One of Richard Branson's Virgin Atlantic flight set a new ground speed record for a Boeing 787-9 while over Pennsylvania yesterday...
The typical cruising speed for a plane of this size is only around 560 mph, which is a long way off of the speed of sound’s 767 mph (although the speed of sound does vary based on altitude, air temperature, pressure, and on and on, and that 767 mph figure is based on a reading at sea level under standard conditions).And that’s exactly why there was no sonic boom for this 801 mph flight.
Passengers aboard got a bonus they can brag about to their friends......Ben