Nearly 1,500 flights cancelled at Saudi's 3 busiest airports, Umrah pilgrims affected. Nearly 1,500 flights were cancelled on Monday at Saudi Arabia’s three busiest airports in Riyadh, Jeddah and Dammam. This comes after attack by Iran-backed Houthis on Riyadh’s King Khalid International Airport that killed 13 people and injured over 300. The disruptions have also affected religious travel, with Umrah pilgrims among those caught up in the attacks and subsequent cancellations.