The calculated distance (air line) between San Tung Chung Hang and Kai Tak is approximately 17 miles respectively 27 kilometers.
By car or train, the actual journey to Kai Tak is certainly longer, as only the direct route (as the crow flies) between San Tung Chung Hang and Kai Tak has been calculated here.
Air line (approximately)
27 kilometers
14 nautical miles