The crew of the Enola Gay poses in the Mariana Islands during World War II. Navigator Theodore “Dutch” VanKirk, standing at second from left, died July 28 at 93. (U.S. AIR FORCE/AP)

The next day was Aug. 6, 1945, and Theodore “Dutch” VanKirk was supposed to be sleeping. Instead, he passed the night playing cards with two friends in the Army Air Forces, a bombardier named Tom Ferebee and pilot Paul Tibbets.

“I don’t know how they expect to tell you that you’re going out to drop the atom bomb and not know if it’s going to work or if it’s going to blow up the airplane, and then tell you to go get some sleep,” Mr. VanKirk recalled years later. “I wasn’t able to sleep.”

Before dawn, he took his place as the navigator in the Enola Gay. At 24, he was the veteran of nearly 60 combat missions in World War II. His charts were ready. The outlines of the Pacific islands and the positions of the stars would be his guide.

Five and a half hours after take-off — just 15 seconds behind schedule — the B-29 Superfortress arrived at its destination in Japan. Mr. VanKirk recognized the landmarks of Hiroshima, including the T-shaped Aioi Bridge that was their precise target.

“All I had to do was sit there and wait,” Ferebee, the bombardier, later told a newspaper interviewer. “Dutch had us going straight for it.”

At 8:15 a.m. local time, the bomb, known as “Little Boy,” fell from the belly of the plane. It was the first atomic bomb used in war. An estimated 140,000 died from its explosion and aftereffects. Three days later, the United States dropped another atomic bomb, called “Fat Man,” on the city of Nagasaki. Together, the attacks hastened Japan’s surrender and marked the beginning of a new era in war.

Mr. VanKirk, who was widely reported to be the last survivor of the 12-member Enola Gay crew, died July 28 at a retirement community in Stone Mountain, Ga. He was 93 and had recently developed vascular disease, said his son Tom VanKirk.

Dutch VanKirk was serving stateside as a navigation instructor in 1944 when he received a call from Tibbets, his former commanding officer in Europe and the soon-to-be commander of the Enola Gay. Mr. VanKirk recalled the conversation in an interview years later with Time magazine.

“We’re going to do something that I can’t tell you about right now,” Tibbets explained, “but if it works, it will end or significantly shorten the war.”

“Oh, yeah, buddy,” Mr. VanKirk recalled thinking. “I’ve heard that before.”

The assembled crew convened in Utah to train for the secret mission. The words “atomic” and “nuclear” were not used, Mr. VanKirk later recalled. He said he deduced the nature of his cargo after contemplating the estimates of the weapon’s force, observing the physicists on site and putting “two and two together.”

The crew members knew that after the bomb was released, the plane would lurch from the loss of weight. And so it happened. Tibbets pulled a sharp turn and swift getaway to escape the force of the blast.

Mr. VanKirk recalled counting with the crew members “one thousand one, one thousand two” to 43 seconds — the length of time predicted to elapse between release and explosion. The men braced themselves for the possibility of a dud. Then came a shock wave, and another.

“We turned to where we could look out and see the cloud, where the city of Hiroshima had been,” he told the New York Times decades later. “The entire city was covered with smoke and dust and dirt. . . . I describe it looking like a pot of black, boiling tar. You could see some fires burning on the edge of the city.”

In that moment, Mr. VanKirk said, they believed the war was over. The attack on Nagasaki was still to come, however, with an additional 80,000 deaths. Days later, the Japanese surrendered.

Theodore Jerome VanKirk, the son of a truck driver and a homemaker, was born Feb. 27, 1921, in Northumberland, Pa. While in the Army Air Forces, where he attained the rank of major, he received decorations including the Silver Star, the Distinguished Flying Cross and numerous awards of the Air Medal, according to his family.

After his discharge, he enrolled at Bucknell University in Lewisburg, Pa., where he received a bachelor’s degree in 1949 and a master’s degree the next year, both in chemical engineering. He worked for 35 years with the DuPont chemical company as a chemical engineer and in sales and marketing.

In 1943 — after his 57 combat missions primarily in Europe and before his single mission in the Pacific — Mr. VanKirk married Mary Jane Young. She died in 1975. His second wife, Imogene Cumbie Guest, died in 2012 after more than three decades of marriage.

Survivors include four children from his first marriage, Tom VanKirk, named after Ferebee, of Pittsburgh; Larry VanKirk of Charlotte; Vicki Triplett of Atlanta; and Joanne Gotelli of Sacramento. Other survivors include seven grandchildren and two great-grandchildren.

In later years of his life, Mr. VanKirk, like many of his former crew members, was asked how he felt about his mission in the final days of World War II. He said that he was “proud to be on the Enola Gay” because it had saved lives by ending the war.

“If you were living in Hiroshima or Nagasaki at the time the bombs were dropped, you would have great difficulty accepting this,” he told the San Francisco Chronicle. But, he added, “I’m sure that many more lives were saved than lost.”

An earlier version of this article incorrectly reported that the atomic bomb was dropped on Hiroshima at 9:15 a.m. local time. It was dropped at 8:15 a.m. local time. The article has been corrected.