Definition
A sensor system, mounted on the aircraft and aimed forward along the flight path, that detects heat (infrared energy) emitted by objects in the scene ahead and converts it into a real-time image displayed to the pilot. In an Enhanced Flight Vision System (EFVS), the FLIR image is shown on a head-up display so the pilot can see runway environment features — such as runway edges, threshold, approach lights, and terrain — in darkness, haze, smoke, or light fog conditions where the natural view through the windscreen is degraded.
Plain English
A forward-aimed heat-sensing camera that produces a live picture of what's ahead of the aircraft, showing warmer and cooler objects so the pilot can see the runway and surroundings even when normal vision is limited.
Context Anchor
Seen in Enhanced Flight Vision Systems discussions, especially for instrument approaches where the pilot may use sensor imagery to help identify the runway environment.
Derivation
Forward-looking means aimed ahead of the aircraft along the flight path (as opposed to side-looking or downward-looking sensors). Infrared refers to a band of light just beyond what the human eye can see, where warm objects glow brightly. So a forward-looking infrared sensor is simply a heat-picture camera pointed where the airplane is going.
Why Pilots Care
Allows identification of the runway environment and obstacles at lower visibility than unaided vision, supporting safe continuation of an approach.
Analogy
It is like a camera pointed out the front of the aircraft, but instead of depending mainly on visible light, it builds its picture from heat energy.
Intuition Check
FLIR does not mean the pilot can see through all weather or through solid objects. It means the aircraft has a forward-facing infrared sensor that may improve what the pilot can see in some low-visibility situations.
Example Sentence 1
On the approach into low visibility, the FLIR image on the head-up display showed the runway threshold clearly before the pilot could see it through the windscreen.
Example Sentence 2
FLIR imagery showed the approach lights clearly enough for the crew to continue the landing below published minimums.