Understanding Latitude and Longitude
Latitude and longitude help pilots find exact locations on aeronautical charts. For the FAA Part 107 exam, remote pilots should understand the basic grid system used on sectional charts and how coordinates are written.
What Are Latitude and Longitude?
We use two measurements — latitude and longitude — to find any location on Earth. These measurements are based on imaginary lines drawn around the globe.
Latitude
Latitude measures how far north or south a point is from the Equator. Lines of latitude run east and west across the map.
Think of latitude lines like the rungs of a ladder. The Equator is 0° latitude, and the North and South Poles are 90°.
Insert ladder example or diagram here.
Longitude
Longitude measures how far east or west a point is from the Prime Meridian, an imaginary line that runs through Greenwich, England.
Lines of longitude run north and south and meet at the poles. The Prime Meridian is 0° longitude, and longitude extends to 180° east and 180° west.
How Coordinates Are Written
Coordinates are usually written in degrees, minutes, and sometimes seconds. One degree equals 60 minutes, and one minute equals 60 seconds.
39° 57.0′ N, 75° 11.0′ WThis means the location is 39 degrees and 57 minutes north of the Equator, and 75 degrees and 11 minutes west of the Prime Meridian.
Modern GPS units may show decimal degrees, but sectional charts commonly use degrees and minutes.
Key Points to Remember
- Parallels are lines of latitude.
- Latitude lines never intersect.
- Meridians are lines of longitude.
- Longitude lines meet at the poles.
- Each degree is divided into 60 minutes.
Reading Sectional Charts
Sectional charts use latitude and longitude lines to create a large grid. Horizontal lines show latitude. Vertical lines show longitude.
Smaller tick marks between the whole-degree lines help pilots find more exact coordinates.
Exam Tip
When reading minutes on a chart, think of a clock. Thirty minutes is halfway between two degree markings — not 50 percent of a decimal number.
This is a common point of confusion on the Part 107 exam.
