Complex sentence: Pokhara Airport is a diversion airport for the main airport TIA in times of problems such as fog, and due to short runway and crowded apron often must re-divert flights to third airports with even shorter runways.
Split into simpler sentences: Pokhara Airport is a diversion airport for the main airport TIA in times of problems such as fog. Due to a short runway and crowded apron, flights must often be re-diverted to third airports with even shorter runways.