What is the primary use of altitude measurement in aviation?

Altitude measurement plays a crucial role in aviation primarily by ensuring safety and performance during flight. By knowing the altitude at which an aircraft is flying, pilots can avoid terrain and obstacles, ensure appropriate separation from other aircraft, and operate within controlled airspace regulations. Altitude also directly influences aircraft performance, affecting lift, drag, and engine efficiency.

Maintaining the correct altitude helps in optimizing fuel consumption, enhancing passenger comfort, and ensuring compliance with air traffic control directives. The use of altitude in aviation is not limited to navigation; it encompasses a wide range of operational aspects that contribute to the overall safety and efficacy of flight operations.

Other options suggest limited or irrelevant uses of altitude measurement, such as suggesting that it's only for navigation or unnecessary for commercial flights, which overlooks the comprehensive importance of altitude in all facets of safe flying.