What are the three types of errors in the airspeed indicator?

• A. Density error, Calibration error, Humidity error
• B. Density error, Instrument error, Position (installation) error
• C. Pressure error, Temperature error, Wind error
• D. Density error only

Answer: (B)

The airspeed indicator relies on pitot-static pressures to translate dynamic pressure into airspeed, so errors come from three main sources: density, the instrument itself, and how the sensing ports are installed. Density error happens because air density changes with altitude and temperature. Since the indicator is calibrated for standard density, the same dynamic pressure can correspond to different speeds in nonstandard air, so indicated airspeed won’t always match true airspeed. Instrument error covers the indicator’s own calibration and condition—leaks in the pitot or static lines, worn parts, or calibration drift—that can produce wrong readings even in steady airflow. Position or installation error arises from the locations of the pitot tube and static ports and the surrounding airflow; if these ports are blocked or in disturbed flow, or if the plumbing is wrong, the pressures measured don’t reflect the true free-stream air, causing erroneous indications, especially with changes in attitude or speed. Other factors like humidity or separate temperature effects are effects that fall under density, not separate error types. So density error, instrument error, and position (installation) error best describe the three kinds of airspeed indicator errors.