After a mid-air collision with a fighter plane during a practice exercise off Tybee Island, Georgia, a U.S. Air Force bomber jettisoned a Mark 15 nuclear bomb, which was presumed lost.

The Tybee Island mid-air collision was an incident on February 5, 1958, in which the United States Air Force lost a 7,600-pound (3,400 kg) Mark 15 nuclear bomb in the waters of Tybee Island near Savannah, Georgia, United States. During a night practice exercise, an F-86 fighter plane collided with the B-47 bomber carrying the large weapon.

Tybee Island is a city and a barrier island in Chatham County, Georgia, 18 miles (29 km) east of Savannah. The name is used for both the city and the island, but geographically the two are not identical: only part of the island's territory lies within the city, while the rest is unincorporated.

The United States Air Force (USAF) is the air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its origins to 1 August 1907, as a part of the United States Army Signal Corps, the USAF was established by transfer of personnel from the Army Air Forces with the enactment of the National Security Act of 1947. It is the second youngest branch of the United States Armed Forces and the fourth in order of precedence. The United States Air Force articulates its core missions as air supremacy, global integrated intelligence, surveillance and reconnaissance, rapid global mobility, global strike, and command and control.

The Mark 15 nuclear bomb, or Mk-15, was a 1950s American thermonuclear bomb, the first relatively lightweight thermonuclear bomb created by the United States.