Texas Surveyors Practice Exam

What is the protocol for converting magnetic bearings to true bearings?

1. Convert to azimuth and adjust based on declination

2. Use only GPS data for accuracy

3. Apply a standard formula regardless of direction

4. Ignore the declination completely

The correct answer is: Convert to azimuth and adjust based on declination

The protocol for converting magnetic bearings to true bearings involves first converting the magnetic bearing into an azimuth and then adjusting it according to the magnetic declination. Magnetic declination is the angle between magnetic north (where a magnetic compass points) and true north (geodetic north), and it varies by location and can change over time. To convert a magnetic bearing to its corresponding true bearing, you either add or subtract the declination value, depending on whether the declination is east or west. This process is essential for surveying work because true bearings are often required for legal descriptions, mapping, and navigating accurately. Relying solely on GPS data would not address the underlying need to understand how magnetic references relate to geographic references, particularly in traditional surveying practices. Applying a standard formula universally would overlook these necessary adjustments for direction. Ignoring declination completely would result in inaccuracies, as there would be no correlation between where the compass indicates north and true north. Therefore, adjusting for declination is the critical step in ensuring accuracy in the conversion process.