"He used to tell us that his engine tapped him on the shoulder and said, 'Lt. Stewart, I'm going to quit right here and now at 6,000 feet. Let's see what you can do,' " his son Louis recalled.
The injuries Mr. Stewart suffered in the crash prevented him from serving overseas, his son said.
The success of the 992 African American airmen trained at an Army airfield near Tuskegee, Ala. - they downed 111 enemy planes - helped to clear the way for desegregation of the U.S. military.
On Philadelphia's Tuskegee Airmen Day in 1993, Mr. Stewart recalled in an Inquirer interview how deep racism ran in the military during World War II.
He said that a white flight instructor at Tuskegee, a captain from Mississippi, crashed during a training run. At the hospital, the captain needed a transfusion and only "black blood" was available.
"His wife said she would rather let him die," Mr. Stewart said. The officer was flown to Maxwell Air Force Base to get "white blood."
A South Carolina native, Mr. Stewart lived in Manayunk after coming to Philadelphia with his family in 1930. He graduated from Roxborough High School in 1940. He earned a bachelor's degree from Philadelphia College of Pharmacy and Science, now the University of the Sciences, in 1951.
He became a staff pharmacist at Philadelphia General Hospital and was named head of its pharmacy department in 1967. After the hospital closed in 1976, he worked for the city until he retired in 1982.
Mr. Stewart was active with several organizations, including the Greater Philadelphia Chapter of the Tuskegee Airmen and the Military Order of the World Wars.
For more than 50 years, he was a member of Galilee Baptist Church in Roxborough, where he taught Sunday school.
In addition to his son, Mr. Stewart is survived by his wife of 54 years, Viola; another son, Nathaniel Jr.; and five grandchildren.
Services will be at 11 a.m. Thursday at Galilee Baptist Church, Roxborough Avenue and Mitchell Street. Friends may call at 9 a.m. Burial will be in Chelten Hills Cemetery.