Whenever the time of last contact between an aircraft and ATC exceeds
30 minutes, or if an aircraft has not landed 30 minutes after the pilot has received landing clearance at an airfield and no other contact was established, a Level 1 Alarm internationally known as 'INCERFA' (Uncertainty Phase) is activated. The rescue coordination center requests the flight plan of the particular aircraft via the FIC (Flight Information Center), from which details such as aircraft type, registration, persons on board, route, alternate aerodrome or endurance can be taken.