Most of the aviation research on shared understanding have focused on coordination between cockpit crew. But coordination between pilots and air traffic controllers (ATCs) is critical for flight safety as well. This research determined whether pilots' perception of risk differs from ACTs' when they face the same flight situation. To assess the differences, we had pilots and ATCs evaluate the risk associated with emergency situations. Our risk rating data showed that there were differences in risk perception between pilots and ATCs. Factor analysis further suggested that pilots' risk perception was based on the immediacy of risk whereas ATCs' perception was based on the responsibility for controlling the emergency situation. This research has a practical implication for effective crew resource management (CRM) training.