The calculated distance (air line) between Akhtubinsk and Chyorny Yar is approximately 15 miles respectively 25 kilometers.
By car or train, the actual journey to Chyorny Yar is certainly longer, as only the direct route (as the crow flies) between Akhtubinsk and Chyorny Yar has been calculated here.
Air line (approximately)
25 kilometers
13 nautical miles