Dozens of white parachute canopies were blossoming in the freezing stratosphere as B-17s began plummeting toward the ground.
Above him, combat box formations of B-17 "Flying Fortresses" - named for their bristling defensive .50-caliber machine guns - were being swarmed by Luftwaffe fighters.
"When I pressed my face against the Plexiglas I saw German planes swirling around the higher groups," said Stevens, now 88. "It looked like a beehive of activity. "
An enemy fighter, belching smoke and flames, dropped past Stevens' crew position close enough to see the pilot before the aircraft continued a long descent into the earth.
"It looked like a movie," Stevens said. "It didn't look real. "
Though those desperate times belong to a passing generation, Southern California residents can get a visceral connection to the airmen of the Eighth Air Force on Saturday at the Long Beach Daugherty Field Airport by touring or even flying in the Liberty Foundation's B-17 "Memphis Belle," used in the 1990 movie with the same name.
The bomber is making its first West Coast tour in honor of the 70th anniversary of its namesake plane's crew completing their 25th and final mission in May 1943.
Stevens, a Temple City resident and 35-mission veteran, stepped back into his past on Monday when he climbed back on board for a B-17 flight. Until another flight earlier this year, Stevens had not been on a B-17 since the war.
Conditions were definitely different for this flight compared to then.
Instead of cruising above 25,000 feet in temperatures around 50 degrees below zero for as many as 11 hours, Stevens' flight was only a leg around Long Beach its port. The temperature was a milk-warm 70 degrees.
The venerable B-17 carried its passengers - sightseers and one former airman - with gusto, leaping off the Daugherty Field runway, the droning engines breaking into a teeth-rattling, penetrating roar as the pilots throttled up for takeoff.
After 30 minutes, Stevens was backing carefully out of a door behind the B-17's waist gunner position.
"Not as easy as I used to do that," he said with a chuckle.
During World War II, 12,731 B-17s were built. Only 12 survive today, according to Liberty Foundation lead pilot Ray Fowler of Carrollton, Ga.
He said the rarity of the workhorse bomber of the battle against Nazi Germany, along with the reality of operating costs that reach $1,400 for fuel alone, makes it more important than ever for people to come out and support the memory of the men who helped liberate Europe almost 70 years ago.
"We tell everyone the history of what they did," Fowler said. "The only way we survive is off donations and the goodwill of the public so we can see this aircraft fly and not parked as a museum piece."