MLS-Microwave Landing System basics

MLS avionic system is a approach landing navigational aids and it stands for Microwave Landing System. It provides Aircraft guidance for curved or straight or segmented flight path landing. The main outputs obtained using MLS are bearing, slant distance, and altitude in the approach terminal area. Also it is important to mention the MLS system is exclusively used by military due to its flexibility in Approach Landing as opposed to the civilian ILS.

MLS Microwave Landing System

On the Ground following are features both in azimuth Tx and elevation Tx.
Azimuth Tx:
•   Function: Provides bearing information.
•   NAV: Horizontal Guidance.
•   Quantity per runway: 2
•   Location: One is placed at the end of the runway, and the other
one at the begging.
•   Frequency of operation is : SHF  5.031 to 5.0907 GHz
with he number of Channels equal to 200
•   Horizontal Range of Operation: 37 km
•   Deviation from Centerline is approx. +/- 40 Degree.

Elevation Tx:
•  Function: Provides ALT information.
•  NAV: Vertical Guidance.
•  Quantity per runway: 1
•  Location: On the side of the runway.
•  Frequency of operation is SHF from 5.031 to 5.0907 GHz
•  Number of Channels: 200
•  Vertical Range of Operation is approx. 6 km
•  Typical MLS Inclination is about 8 Degree
•  Deviation from MLS is approx. +/- 7 degree

In the Aircraft, MLS receiver system operates in SHF band. Primary outputs from MLS are bearing/slant distance and altitude. Secondary outputs from MLS (Microwave landing system) are meteorological information, runway status etc.


•  Improved guidance accuracy with greater coverage area.
•  Provide flexible landing path NAV.
•  Offers guidance for missed approaches and departure NAV.
•  MLS has low sensitivity from weather conditions and airport GNS traffic as oppose to ILS.
•  MLS offers 200 frequency channels, 10-times more than ILS.
•  maintenance and installation of MLS is cheaper.


The use of Microwave Landing System is not much in use in civilian aircrafts.

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