My father told me. His father, my grandfather Sergey Vasilyevich Romanov in the 30s was a teacher of physics and electrical engineering at the NKVD technical school and later at Cheboksary University. In the fall of 1939, he was drafted into the army, in the Air Force. As a result, he got into one of the bomber regiments on TB-3.
TB-3 bomber (open sources)
He came home more than once on vacation