Why didn't Bock get to fly his own bomber, Bockscar?

First, a little background.

Most people are aware that the bomber Enola Gay delivered the first atomic weapon to Hiroshima. Fewer people are aware that Bockscar (sometimes called Bock’s Car) delivered the second nuclear weapon, Fat Man, to Nagasaki on August 9, 1945.

The question relates to why didn’t Captain Frederick Bock fly his own plane (Bockscar) during the second run.

The answer relates to the purposes of the planes for each occasion.

Major Charles W. Sweeney had used Bockscar for more than 10 training and practice missions (it wasn’t Bock’s airplane after all, just named after him).

Normally, Sweeney and his crew piloted an aircraft called The Great Artiste, and this plane provided the instrumentation and observation support for the drop on Hiroshima.

For the second mission to Japan, Sweeny and his crew were chosen to deliver Fat Man while Bock and crew were chosen to provide observation support. Weather considerations caused the fight to be moved from August 11 to August 9. This didn’t leave enough time to move the complex instrumentation equipment from The Great Artiste to Bockscar, so the two crews traded planes with each other for the historic flight.

The Bockscar plane is preserved at the National Museum of the United States Air Force in Dayton, Ohio.