Definition
A precision approach and landing guidance system that uses microwave signals to provide pilots with accurate azimuth (lateral), elevation (vertical), and range information during the final approach to a runway. MLS was developed as a more flexible alternative to the Instrument Landing System (ILS), allowing curved and segmented approach paths in addition to straight-in approaches.
Plain English
A landing aid that uses microwave radio signals to guide an aircraft to the runway, telling the pilot exactly where they are left-or-right, up-or-down, and how far out they are.
Context Anchor
Seen in instrument approach, avionics, and airport navigation discussions, especially when comparing landing guidance systems.
Derivation
Microwave refers to very short-wavelength radio signals (in the gigahertz range), which are less affected by terrain and structures than the lower-frequency signals used by ILS. The name simply describes the technology used to deliver landing guidance.
Why Pilots Care
It offers an alternative to the instrument landing system with wider coverage angles and the potential for curved approaches in challenging terrain or weather.
Intuition Check
“Microwave” does not mean a kitchen oven here. It means the system uses a certain kind of radio signal to send landing guidance to the aircraft.
Example Sentence 1
The crew briefed an MLS approach into the airfield because the surrounding terrain made a straight-in ILS impractical.
Example Sentence 2
Because the microwave landing system supports offset approaches, the pilot could avoid obstacles that would block a straight-in path.