Flying too low is dangerous, many accidents happened due to flying at unsafe altitudes. This is why the MSAW function came to life.

The Minimum Safe Altitude Warning is an automated warning system for air traffic controllers to prevent flying too low and causing terrain accidents.

MSAW has the main purpose of enhancing safety by alerting the air traffic controllers in case an aircraft’s altitude goes lower than the minimum safety altitude in this area. The function can fetch digital terrain or elevation data uses it to decide whether an aircraft is currently below the safe altitude of this area or not. A visual, and in some cases also an audible warning is being generated. It is important to inform the pilots that they are at risk of colliding with obstacles and therefore need to climb.

The following graphic helps to understand the minimum safety altitude: