What is an inclinometer and how is it used in flight?

• A. An instrument consisting of a curved glass tube, housing a glass ball, damped with a fluid similar to kerosene. It may be used to indicate inclination, as a level, or in turns to show gravity vs centrifugal force
• B. An instrument used to measure air temperature
• C. An instrument to measure altitude
• D. An instrument to measure engine oil pressure

Answer: (A)

An inclinometer is a simple level-type instrument that uses a curved glass tube with a small glass ball inside a damping fluid. The ball slides in the tube to show tilt relative to the aircraft’s longitudinal axis, acting as a level to indicate inclination. In flight, this tool helps you confirm level flight and, during turns, reveals the balance between gravity and the centrifugal force acting on the airplane. The ball’s position tells you if you’re banked appropriately and whether your turn is coordinated, since it responds to the net acceleration the aircraft experiences.

The other options describe instruments that measure air temperature, altitude, and engine oil pressure, which are unrelated to tilt or level.