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National Museum of Nuclear Science & History

Checklist for Loading Charge in Little Boy Aboard Enola Gay

It was not uncommon for B-29s to crash on takeoff from the airfield at Tinian Island during World War II. Overloaded by gasoline and bombs, the planes would be too heavy to get airborne before the runway ended. The Little Boy bomb weighed a massive 9,700 pounds. If the Enola Gay crashed on takeoff and Little Boy was already armed, the explosion could very well trigger Little Boy to detonate. After witnessing several B-29s crash on takeoff, ordnance expert Capt. William “Deak” Parsons decided it was safer to loading the gunpowder and detonator charges into Little Boy in the air. On August 5 – the day before the first atomic bombing mission was scheduled – Parsons practiced the delicate and difficult task of inserting the charges into an atomic bomb. This checklist shows the procedure for loading the charges in the bomb bay of the plane, and also the checklist to secure the bomb in case of an emergency landing. The bomb was fully armed only after the green plugs had been removed and the red plugs inserted, by Electronic Test Officer Morris Jeppson.

Document Type:
Deak Parsons's checklist for insert charges into Little Boy

Check list for loading charge in plane with special breech plug

(After all D-3 tests are completed)

  1. Check that green plugs are installed.
  2. Remove rear plate.
  3. Insert breech wrench in breech plug.
  4. Unscrew breech plug, place on rubber pad.
  5. Insert charge, 4 sections, red ends to breech.
  6. Insert breech plug and tighten home.
  7. Connect firing line.
  8. Install armor plate.
  9. Install rear plate.
  10. Remove and secure catwalk and tools.


Check list for emergency landing.

  1. Check that green plugs are installed.
  2. Install catwalk.
  3. Remove rear plate.
  4. Remove armor plate.
  5. Disconnect firing line.
  6. Insert breech wrench.
  7. Unscrew breech plug, (about 16 turns), remove, place on pad
  8. Remove charge, 4 sections, place in powder can and secure.
  9. Replace breech plug in breech, if there is time.



Plugs used to arm the Little Boy bomb by Morris Jeppson. Today the plugs are owned by philanthropist Clay Perkins.

Little Boy ready to be lifted into the Enola Gay

Capt. William "Deak" Parsons and Col. Paul Tibbets briefing the 509th Composite Group crews

Deak Parsons

Deak Parsons is decorated after the Hiroshima mission