What does the altimeter measure?

• A. Temperature at cruising altitude
• B. The speed of the aircraft
• C. Altitude of the aircraft
• D. Air density changes

Answer: (C)

The altimeter is a crucial instrument in the cockpit that measures the altitude of the aircraft above a specific reference point, typically the mean sea level. It does this by incorporating atmospheric pressure readings, as pressure decreases with an increase in altitude. The altimeter translates these pressure changes into an altitude reading, allowing pilots to maintain proper flight levels and ensure safe navigation.

Understanding how altimeters work is vital for navigating in various airspace environments, where planes must conform to specific altitudes for safety and traffic management. This function directly affects flight operations and is essential for avoiding obstacles and ensuring efficient routes.

The other choices do not accurately reflect the purpose of the altimeter. Temperature at cruising altitude is measured by a different instrument called a thermometer or outside air temperature gauge. The speed of the aircraft is monitored by a separate device known as the airspeed indicator. Changes in air density are typically assessed by instruments that relate to atmospheric conditions but are not the primary function of the altimeter itself.