FAA Private Pilot Helicopter (PRH)Navigation and AirspaceEasy
A pilot needs to measure the distance between two points on a sectional chart that has no printed distance scale nearby. What reliable method should the pilot use?
- AEstimate distance using the compass rose printed around each VOR station
- BUse the mileage scale printed at the bottom of the chart legend only
- CUse the latitude scale along the chart's side border, where 1 minute of latitude equals 1 nautical mile
- DUse the longitude scale along the top border, where 1 minute of longitude equals 1 nautical mile
Show answer & explanationAnswer & explanation
Correct answer: C. Use the latitude scale along the chart's side border, where 1 minute of latitude equals 1 nautical mile
On a sectional chart, each minute of latitude (measured along the side/vertical borders) equals 1 nautical mile. Longitude lines converge toward the poles and do not give a constant distance, so latitude is used for measuring distance.
Why the other options are wrong
- A. Compass roses show magnetic direction, not distance.
- B. A printed scale is convenient but not always available nearby; latitude works everywhere.
- D. Longitude lines converge and don't represent a constant 1 NM per minute.
Measuring Distance on a Sectional Chart
Distance is measured using the latitude scale on the chart's side borders, where each minute of latitude equals 1 nautical mile.
- Latitude lines run east-west, minutes marked on side borders
- 1 minute of latitude = 1 nautical mile everywhere on Earth
- Longitude spacing varies with latitude, so it can't measure distance
Memory trick: Latitude = 'ladder' rungs of nautical miles up the side.