US Air Force Broken Arrow Event - MK 17
MK 17 Accident - May 22, 1957
On May 22, 1947 a B-36 Air Force Bomber was flying from Briggs AFB in El Paso, Texas to Kirtland AFB in Albuquerque, New Mexico when the crew accidentally dropped the MK 17 Bomb, the largest hydrogen bomb of the time!
By only 8 seconds, the full nuclear fission did not detonate. The bomb landed in a remote pasture and the only casualty was a grazing cow.
The crew were told to keep the incident a secret and no details were released until 1986.