[C19fan]

The 801 MPH is ground speed not airspeed. Mach 1 is based on airspeed not motion relative to the gound.

[Blue Jays]

I was on a transcontinental flight years ago and it just felt like we were absolutely hurtling through the air, yet simultaneously calm.
The pilot came on and announced we were doing a remarkable 750 mph (ground speed) due to a very beneficial and efficient tailwind. It was something to behold.
Very fun, indeed. While disembarking he shared it was the fastest elapsed time he had ever completed that route. So cool!

[Sir_Ed]

So the sound barrier changes depending on how fast the airstream blows?

So, this plane, to break the sound barrier, would’ve had to have been going 230 mph faster?

Interesting, I didn’t know that!