First Attack Wave
The Hawaii Operation was planned to consist of two waves of aircraft hitting Pearl Harbor about 30 minutes apart. The First Attack Wave was led by Lieutenant Commander Mitsuo Fuchida (Fuchida, Mitsuo) in person. It approached the north of Oahu, Kahuku Point, where the radar at Opana observed it, at about 0735 on 7 December. The wave then divided to pass down the middle of the island and around the west. The Second and Third Groups, fighters and dive-bombers, went down the middle and the First Group under Fuchida, torpedo and horizontal bombers, went down the western shore. By 0740 Fuchida had concluded that surprise had been achieved and fired a flare as a signal. It was either not seen or not acted on, so a second flare was used which led to the dive-bombers rushing forward. In the event it made no difference. The torpedo bombers cut inland and the horizontal bombers curled around the shore to the south. At 0749 Fuchida gave his radio operator orders to send the attack signal: ""To, To, To."" This was the first syllable of the word totsugekiseyo - ""charge"". At 0750 the other half of the wave transmitted a similar signal. As there was still no American reaction, Fuchida sent the message to indicate to the First Air Fleet that they had succeeded - ""Tora, Tora, Tora."" - Tiger, Tiger, Tiger.
The First Attack Wave was made up as follows:
First Group: 1st Attack Unit; 2nd Attack Unit; 3rd Attack Unit; 4th Attack Unit; 1st Torpedo Unit; 2nd Torpedo Unit; 3rd Torpedo Unit; 4th Torpedo Unit.
Second Group: 15th Attack Unit; 16th Attack Unit.
Third Group: 1st Fighter Combat Unit; 2nd Fighter Combat Unti; 3rd Fighter Combat Unit; 4th Fighter Combat Unit; 5th Fighter Combat Unit; 6th Fighter Combat Unit.
You can learn more about the First Attack Wave in the following Osprey book: