The calculated distance (air line) between Kostelec nad Orlicí and Třinec is approximately 114 miles respectively 183 kilometers.
By car or train, the actual journey to Třinec is certainly longer, as only the direct route (as the crow flies) between Kostelec nad Orlicí and Třinec has been calculated here.
Air line (approximately)
183 kilometers
99 nautical miles