When did the crew know that they were dropping an atomic bomb?

Answer 1

The crews of the Enola Gay and Bockscar knew from the beginning the type of weapon they were dealing with, as they and other crew of the 509th Bomb Group had to train for months prior to the first delivery on Hiroshima. They needed to know this information to properly handle the weapon, know its capabilities so they could exit the drop area rapidly to avoid the shock wave, and for scientific monitoring. As the first bomb was the first used in combat, Bockscar was the photo and recording plane for the event.

Both crews also realized that what they were doing would likely end the war quickly, thus averting the already planned invasion of the main island of Honshu in the Japanese islands. This realization cannot be overstated or blown off by hindsight over 60 years later -projected invasion casualties were in the millions, as the Japanese military had told the Japanese that invading Allied forces would do terrible things to them, and all were given some type of military training, even women and children. From experience fighting the Japanese on the outer islands of Okinawa and Iwo Jima, the Allies knew that the invasion of Japan would be a very costly one in terms of human lives on both sides.

As one who has dealt with nuclear weapons in my own career, I will say this - everyone who handles them or is responsible for delivering them to the target in today's world understands fully the ramifications and consequences. This includes civilian leaders, and it is the main reason that nuclear war has been averted for so many years. However, with radical terrorists, the threat has changed - they do not have the same morals and responsible attitude that others do who are responsible for nukes. Also, not all countries are as responsible in handling them - North Korea is a prime example.