Safety nets help prevent imminent or actual hazardous situations from developing into major incidents or even accidents. Safety nets, for airborne phases of flight and for preventing collisions between aircraft or with terrain or obstacles, are either ground-based or airborne.
Ground-based safety nets are an integral part of the air traffic management (ATM) system. Using primarily air traffic service (ATS) surveillance data, they provide warning times of up to two minutes. Upon receiving an alert, air traffic controllers are expected to immediately assess the situation and take appropriate action.