I'm not a pilot, only an ATC, but :
Is the sonic cruiser not intended for close to Mach 1 but sub-sonic speeds?
AND,
Travelling at speeds close to Mach 1 (but sub-sonic), and then entering an airmass of less density (low pressure or higher temp) can cause temporary super-sonic speed and thus sonic boom. Heard of this happening with mil jets at low level and causing damage to houses on the deck.
- Just a thought. -
SID