Allan J. McDonald

Allan James McDonald (July 9, 1937 – March 6, 2021) was an American engineer, aerospace consultant and author. He was the director of the Space Shuttle Solid Rocket Motor Project for Morton-Thiokol.
In January 1986, he refused to sign off on a launch of the Space Shuttle "Challenger" which broke apart 73 seconds into flight. 
McDonald died in Ogden, Utah at the age of 83 on March 6, 2021. The cause of death was a cerebral hemorrhage caused by a fall.