Understanding “What is Outer Marker on Cessna 172?” is essential for pilots operating this widely used general aviation aircraft. The Outer Marker, often abbreviated as OM, is an important navigation aid during instrument approaches and landing procedures. For pilots flying the Cessna 172, familiarity with the Outer Marker enhances situational awareness and aids in maintaining safe and precise approaches to airports under instrument flight rules (IFR).
Role and Function of the Outer Marker on Cessna 172
The Outer Marker (OM) is a fixed navigation beacon located along the instrument landing system (ILS) approach path, typically found 4 to 7 nautical miles from the runway threshold. For the Cessna 172, which is often equipped with traditional avionics systems including Marker Beacon Receivers, the OM signifies a specific point where the aircraft crosses the final approach fix. This marker is crucial as it alerts pilots that they are aligned properly with the glide slope descent path.
The OM emits a low-frequency signal at 75 MHz. This signal triggers an audible tone and a visual indicator on the Cessna 172’s marker beacon receiver panel. The tone emitted is distinctive, a slow series of dashes for the outer marker, helping distinguish it from the middle marker and inner marker signals. The reception radius of an Outer Marker is approximately 0.5 nautical miles, ensuring precise positional awareness as the pilot descends.
Technical Specifications and Operation of the Outer Marker on Cessna 172
The Outer Marker operates at a frequency of 75 MHz and is positioned on the extended centerline of the runway to assist with approach sequencing. On the Cessna 172, the marker beacon receiver utilizes a panel lamp and an audio annunciation system to communicate the passage over the Outer Marker. Specifically, when the aircraft crosses the OM, the pilot hears a long dashing tone, accompanied by a blue light illuminating on the marker beacon indicator located typically on the instrument panel near the radio stack.