How far from the runway threshold is the Outer Marker (OM)?

How far from the runway threshold is the Outer Marker (OM)?

• A. 2 to 4 nm
• B. 8 to 10 nm
• C. 1 to 2 nm
• D. 4 to 7 nm

Answer: (D)

Understanding where the Outer Marker sits on an ILS approach helps you gauge where you are in the final phase of the approach. The Outer Marker is placed farther from the runway threshold than the other marker beacons and serves as a clear cue that you are on the correct localizer and glideslope path while you’re still high enough to set up your descent. The standard placement is about 4 to 7 nautical miles from the threshold, along the approach course. This spacing gives you a timely, predictable reference to begin the final descent and ensures you can comfortably continue down the glideslope as you approach the runway. You’ll typically see a blue marker beacon indication (and hear the associated tone) as you pass the Outer Marker. Since the Middle and Inner Markers sit progressively closer to the runway, the Outer Marker’s 4 to 7 NM distance is the correct range.

Understanding where the Outer Marker sits on an ILS approach helps you gauge where you are in the final phase of the approach. The Outer Marker is placed farther from the runway threshold than the other marker beacons and serves as a clear cue that you are on the correct localizer and glideslope path while you’re still high enough to set up your descent. The standard placement is about 4 to 7 nautical miles from the threshold, along the approach course. This spacing gives you a timely, predictable reference to begin the final descent and ensures you can comfortably continue down the glideslope as you approach the runway. You’ll typically see a blue marker beacon indication (and hear the associated tone) as you pass the Outer Marker. Since the Middle and Inner Markers sit progressively closer to the runway, the Outer Marker’s 4 to 7 NM distance is the correct range.