What truth have I stretched? The last time a Boeing jetliner flew past its limits it broke up in mid flight. Speed on a passenger jet is max 313 knots just for bird impact protection on takeoff, that doesn't mean it can go max speed. The top speed of 610 MPH is the speed at 30K altitude if exceeded will cause breakup. There is so much more drag at sea level that the top speed is seriously reduced. Even my little Bonanza flies 30% faster at altitude than it does at takeoff and it flies max 18K feet. Dynamic pressure is proportional to speed, so if there is 25 pounds of pressure per foot at 100 MPH at sea level, then there would be 100 Pounds of pressure at 200 MPH, and at 500 MPH it would be about 625 Psf. Dynamic pressure is what the speed pitot reads. The airliner cannot go as fast as they say, they are using the deceptive "Airspeed" and not the ground speed when they give those numbers.