MM

Middle Marker (MM) Definition

The Middle Marker, also known as MM, is a radio beacon located in the middle of the Instrument Landing System (ILS) approach path. It emits a continuous signal that helps pilots identify their position during the landing approach.

The MM is typically located at a distance of approximately 1,500 feet from the runway threshold and at an altitude of 200 feet above the ground. When passing over the MM, pilots should be aligned with the runway centerline and descend to an altitude of 200 feet.

The MM serves as a vital reference point for pilots, helping them accurately position the aircraft during the landing approach. It is an essential component of the ILS system, along with the localizer and glide slope.

The accurate and timely use of the MM is crucial for safe and efficient landings, particularly in low-visibility conditions. It is an indispensable tool for pilots and air traffic controllers, helping to ensure the safety of passengers, crew, and aircraft.