Observation planes often flew over Japanese cities to take photos and observe weather. A small flight of American bombers would have been an unremarkable sight to the people of Hiroshima, and the Air Service did not try to shoot these planes down, due to a shortage of aviation fuel.

Junko Morimoto was a 13-year-old schoolgirl in Hiroshima at the time of the bombings. She recalled that she had thought the planes were on a recon mission, since Hiroshima had been frequently-visited by photo-reconnaissance aircraft, usually F-13s (the photorecon variant of the B-29). As a result, she dismissed the sounds of the planes as nothing new.

...we heard the loud aircraft noise. At that time, we were very aware of the noises different aircraft made. I stood up and said it could be a B-29.

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