How do you measure the height of an aeroplane?

The height of an airplane is typically measured using an altimeter, which can be barometric or GPS-based. A barometric altimeter measures altitude by comparing the atmospheric pressure outside the aircraft to a standard pressure level, while a GPS altimeter uses satellite signals to calculate the aircraft's position relative to sea level. Pilots usually rely on the altimeter readings displayed in the cockpit for navigation and safety. Additionally, radar systems on the ground can also track and provide altitude information for air traffic control.