What is the function of an altimeter?

The function of an altimeter is to measure the aircraft's altitude by comparing local air pressure with a standard reference. An altimeter operates based on the principle that atmospheric pressure decreases with an increase in altitude. It uses a calibrated barometric pressure sensor to detect the current air pressure and compares it to a standard atmospheric pressure at sea level (usually 29.92 inches of mercury, or 1013.25 hPa). This helps pilots determine their elevation above sea level, which is essential for maintaining safe flight levels, avoiding terrain, and communicating with air traffic control regarding altitude. Understanding this function is critical for pilots as altitude data plays a vital role in navigation and safety.