Flight Redemptions

What is MB in Aviation? (Marker Beacon)

Updated: March 03, 2024

The Marker Beacon (MB) in Aviation

In aviation, the Marker Beacon (MB) plays a crucial role in providing pilots with important navigational information during instrument approaches. The Marker Beacon is a ground-based radio transmitter that emits signals that can be received by an aircraft's marker receiver. These signals serve as reference points for pilots, indicating specific locations along the approach path to the runway. In this article, we will explore the significance of Marker Beacons in aviation and their role in ensuring safe and accurate instrument approaches.

The Function of Marker Beacons

Marker Beacons are installed at designated points along the approach path to a runway, typically located at distances of 1.0, 0.5, and 0.1 nautical miles from the runway threshold. Each Marker Beacon emits a distinct and identifiable radio signal that is received by the aircraft's marker receiver. These signals are used to indicate specific altitudes or distances from the runway, providing pilots with valuable information during instrument approaches.

There are three types of Marker Beacons: the Outer Marker (OM), the Middle Marker (MM), and the Inner Marker (IM). Each marker has its own unique signal and is associated with a specific altitude or distance from the runway threshold. Let's take a closer look at each type of Marker Beacon:

The Outer Marker (OM)

The Outer Marker is the marker farthest from the runway threshold, typically located at a distance of 1.0 nautical mile. When an aircraft passes over the Outer Marker, the marker receiver detects the distinctive signal and alerts the pilot. This signal serves as an important reference point, indicating that the aircraft is at the correct distance from the runway and is aligned with the approach path. It also serves as a reminder for pilots to configure the aircraft for landing, such as extending flaps and lowering landing gear.

The Outer Marker signal is typically a series of dots transmitted at a frequency of 75 MHz. The pilot will hear the dots through the aircraft's audio panel, providing an audible indication of the aircraft's position relative to the runway. This signal is an essential component of instrument approaches, ensuring that pilots are properly aligned and configured for landing.

It is worth noting that not all airports have Outer Markers. In some cases, an airport may only have Middle and Inner Markers, or even just the Inner Marker. The presence of Marker Beacons depends on the specific approach procedure and the airport's infrastructure.

The Middle Marker (MM)

The Middle Marker is located at a distance of 0.5 nautical miles from the runway threshold, halfway between the Outer Marker and the runway. It serves as an additional reference point for pilots, indicating that they are approaching the runway and should prepare for landing. The Middle Marker signal is typically a series of dashes transmitted at a frequency of 75 MHz.

When the aircraft passes over the Middle Marker, the marker receiver detects the signal and alerts the pilot. This signal provides pilots with important information about their position relative to the runway, ensuring that they are on the correct glide path and are prepared to make a safe landing. The Middle Marker is particularly valuable during low-visibility conditions, as it helps pilots maintain situational awareness and make precise instrument approaches.

The Inner Marker (IM)

The Inner Marker is the closest marker to the runway threshold, typically located at a distance of 0.1 nautical miles. It serves as the final reference point for pilots, indicating that they are approaching the runway and should prepare for landing. The Inner Marker signal is typically a continuous tone transmitted at a frequency of 75 MHz.

When the aircraft passes over the Inner Marker, the marker receiver detects the signal and alerts the pilot. This signal confirms that the aircraft is at the correct distance from the runway threshold and is aligned with the approach path. It serves as a final reminder for pilots to complete their landing checklist and ensure that the aircraft is configured for a safe landing.

Conclusion

The Marker Beacon (MB) is an essential component of instrument approaches in aviation. Through their distinct and identifiable signals, Marker Beacons provide pilots with valuable navigational information, indicating specific altitudes or distances from the runway threshold. The Outer Marker, Middle Marker, and Inner Marker serve as reference points along the approach path, ensuring that pilots are properly aligned and prepared for landing. These markers play a crucial role in maintaining situational awareness, especially during low-visibility conditions. By utilizing the information provided by Marker Beacons, pilots can execute safe and accurate instrument approaches, contributing to the overall safety of aviation operations.

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