The first attack wave of 183 planes was launched north of O‘ahu, commanded by Captain Mitsuo Fuchida. Six planes failed to launch due to technical difficulties. It included:
01. 1st Group (targets: battleships and aircraft carriers)
- 50 Nakajima B5N bombers armed with 800 kg (1760 lb) armor piercing bombs, organized in four sections
- 40 B5N bombers armed with Type 91 torpedoes, also in four sections
02. 2nd Group — (targets: Ford Island and Wheeler Field)
- 54 Aichi D3A dive bombers armed with 550 lb (249 kg) general purpose bombs
03. 3rd Group — (targets: aircraft at Ford Island, Hickam Field, Wheeler Field, Barber’s Point, Kaneohe)
- 45 Mitsubishi A6M fighters for air control and strafing
As the first wave approached O‘ahu a U.S. Army SCR-270 radar at Opana Point near the island's northern tip (a post not yet operational, having been in training mode for months) detected them and called in a warning. Although the operators reported a target echo larger than anything they had ever seen, an untrained officer at the new and only partially activated Intercept Center, Lieutenant Kermit A. Tyler, presumed the scheduled arrival of six B-17 bombers was the source. The direction from which the aircraft were coming was close (only a few degrees separated the two inbound courses), while the operators had never seen a formation as large on radar; they neglected to tell Tyler of its size, while Tyler, for security reasons, could not tell them the B-17s were due (even though it was widely known).
Several U.S. aircraft were shot down as the first wave approached land, and one at least radioed a somewhat incoherent warning. Other warnings from ships off the harbor entrance were still being processed or awaiting confirmation when the attacking planes began bombing and strafing. Nevertheless it is not clear any warnings would have had much effect even if they had been interpreted correctly and much more promptly. The results the Japanese achieved in the Philippines were essentially the same as at Pearl Harbor, though MacArthur had almost nine hours warning that the Japanese had already attacked at Pearl and specific orders to commence operations before they actually struck his command.
The air portion of the attack on Pearl Harbor began at 7:48 a.m. Hawaiian Time (3:18 a.m. December 8 Japanese Standard Time, as kept by ships of the Kido Butai), with the attack on Kaneohe. A total of 353 Japanese planes in two waves reached O‘ahu. Slow, vulnerable torpedo bombers led the first wave, exploiting the first moments of surprise to attack the most important ships present (the battleships), while dive bombers attacked U.S. air bases across O‘ahu, starting with Hickam Field, the largest, and Wheeler Field, the main U.S. Army Air Force fighter base. The 171 planes in the second wave attacked the Air Corps' Bellows Field near Kaneohe on the windward side of the island, and Ford Island. The only aerial opposition came from a handful of P-36 Hawks and P-40 Warhawks.
Men aboard U.S. ships awoke to the sounds of alarms, bombs exploding, and gunfire prompting bleary eyed men into dressing as they ran to General Quarters stations. (The famous message, "Air raid Pearl Harbor. This is not drill.", was sent from the headquarters of Patrol Wing Two, the first senior Hawaiian command to respond.) The defenders were very unprepared. Ammunition lockers were locked, aircraft parked wingtip to wingtip in the open to deter sabotage, guns unmanned (none of the Navy's 5"/38s and only a quarter of its machine guns, and only four of 31 Army batteries got in action). Despite this and low alert status, many American military personnel responded effectively during the battle. Ensign Joe Taussig got his ship, USS Nevada, underway from dead cold during the attack. One of the destroyers, USS Aylwin, got underway with only four officers aboard, all Ensigns, none with more than a year's sea duty; she operated at sea for four days before her commanding officer managed to get aboard. Captain Mervyn Bennion, commanding USS West Virginia (Kimmel's flagship), led his men until he was cut down by fragments from a bomb hit to USS Tennessee, moored alongside.
Gallantry was widespread. In all, 14 officers and sailors were awarded the Medal of Honor. A special military award, the Pearl Harbor Commemorative Medal, was later authorized for all military veterans of the attack.