What is the minimum MSL altitude required to reach an outlying field 10 miles away?

To determine the minimum Mean Sea Level (MSL) altitude required to reach an outlying field 10 miles away, one must consider the standard obstacle clearance requirements and the curvature of the Earth.

In general, the formula used to calculate the minimum altitude needed for visibility over the horizon is approximately 1,000 feet of altitude for every 1,000 feet of distance from the observer. Therefore, at a distance of 10 miles, you would need to add additional altitude to ensure a clear line of sight to the field and to compensate for terrain elevation and potential obstacles along the way.

Assuming standard terrain and no additional obstacles, when calculating from the average height of the terrain, a minimum altitude around approximately 5000 feet MSL could provide adequate clearance over most standard obstacles. However, for a 10-mile distance, a slightly higher altitude may be required to ensure visibility to the outlying field, making a MSL of 5100 feet an appropriate choice. This takes into account a typical safety margin to allow for any unexpected terrain variations or obstacles that might not be immediately visible.

This reasoning explains why the minimum required MSL altitude to reach an outlying field 10 miles away would be best represented by 5100 feet M