Contributed by James Hood, Team Leader Calibration Services
A tool can be precise and not accurate, accurate but not precise or both.
At the Duncan Aviation Calibration Lab we are often asked to clarify the difference between aircraft tool precision and tool accuracy.
Precision
Precision is the measure of exactness. It refers to how closely each unit of measure agrees with another. A precise tool will get the same measurement each time.
Accuracy
Accuracy is a measure of rightness or how close a measured value agrees with the correct value. An aircraft tool is accurate if it correctly reflects the size of the unit being measured.
A tool can be precise and not accurate, accurate but not precise or both. For example: a tape measure with increments of 1/32nd of an inch is very precise. The distance between measure marks is small. However, when measuring a bolt known to be exactly one inch, a tape measure with 1/8th inch increments may be more accurate.
It is important to note that just because an aircraft tool is more precise does not mean it is more accurate and accurate tools do not have to have the best precision. The best tools are those tools that have the precision for the job with a good enough accuracy.
Duncan Aviation's Calibration Services has test and calibration capabilities for a multitude of aircraft tools and instruments that routinely require calibration. Contact us for all of your aircraft instrument and tool calibration needs. Save money on your instrument calibrations by bringing your tools along on your next Duncan Aviation maintenance event.
If you have any questions or comments about this, contact Duncan Calibration Services at 402.479.1698.
James Hood is the Team Leader for Duncan Aviation Calibration Services. He specializes in keeping all the tools utilized by Duncan Aviation’s aviation technicians and customers calibrated and ready for service. His aviation career began in 1999.
