Position error in airspeed measurement is caused by what?

• A. Caused by errors in outside air temperature.
• B. Caused by incorrect pressure at the static port.
• C. Caused by GPS signal interference.
• D. Caused by engine torque.

Answer: (B)

Position error in airspeed measurement comes from the static port not sampling the true ambient static pressure. The airspeed indicator relies on the difference between ram (pitot) pressure and static pressure to derive dynamic pressure. If the static port experiences pressure that is higher or lower than the true atmospheric pressure—often due to its location relative to the airflow around the airplane or flow disturbances—the indicated airspeed will be distorted. In other words, incorrect static pressure at the port leads to an erroneous IAS.

The other options don’t produce this type of error: outside air temperature changes affect density and TAS through the IAS/CAS/TAS relationships, GPS interference doesn’t affect the pitot-static system, and engine torque has no direct effect on the airspeed indication.