Definition

A ground-based safety net intended to warn the controller about increased risk of controlled flight into terrain accidents by generating, in a timely manner, an alert of aircraft proximity to terrain or obstacles.

Source: EUROCONTROL

Description

Minimum Safe Altitude Warning (MSAW) is a ground-based safety net intended to warn the air traffic controller (ATCO) about flights that are predicted to shortly be in close proximity to terrain or obstacles (i.e. aircraft-terrain conflicts).