Definition
An ICAO emergency phase declared when there is reasonable certainty that an aircraft and its occupants are threatened by grave and imminent danger or require immediate assistance. It is the most serious of the three ICAO emergency phases (Incerfa, Alerfa, Detresfa) and triggers full search and rescue action.
Plain English
Detresfa is the official emergency stage used worldwide to say an aircraft is almost certainly in serious trouble and needs help right now. When this phase is declared, search and rescue services are launched immediately.
Context Anchor
You may see Detresfa in ICAO emergency, air traffic control, flight service, and search-and-rescue procedures.
Derivation
Detresfa is a coined ICAO codeword built from the French 'détresse' (distress) plus 'fa' for 'phase'. ICAO uses short coined words like this so the meaning is the same in every country, regardless of language.
Why Pilots Care
It triggers immediate activation of rescue coordination centers and search assets to locate and assist the aircraft.
Grounding Statement
Detresfa is the point where the system assumes the aircraft may need rescue or immediate emergency help.
Intuition Check
Do not read “distress” here as ordinary stress or discomfort. In this ICAO term, it means grave, immediate danger or an immediate need for assistance.
Example Sentence 1
After the aircraft missed two scheduled position reports and could not be raised on any frequency, the rescue coordination centre declared Detresfa.
Example Sentence 2
The Detresfa phase requires prompt notification of the appropriate rescue coordination center.