Definition
A short-wavelength radar sensor operating in the millimeter-wave portion of the radio spectrum (roughly 30–300 GHz) used in some Enhanced Flight Vision Systems to detect runway features, terrain, and obstacles in low-visibility conditions and present them on the pilot's display.
Plain English
A type of radar that uses very short radio waves to 'see' the runway and surroundings through fog, haze, or darkness, and shows the result on a cockpit display so the pilot can fly the approach.
Context Anchor
Seen in discussions of Enhanced Flight Vision Systems (EFVS) used during instrument approaches and low-visibility operations.
Derivation
Named for the wavelength of the radio waves it uses — measured in millimeters rather than centimeters or meters. Shorter wavelengths give finer resolution, which is why this band is useful for picking out runway edges and obstacles.
Why Pilots Care
Enables EFVS-equipped aircraft to continue an approach to lower decision heights by confirming runway environment features when visibility is below published minima.
Grounding Statement
On a low-visibility approach, the system sends radio waves forward, receives the returning echoes, and helps build a picture of what is in front of the aircraft.
Intuition Check
Do not assume this is the same as airborne weather radar. In this EFVS context, millimeter wave radar is mainly a forward-looking sensor for seeing objects and surface features, not just a tool for finding storms.
Example Sentence 1
The aircraft's EFVS uses millimeter wave radar to display the runway environment during approaches in fog.
Example Sentence 2
EFVS combines millimeter wave radar returns with infrared sensors to present a composite view of the runway threshold.