One of the remaining original members of the Tuskegee Airmen—the first group of African-American pilots to serve in the U.S. military—passed away on Friday. Lieutenant Colonel Robert Friend was surrounded by family and friends when he succumbed to sepsis at 99 years old on June 21, according to CNN. His passing follows that of Dr. Granville Coggs, another Tuskegee veteran who died in May.

The Tuskegee Experience, an Army Air Corps program designed to train African-American pilots for combat, was established in 1941 by the Roosevelt Administration. The group, soon to become known as the Tuskegee Airmen, would eventually lead more than 15,000 air attacks during World War II and helped to persuade President Truman to desegregate the armed forces in 1948.

Born in South Carolina but raised in New York City, Friend took an interest in aviation while observing Zeppelin aircraft and constructing model planes. According to the Los Angeles Times, Friend himself flew 142 missions during the war, and would later see action in Korea and Vietnam.

His first wife's likeness can be seen in the form of the famous "Bunny" painting found on the side of the restored P-51 Mustang he once flew. He would retire as a lieutenant colonel after 28 years of service, although flying aircraft was not his only field of expertise: Friend directed Project Blue Book—a series of studies launched by the U.S. Air Force that dealt with UFO sightings. In a 2012 interview concerning the project, Friend told HuffPost, "I, for one … believe that the probability of there being life elsewhere in this big cosmos is just absolutely out of this world—I think the probability is there."

CNN reports that Friend's funeral will most likely be held the weekend of July 4.

[h/t CNN]