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SESK: Stuff Everyone Should Know · sesk.info/drone-obstacle-agl-in-parentheses

On a sectional, an obstacle shows 1549 with (1049) below it. What is the number in parentheses?

Height above ground level (AGL); the top number is the MSL elevation.

  1. Height above ground level ✔
  2. Height above mean sea level
  3. Distance to the nearest airport

Why: Sectionals show the obstacle's top in feet above mean sea level, with its height above the ground in parentheses underneath. In very crowded areas, the AGL number may be left off.

Huh, didn't know that: Sectionals typically show man-made obstacles taller than 200 feet AGL, and new towers may not be on your chart yet.

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Sources

  1. FAA Aeronautical Chart Users' Guide (VFR Terms and Symbols) https://aeronav.faa.gov/user_guide/cug-complete_20260709.pdf

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