Before his military service, he graduated from the Transcaucasian Military Preparatory School (1930) and then from the Bataysk Military Aviation School (1935). From 1935 to 1938, Stepanyan worked as a pilot-instructor in Bataysk
In 1938 – 1941, he took flight crew classes at the civil airport of the city of Mineralnye Vody. At the beginning of the Great Patriotic War (1941-1945, basically the Eastern Front of World War II), he took part in the defense of Zaporozhye, Poltava, Odessa, Kakhovka, and Nikolaev.
In September 1941, Stepanian defended Leningrad in the 8th Brigade of the Baltic Fleet. In the autumn of 1942, he was appointed a commander of a squadron. In 1943, he would be appointed the commander of the 57th assault aviation regiment.
In April 1944, Stepanyan along with his assault aviation regiment was sent to the Crimea. He distinguished himself in the battles at Sevastopol, Feodosia, and Sudak. In May 1944, he took part in the smashing of enemy forces in the Gulf of Finland and the liberation of the Baltic states.
Nelson Stepanyan died heroically: he rammed his plane into a German warship on December 14, 1944. By August 18, 1944, Stepanyan had carried out 239 sorties, sunk 53 ships, eliminated 600 vehicles, 80 tanks, and 27 aircraft. For the courage shown in battles on the water and in the air, as well as for his flight skills, Stepanyan received the honorary title “Storm Petrel of the Baltic Sea.”
Many organizations, schools, and streets in the Crimea and Armenia were named in honor of Nelson Stepanyan.
Encyclopedia “Who is who. Armenians”, vol. II, O. Ayvazyan, Yerevan, 2007.