Definition
A dedicated in-flight radio service formerly provided by Flight Service Stations to give pilots real-time weather information, hazardous weather updates, and PIREPs (pilot reports) tailored to the aircraft's route, altitude, and position. It was historically contacted on the common frequency 122.0 MHz below 18,000 feet using the call sign 'Flight Watch.' Note: EFAS as a separate service was discontinued by the FAA in 2015; the same functions are now handled by regular Flight Service on standard frequencies, though older FAA materials still describe the service by name.
Plain English
An in-flight radio service pilots could call for current weather, weather hazards, and reports from other pilots along their route. You called 'Flight Watch' on a single common frequency and got weather information specific to where you were flying.
Context Anchor
Seen in aeronautical decision-making discussions about outside resources a pilot can use before or during a flight, especially when weather is changing.
Derivation
En Route' comes from French meaning 'on the way' — i.e., while you're flying, not on the ground. 'Flight Watch' was chosen as the call sign because the service was meant to 'watch over' your flight by keeping you updated on weather as you went.
Why Pilots Care
Supplies real-time weather details that help pilots adjust routes and avoid hazardous conditions.
Intuition Check
Flight Watch did not control the airplane or give traffic separation. It was a weather-information resource for pilots already in flight.
Example Sentence 1
Older training materials describe contacting Flight Watch on 122.0 to get an updated weather picture before crossing the mountains.
Example Sentence 2
Flight Watch advised of building thunderstorms ahead and suggested an alternate heading.