Horizontal bombing
Both dive bombing, torpedo bombing and bombing by aircraft in level flight, horizontal bombing, were carried out by the Japanese at Pearl Harbor. Horizontal bombing was notoriously inaccurate but was vital should the torpedo bombers, obliged to approach at near-stalling speed, fail. Intensive training increased Japanese accuracy from high altitude (between 10 and 15,000 feet) from 10% to 50%. To penetrate the armored decks of American battleships the Japanese converted heavy, 800kg, 15.7-inch, artillery shells into bombs by fitting fins. The aircraft used were Nakajima B5N2 Kates.
See also: Dive-bomber; Kate; Pearl Harbor
You can find out more about bombing techniques in the following Osprey books:
AIRCRAFT OF THE ACES 22 Japanese Navy Aces 1937-45; ELITE 46 US Army Air Force 1; AIRCRAFT OF THE ACES 13 Japanese Army Aces 1937-45