The first supersonic flight was in 1947. It was just above the speed of sound. Which altitude would you expect Captain Yeager to have used for his flight?

Select one:
a. 85,000 m (where meteor showers originate)
b. Sea level
c. 1,000 m
d. 13,700 m (within altitude used by commercial planes today)

2 answers

higher altitude ("thinner" air) means lower speed of sound

d. looks good

b. and c. too low , a. too high
I thinks it’s b