Slashdot Mirror
Record-Breaking Jet Stream Accelerates Air Travel, Flight Clocks In At 801 MPH (cbsnews.com)
pgmrdlm quotes CBS News: On Monday night, the river of air 35,000 feet above the New York City area, known as the jet stream, clocked in at a blazing 231 mph. This is the fastest jet stream on record since 1957 for the National Weather Service in Upton, New York — breaking the old record of 223 mph, according to NWS forecaster Carlie Buccola. This wind provided a turbo boost to commercial passenger planes along for the ride. With the help of this rapid tailwind, Virgin Atlantic Flight 8 from Los Angeles to London hit what could be a record high speed for a Boeing 787: 801 mph over Pennsylvania at 9:20 p.m. Monday night...
"The typical cruising speed of the Dreamliner is 561 mph," CBS News transportation correspondent Kris Van Cleave points out. "The past record for the 787 is 776 mph set in January 2017 by a Norwegian 787-9 flying from JFK to London Gatwick. That flight set a record for the fastest subsonic transatlantic commercial airline flight -- 5 hours and 13 minutes, thanks to a 202 mph tailwind."
FlightAware, a global aviation data services company, reminds CBS that even a 100 mph increase in the jet stream can shorten a flight by an hour.
"The typical cruising speed of the Dreamliner is 561 mph," CBS News transportation correspondent Kris Van Cleave points out. "The past record for the 787 is 776 mph set in January 2017 by a Norwegian 787-9 flying from JFK to London Gatwick. That flight set a record for the fastest subsonic transatlantic commercial airline flight -- 5 hours and 13 minutes, thanks to a 202 mph tailwind."
FlightAware, a global aviation data services company, reminds CBS that even a 100 mph increase in the jet stream can shorten a flight by an hour.
Airline planners would likely have the routes deviate in the opposite direction to not be flying in the strongest part of the jetstream, so it's not an equal advantage / disadvantage for both directions.
You may be interested to see the jetstream maps for how wide it typically is: generally several hundred miles wide
Mach number is the ratio of the speed of an object thorough an air mass (aka, airspeed) to the speed of sound through the same air mass. The speed of sound you cite is the speed of sound in dry air at 20 C. Since the airliner was flying at 35,000 feet, or 10.7 km, we can assume (using the standard lapse rate of 6.5 C per kilometer) a much lower temperature of approximately -50 C, and thus a significantly lower speed of sound.
Having said all that, it is meaningless to speak of Mach in relation to ground speed. Note the quote from TFS: "The past record for the 787 is 776 mph set in January 2017 by a Norwegian 787-9 flying from JFK to London Gatwick. That flight set a record for the fastest subsonic transatlantic commercial airline flight -- 5 hours and 13 minutes, thanks to a 202 mph tailwind."