A generic term meaning, as the case may be, uncertainty phase, alert phase, or distress phase (ICAO). An uncertainty phase is a situation in which an uncertainty exists regarding the safety of an aircraft and its occupants. The code word for this phase is INCEFRA. The alert phase, or ALEFRA, is a situation in which there is apprehension about the safety of an aircraft and its occupants. This phase begins following INCEFRA, when the communication search has failed to reveal any news of the aircraft; an aircraft that has been cleared fails to land within five minutes after the estimated time of landing and communication has not been reestablished with the aircraft; or information has been received that indicates that the operating efficiency of the aircraft has been impaired but not to the extent that a forced landing is likely. The distress phase, or DETRESFA, is a situation where there is a reasonable certainty that an aircraft and its occupants are threatened by grave and imminent danger or require immediate assistance. This phase begins when the fuel on board is believed exhausted or insufficient to enable the aircraft to land safely; information is received that indicates the operating efficiency of the aircraft has been impaired to the extent that a forced landing is likely; or information is received that an aircraft is about to make, or has made, a forced landing.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved