Carrier strikes are generated in waves

Nagumo's first wave comprised 21 Zero fighters, 21 Val dive bombers, and 22 Kate torpedo aircraft. Two Kates served only as navigation aids, and nine fighters diverted to engage incoming aircraft, leaving an effective attacking package of twelve fighters, 21 dive bombers, and twenty torpedo bombers. Hornet's first wave combined eight Wildcats, fifteen Dauntless dive bombers, and six Avengers; Enterprise followed with about twenty aircraft, and Hornet launched another 26. The larger Japanese waves combined contributions from multiple carriers, while each American carrier also had to retain aircraft for defense. A practical launch of roughly twenty to thirty aircraft drew from an air group that also supported later sorties. Follow-up strikes were prepared before the first attacks had reached their targets, because one wave might miss or fail to disable the enemy force. Holding an enormous combined strike over the ships would consume fuel while aircraft waited for the rest to launch. American launches ran roughly twenty to thirty minutes behind the Japanese, with the interval depending on which aircraft and launch endpoints were compared.