Robert Friend, a decorated fighter pilot who flew 142 combat missions with the fabled Tuskegee Airmen during World War II, then became an expert on missile systems and directed Project Blue Book, the classified Air Force investigation into unidentified flying objects, died June 21 at a hospital in Long Beach, Calif. He was 99.

The cause was sepsis, said his daughter Karen Crumlich.

Col. Friend was one of the last surviving Tuskegee Airmen, who took to the skies in World War II as the first African American military aviators. The roughly 1,000 black pilots who were trained in the program flew 15,000 combat sorties, destroyed 260 enemy aircraft and received 150 decorations of the Flying Cross and Legion of Merit, fighting the Nazi Luftwaffe while striking a blow against racism back home.

The unit’s success was widely credited with paving the way for the integration of the military after World War II, and in 2007, Col. Friend and his comrades were awarded the Congressional Gold Medal, recognized for their “unique military record that inspired revolutionary reform in the Armed Forces.”

Only 11 Tuskegee Airmen who flew combat missions in the Mediterranean survive, in addition to an unknown number of maintenance and support staff — women as well as men, including Native Americans, Latinos and other people of color — according to the veterans organization Tuskegee Airmen Inc.

The son of an Ecuadoran immigrant who served in the Army during World War I, Col. Friend flew a P-47 before taking the controls of a P-51 Mustang, a single-seat fighter that he nicknamed Bunny, for his girlfriend and future wife, and decorated with the distinctive red rudder, nose and wing tips that identified many of the Tuskegee Airmen’s planes.

Frequently assigned to protect “Flying Fortress” bombers, Col. Friend served as a wingman for Tuskegee commander Benjamin O. Davis — who later became the first black general in the Air Force — and received the Distinguished Flying Cross for his actions on Oct. 6, 1944, when he strafed airfields in German-occupied Greece.

In a 28-year military career, he went on to serve as an operations officer in the Korean and Vietnam wars; worked on the Titan, Atlas and Delta rocket programs; and from 1958 to 1963 oversaw Project Blue Book, which collected and analyzed more than 12,000 reports of flying saucers and other mysterious airborne objects.

Col. Friend later said that he believed “the probability of there being life elsewhere in this big cosmos is just absolutely out of this world,” telling HuffPost in 2012, “I think the probability is there.” During his tenure, he said, he twice recommended that a federal agency outside of the military take on the study of UFOs.

Begun in 1952, Project Blue Book was shut down in 1969 and later declassified by the Air Force, which said that the program failed to uncover “any technological developments or principles beyond the range of present-day scientific knowledge” or to find any evidence of “extraterrestrial vehicles.”

Clouds, birds, jet planes and “swamp gas” were credited with spurring many of the unusual sightings, although 701 incidents remain unexplained. The program gained renewed attention in 2017, after the New York Times disclosed the existence of a secret new UFO program — the Advanced Aerospace Threat Identification Program — and inspired a popular History television series, “Project Blue Book,” which premiered in January.

Although Col. Friend occasionally discussed Project Blue Book in interviews, he was far better known for his record as a Tuskegee Airman, notably for a two-week stretch when he twice averted disaster.

Striking an oil barge in Germany on Dec. 14, 1944, he unleashed a barrage of 50-caliber bullets that triggered an enormous, mushroom-shaped explosion, nearly taking down his aircraft. “The flame completely engulfed the diving ship,” the Pittsburgh Courier reported at the time. “Friend said it was sort of like being in hell. He managed to pull his ship out at the last moment.”

Days later, he faced bad weather and mechanical difficulties while flying over Italy. Disoriented in the darkness, praying to avoid crashing into a mountain or ejecting over the water, he took his chances and bailed out — and recalled in a 2006 lecture that he found himself parachuting toward a mountain.

“I hit the side of the mountain, slid down to the ground and saw a woman running to me with a knife in her hand,” he said, according to a Washington Post report. An alarmed Col. Friend soon found that she was no Nazi sympathizer. In an act of wartime desperation, he said, she simply “wanted the silk from my parachute.”

The oldest of four children, Robert Jones Friend was born in Columbia, S.C., on Feb. 29, 1920, and raised in New York City, where he developed an interest in aviation while watching Zeppelin airships and building model planes.

He studied at Lincoln University, a historically black school in Oxford, Pa., and received a private pilot’s license before applying in 1942 to enter the newly formed African American aviation program, part of the Army Air Forces and based at the Tuskegee Institute in Alabama.

Col. Friend served with the 332nd Fighter Group in Europe, receiving honors including the Bronze Star Medal and the Air Medal. He later studied astrophysics at the Air Force Institute of Technology and business at the University of California at Los Angeles.

After retiring from the Air Force in 1971, he worked as a consultant on the development of missile systems and space-station components, and competed in national bridge tournaments near his home in Irvine, Calif.

His marriages to Doris “Bunny” Goodwin and Kathryn Ann Holland ended in divorce, and his wife of more than 50 years, the former Anna Rice, died in 2010. Col. Friend is also predeceased by a son, Darryl Friend, from his second marriage.

Survivors include two children from his first marriage, Thelma Hoffman and Robert Friend Jr.; three children from his second, Michael Friend, Debra Carter and Dana Friend; a daughter from his third marriage, Karen Crumlich; an adopted daughter, Clara Ann Browning, from Rice’s previous marriage; 18 grandchildren; 32 great-grandchildren; and 14 great-great-grandchildren.

Into his 90s, Col. Friend appeared at 20 to 30 speaking engagements each year, answering questions about the Tuskegee Airmen at schools, community centers and the Palm Springs Air Museum in California, where he sometimes greeted visitors while sitting in front of a restored P-51 decorated to look like his old plane, Bunny.

He had encountered racism during the war, he told the Palm Springs Desert Sun, including moments when he felt less than welcome by white comrades who refused to bunk with him in Sicily. But he said he viewed himself less as a racial path-breaker than as a pilot, telling the newspaper: “I never felt that I was anything but an American doing a job.”