The calculated distance (air line) between Sŏnbong and Changam-ch’on is approximately 146 miles respectively 235 kilometers.
By car or train, the actual journey to Changam-ch’on is certainly longer, as only the direct route (as the crow flies) between Sŏnbong and Changam-ch’on has been calculated here.
Air line (approximately)
235 kilometers
127 nautical miles