Flight Redemptions

What is LOM in Aviation? (Locator Outer Marker)

Updated: February 25, 2024

What is a Locator Outer Marker (LOM) in Aviation?

A Locator Outer Marker (LOM) is an important navigational aid used in aviation. It is a radio beacon located at a specific distance from the runway threshold of an airport. The LOM helps pilots determine their position and distance from the airport during approach and landing.

The LOM is typically located on the extended centerline of the runway, usually about 4 to 7 nautical miles away from the runway threshold. It serves as a reference point for pilots to verify their position and to make necessary course corrections before proceeding with the final approach.

The LOM is part of the Instrument Landing System (ILS), which is a ground-based radio navigation system that provides precise vertical and horizontal guidance to aircraft during the approach and landing phases. The ILS consists of several components, including the localizer, glide slope, and the marker beacons. The LOM is one of the marker beacons used in the ILS system.

How Does a Locator Outer Marker Work?

The Locator Outer Marker works by transmitting a specific radio signal that can be received by aircraft equipped with the appropriate navigation receivers. The signal emitted by the LOM is typically a continuous Morse code tone, which is distinct from other marker beacons in the ILS system.

When an aircraft approaches the LOM, the pilot will hear the Morse code tone through the aircraft's audio system. This alerts the pilot that they are at the predetermined distance from the runway threshold. The specific Morse code tone for the LOM is three dashes (---) followed by a silent period.

Upon hearing the LOM signal, the pilot can cross-reference their position with the approach chart and other navigational instruments to confirm their distance from the runway threshold. This helps the pilot maintain situational awareness and make any necessary course corrections to ensure a safe approach and landing.

Importance of the Locator Outer Marker

The Locator Outer Marker plays a crucial role in aviation safety by providing pilots with a reliable reference point during the approach and landing phases. Here are some key reasons why the LOM is important:

Position Verification: The LOM helps pilots verify their position and distance from the runway threshold. This is particularly important in low visibility conditions or during night operations when visual references may be limited.
Course Corrections: If a pilot realizes they are off-course or too high/low during the approach, the LOM provides a point where necessary course corrections can be made. This helps the pilot align the aircraft with the correct approach path and descend to the appropriate altitude.
Backup Navigation: In case of any technical issues with the primary navigation systems, the LOM serves as a backup reference point for pilots. It provides an additional layer of safety and redundancy in the event of equipment failure.

Overall, the Locator Outer Marker is an essential component of the Instrument Landing System and plays a critical role in ensuring safe and accurate approaches and landings at airports.

For more information about the Locator Outer Marker and other aviation terms, you can visit the Federal Aviation Administration's (FAA) website at www.faa.gov. The FAA provides comprehensive resources and guidelines for pilots and aviation professionals.

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