How is an altimeter typically calibrated?

• A. To a global standard of 30.00 inHg
• B. To its previous flight setting
• C. To local airport elevation or standard pressure
• D. To a predetermined fixed value

Answer: (C)

An altimeter is typically calibrated to local airport elevation or standard pressure to ensure that it accurately reflects the aircraft's altitude above sea level. This process involves setting the altimeter to either the current local altimeter setting obtained from air traffic control or the airport elevation when taking off from or landing at a specific airport. By doing this, pilots can accurately determine their altitude and ensure safe flight operations.

Local adjustments ensure altitude readings are consistent with the atmospheric pressure at that specific location, as pressure changes with weather conditions and altitude. Calibration to a standard pressure setting, like 29.92 inHg, is used primarily when flying at higher altitudes to maintain a consistent reference but does not reflect the local atmospheric conditions accurately at lower elevations. Therefore, calibrating the altimeter to local airport elevation or pressure is crucial for effective altitude measurement during flight operations.