Supersonic passenger planes, which may cut travel time by half, could return to US skies

Supersonic passenger flights could return to US skies as country's aviation body FAA has proposed replacing speed-based restrictions introduced in 1973 with new noise-based rules. Such planes fly faster than speed of sound and could potentially cut travel times by up to half. However, concerns over sonic boom, a thunder-like sound reaching the ground led to overland restrictions in 1973.