I recently drove by what seemed like an unusually tall structure and used Google Maps satellite view, its distance measurement tool, and basic trigonometry to calculate that this building (some kind of grain silo at a poultry processing plant) was 175 feet tall above the ground.
But, it does not show up on the sectional map. Other nearby structures, mostly 300-350 feet or greater, do indeed show on the map.
At what minimum height above terrain does a vertical structure need to be indicated on a sectional map?