A short explanation, if practicable, would be gratefully received.
I'll just quote the relevant passages from the book.
[QUOTE="Shattered Sword" by Jonathan Parshall and Anthony Tuly]
... Japanese doctrine prescribed attacking targets with groups of aircraft containing elements of all three disciplines—fighters, dive-bombers, and carrier-attack planes (acting in either a torpedo- or level-bombing capacity). In multidivision attacks, an entire carrier division would contribute matched air groups to the overall effort, launching both of its dive-bomber units (for instance), while a second division would launch its two carrier attack bomber units. These four squadrons—seventy or more combat aircraft—would be escorted by fighters contributed by all four carriers. On follow-up strikes, the air group compositions would be reversed, with the first division sending up its torpedo bombers and the second contributing its dive-bombers. The result was that Japanese carriers could launch large, well-balanced strikes against their enemies.
To support this favored mode of attack, the Japanese evolved a practice known as "deckload spotting," wherein a carrier would launch about half its air group at any one time—a complete attack unit of some sort (torpedo- or dive-bombers) and usually a
chutai [a group of 6-9] of fighters. With this initial force launched, the carrier would still retain half of its striking power for follow-up operations. This practice probably grew out of the impracticality of launching the carrier's complete air group. Such a group would need to be spotted and launched in two separate deck cycles, thus keeping the first half of the strike package waiting in the air over the force (and burning precious fuel) while the second portion was spotted and launched—an operation that could take at least half an hour to complete. With a deckload strike, though, the Japanese launched a group that fit comfortably on the flight deck and still had sufficient tactical weight ...
Deckload strikes had worked well for the Japanese thus far in the war, because they left little question as to each carrier's contribution and lent themselves well to aggregating aircraft for an initial strike. Interestingly, this practice stood in direct contrast with how the U.S. Navy ran its carriers. U.S. flattops could, and occasionally did, send their entire air group aloft, although the complications this introduced into the deck cycles of their carriers would plague them throughout the coming battle.
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