The calculated distance (air line) between Berchem-Sainte-Agathe and Aalst is approximately 12 miles respectively 20 kilometers.
By car or train, the actual journey to Aalst is certainly longer, as only the direct route (as the crow flies) between Berchem-Sainte-Agathe and Aalst has been calculated here.
Air line (approximately)
20 kilometers
11 nautical miles