According to Jaiwon Shin, associate administrator of NASA's Aeronautics Research Mission Directorate, the plane will start
flying over populated areas in 2022.
Over a populated area with flimsy structures, that could be deadly, but in the more likely event of an explosion over the ocean, the effects would be relatively minor.
We've used the NASA Goddard Institute for Space Studies (GISS) climate model to examine the impact of a wetter stratosphere on climate and on
ozone over populated areas (this study did not look at polar ozone).
There are recommendations for not flying
drones over populated areas or moving vehicles, they're concerned about distracted driving, and there are requirements for flying them indoors.
The next FAA rule - making is slated for December, where regulators will open proceedings to decide how drones will be allowed to fly
over populated areas, a critical component of legal drone delivery.
A big problem with supersonic flight was that the sonic boom made it too loud to fly
over populated areas.
Unless you have obtained specific permission, Transport Canada recommends that you avoid flying a drone
over populated areas, moving vehicles, highways, bridges and busy streets.