🔍 Key Concepts

• Geographic range of visibility (based on curvature of the Earth, not light intensity) • Formula for distance to the horizon in nautical miles using height of eye or object height in feet • Adding the observer’s horizon distance and the object’s horizon distance to find total range

💭 Think About

• How do you convert a height in feet to distance to the horizon in nautical miles? Write the formula and compute it for both 70 ft and 65 ft. • Once you know how far the observer can see to their own horizon and how far the object’s top is above its own horizon, how do you combine those two distances? • After doing both calculations and combining them, which choice is numerically closest to your result?

✅ Before You Answer

• Make sure you use the correct constant in the horizon distance formula (commonly about 1.17 × √height in feet when distance is in nautical miles). • Calculate horizon distance separately for the 70‑ft object and the 65‑ft height of eye before adding. • Check that your final value is reasonable (over 10 nm but under 25 nm) before matching to the nearest answer choice.