Riding a Wild Wind, Transatlantic Jets Fly Faster Than Ever, by Jack Stewart.
On Thursday, a Norwegian 787 [flying from Los Angeles to Paris] briefly hit … 779 mph for part of its trip, with a tailwind of 224 mph. And on Friday, yet another Norwegian plane used the jet stream to set a new speed record for a subsonic transatlantic crossing. The Boeing 787-9 Dreamliner went from New York’s JFK Airport to London’s Gatwick in 5 hours and 13 minutes. It beat British Airways’ 2015 record by three minutes and outpaced the standard crossing by half an hour. (The Concorde still holds the ultimate record among commercial aircraft: 2 hours, 53 minutes.)
So how does a standard Boeing jet carrying a full complement of passengers and luggage fly so fast? By taking advantage of a particularly vigorous jet stream, a current of air rushing from west to east, across the Atlantic. During Norwegian’s record-setting flight, that tailwind reached 202 mph and pushed a Boeing that usually cruises at 570 mph to 776 mph.
Airlines have long made use of the transatlantic jet stream to save time and fuel when flying from the US to Europe. “The airlines look at forecasted winds and they supply air traffic controllers with their preferred routing,” says Ian Petchenik, a spokesperson for FlightRadar24, which tracks flights all over the world.
17 Jan 2018, 0400 UTC. That rainbow in the middle marks wind speed, with red signifying the most intense part of the Jetstream.
The speed of sound at an altitude of 30,000 to 40,000 feet is roughly 670 mph. But Norwegian’s planes didn’t break the sound barrier. Those near-800-mph figures represent ground speed — how fast the aircraft is moving over land. Their air speed, which factors out the 200-mph wind boost, was closer to the 787’s standard Mach 0.85. (The older Boeing 747 can cruise at Mach 0.86, but is less efficient than its younger stablemate.) When talking supersonic, and breaking sound barriers, it’s all about the speed of the air passing over the wings, which in this case was more like 570 mph.