An aircrew ferries an unarmed 1940 series Boeing B-17D Flying Fortress heavy bomber, named the Mary-Ann, across the Pacific to the United States Army Air Forces base at Hickam Field.

On December 6, 1941, at Hamilton Field, near San Francisco, the crew of the Mary-Ann, a U.S. Army Air Corps B-17D, are ordered across the Pacific to Hawaii, one of a flight of nine Flying Fortress bombers.

Master Sergeant Robbie White, the Mary-Ann's crew chief, is a long-time veteran, whose son Danny is an officer and pursuit (fighter) pilot.

[Note 1] In its aftermath, the tired crew is ordered, with little rest, to fly first to Wake Island, and finally to Clark Field in the Philippines, both also still under Japanese attack.

They take along two passengers: fighter pilot Lieutenant Thomas "Tex" Rader and a small dog, "Tripoli", the Marines' mascot on Wake Island.

Soon after, Quincannon volunteers his bomber (the only one available) to attack a Japanese invasion fleet, but the Mary-Ann is swarmed by enemy carrier fighters and forced to abort after losing two engines.

Having told the now dying Quincannon that the Mary-Ann is ready to fly, the crew works feverishly through the night to repair their bomber, scavenging parts from other damaged B-17s, as the Japanese Army closes in.

As they head to Australia, with Rader as the reluctant pilot and the wounded Williams as co-pilot, they spot a large Japanese naval invasion task force directly below.

The crew radios the enemy's position and circles until reinforcements arrive; the Mary-Ann then leads the attack that devastates the Japanese fleet (this dramatic sequence mirrors the real events of the Battle of the Coral Sea).

[5] Later in the war, a bombing attack on Tokyo is finally announced to a roomful of bomber crews, among them several familiar faces from the Mary-Ann, including Rader, now a B-17 pilot.

(The Japanese aircraft were detected by the Opana radar site on northern Oahu and reported to the Fort Shafter Intercept Center but was dismissed by the Watch Officer as being this flight of B-17s scheduled to arrive at Hickam Field around the same time as Japan’s attack.)

[5] Development of the film was concurrent with scriptwriting by Dudley Nichols, with some characters based on Air Corps personnel Hawks met while traveling to Washington, D.C., to confer with Arnold and the War Department Motion Picture Board of Review.

Sherman remained as second-unit director to assist with completion of the film, which wrapped on 26 October 1942, failing to shoot 43 pages of script and 33 days over schedule, too late to meet its 7 December release date.

He was at Randolph Field, Texas, in the process of appearing as himself in the Academy Award-winning short film Beyond the Line of Duty when he assisted on Air Force.

As detailed in Walter Lord's book Day of Infamy, later investigations proved that no Japanese-American was involved in any kind of fifth column sabotage during the Pearl Harbor attack or later.

In the film, however, a member of the Mary-Ann's aircrew makes a improvised field modification, removing the tail cone and creating a manned, single machine gun position.

As detailed in Herbert S. Brownstein's Flying Fortress volume The Swoose: Odyssey of a B-17, a few B-17D aircrews field-installed a remotely controlled (via a pullcord) .30 caliber machine gun in their tails.

[17] Air Force placed third (behind The Ox-Bow Incident and Watch on the Rhine) as the best film of 1943 selected by the National Board of Review of Motion Pictures.

[1] Air Force editor George Amy won the 1944 Academy Award for Best Film Editing, defeating his counterparts on Casablanca, For Whom the Bell Tolls, Five Graves to Cairo, and The Song of Bernadette.

An Air Force plot detail is loosely referenced in the film Pulp Fiction (1994) during Christopher Walken’s monologue playing Captain Koons.