1. What is Great Circle Distance?

The great-circle distance is the shortest distance between two points on the surface of a sphere, measured along the surface of the sphere. This calculation is essential for navigation and aviation.

2. How Does the Calculator Work?

The calculator uses the great circle distance formula:

Where:

• \( Lat1, Lon1 \) — Latitude and longitude of first point (degrees)
• \( Lat2, Lon2 \) — Latitude and longitude of second point (degrees)
• 3440.1 — Conversion factor to nautical miles (Earth's radius in nautical miles)

Explanation: The formula calculates the central angle between two points and converts it to distance using the Earth's radius.

3. Importance of Nautical Miles

Details: Nautical miles are used worldwide for maritime and aviation navigation because they relate directly to latitude (1 nautical mile = 1 minute of latitude).

4. Using the Calculator

Tips: Enter coordinates in decimal degrees (positive for North/East, negative for South/West). For example, New York is approximately 40.7128° N, 74.0060° W.

5. Frequently Asked Questions (FAQ)

Q1: Why use nautical miles instead of kilometers or miles?
A: Nautical miles are the standard unit for air and sea navigation as they correspond to minutes of latitude, making chart reading and navigation simpler.

Q2: How accurate is this calculation?
A: It assumes a perfect sphere. The Earth is actually an oblate spheroid, but the difference is typically less than 0.5%.

Q3: What's the difference between great circle and rhumb line?
A: Great circle is the shortest path but requires constant course adjustment. Rhumb lines maintain constant bearing but are longer.

Q4: Can I use this for very short distances?
A: For distances under 20 nautical miles, simpler flat-earth approximations may be more practical.

Q5: How do I convert to kilometers or statute miles?
A: 1 nautical mile = 1.852 km = 1.15078 statute miles. Multiply the result by these factors.