I had a 175 mph jet stream tailwind flying from Manila to SFO on Dec. 31, and BA had a 200 mph assist from Heathrow to JFK on Jan. 7.
Although the article says the BA plane was approaching the speed of sound, that’s not strictly accurate.
Somewhere the speed of sound could be 761 mph, but it was only the ground speed that was high. The actual airspeed, relative to the jet stream, was still only around 500 mph.
Since currently-flying airliners are not designed to fly near or beyond the sound barrier, you wouldn’t want to even get close to the actual speed of sound in a jet stream, which can be very turbulent. (A delta-shaped wing with flight controls tested at trans-sonic and supersonic speeds are needed.)
I vaguely remember tailwinds higher than 200 mph on the same route before, but don’t recall the actual numbers (over 800 mph ground speed.) It’s common on that route to see short return trips. I should make a note next time, as that is near the highest recorded speed according to wikipedia.
It’s amazing to me that one can fly from Asia to USA in 11 to 12 hours, weather permitting.