February 19, 2019
While you were sleeping, a Boeing 787-9 twin jet airplane was ripping over Pennsylvania at more than 800 mph.
At least, kind of.
A curiously strong jet stream, as noted by the Washington Post and weather experts all over, was sweeping across the northeast on Tuesday evening.
One Virgin Atlantic flight, heading from Los Angeles to London, happened to pass over Pennsylvania as the winds were particularly robust, so much so that it peaked around 801 mph:
That #jetstream! 🌬️ Highest wind speed at 250 millibars in the period of record for those locations near NYC, and for a jet ✈️ over PA last evening an *801* mph ground speed #wow (h/t @gdimeweather, https://t.co/MIqBu7mHNf) pic.twitter.com/RaL2HRQ5Z1— Stu Ostro (@StuOstro) February 19, 2019
One Twitter user, Peter James, said he’d never seen a tailwind of 200 mph during his time as a commercial pilot:
Almost 800 mph now never ever seen this kind of tailwind in my life as a commercial pilot !! (200 mph tailwind ) pic.twitter.com/0XGTkEP9EB— Peter James (@jetpeter1) February 19, 2019
Keep in mind, of course, that the speed of sound is about 758 mph.
So that does mean there was a sonic boom over Pennsylvania on Tuesday night? Unfortunately, no, because the 801 mph figure was the plane’s ground speed, not its air speed.
A plane’s ground speed, according to the Post, is “the speed an airplane has relative to a point on the ground.” A plane’s air speed is simply how fast the plane would be moving without the wind. In order to break the speed of sound, the Post explained, a plane’s air speed would have to push 758 miles per hour rather than its ground speed.
And looking at it another way, the ground speed is how fast you’d have to be moving on the ground in order to keep pace with the plane in the air.
The plane that passed over Pennsylvania on Tuesday night has maximum propulsion of 587 mph, according to the Post, which means that jet stream was doing some serious work.
Whether it was a ground speed record for a Boeing 787-9 is unclear. The Post believes it was, and points to a year-old story about a ground speed record of 776 mph on a Norwegian Air flight to London. The website GroundSpeedRecords.com, however, says the top record belongs to an American Airlines flight from January 2018 which hit a ground speed of 835 mph.
In any case, a very fast airplane flew over Pennsylvania last night, which is neat.