The calculated distance (air line) between Náměšť nad Oslavou and Třinec is approximately 117 miles respectively 189 kilometers.
By car or train, the actual journey to Třinec is certainly longer, as only the direct route (as the crow flies) between Náměšť nad Oslavou and Třinec has been calculated here.
Air line (approximately)
189 kilometers
102 nautical miles