What is the primary function of a pitot-static system?

The primary function of a pitot-static system is indeed to measure airspeed, altitude, and vertical speed. This system utilizes the principles of fluid dynamics, where the pitot tube measures the dynamic pressure of the air to determine airspeed by comparing it to static pressure from the static ports. The static ports, located on the aircraft's fuselage, provide ambient air pressure and are essential for altimetry and vertical speed indicators.

Airspeed is crucial for flight safety and performance, allowing pilots to understand their speed relative to the surrounding air, which is vital for takeoff, landing, and maintaining safe flight. Altitude information from the static pressure is crucial for navigation, ensuring that pilots maintain safe heights above terrain and comply with air traffic control instructions. The vertical speed indicator utilizes the changes in static pressure to inform pilots about their rate of ascent or descent, which is important for managing climb and descent phases during flight.

The other options, while related to aircraft operation, do not pertain to the primary function of the pitot-static system. Fuel efficiency, weight and balance, and engine performance are important factors in aviation, but they are measured and managed through different systems and instruments unrelated to the pitot-static system.