Which instrument is used to determine how high an aircraft is flying?

• A. Vertical speed indicator
• B. Attitude indicator
• C. Altimeter
• D. Airspeed indicator

Answer: (C)

The altimeter is the instrument used to determine how high an aircraft is flying. It measures the aircraft's altitude based on the atmospheric pressure outside the aircraft. As an aircraft ascends, the air pressure decreases, and the altimeter, which is calibrated to read this change, indicates a higher altitude. Pilots use altimeters to maintain safe flying heights, adhere to air traffic control instructions, and navigate accurately.

In contrast, the vertical speed indicator measures how quickly an aircraft is climbing or descending but does not provide information about the actual altitude. The attitude indicator shows the orientation of the aircraft relative to the horizon, while the airspeed indicator measures the speed of the aircraft relative to the surrounding air. Each of these instruments serves a distinct purpose, but only the altimeter provides altitude information.