloaded up to seven inches of rain in the United Kingdom, as the jet stream helped it to draw a tremendous stream of moisture, known as an atmospheric river, across multiple oceans, pulling water vapor from the tropical eastern Pacific and Caribbean.
Although the jet stream can help wintertime transatlantic flights have an especially speedy crossing, they are a leading cause of clear air turbulence. Flying through the core of a jet stream can often be smooth, but entering and exiting these zones of extreme winds can be rough, as considerable amounts of wind shear — or winds differing in speed and/or direction with height — is usually present.
Climate studies suggest that future transatlantic flights may actually be bumpier as the climate continues to warm. One study, published in the journal Nature last year, found that a statistically significant increase in vertical wind shear at jet-stream altitudes has already occurred across the North Atlantic.
This appears to be happening because of a sharpening contrast between the air high above the Arctic and the air found at similar altitudes above the equator. This development stands in contrast to what is happening at the surface, where the temperature difference is actually declining as the Arctic warms at more than twice the rate of the rest of the world.