What type of instrument shows the balance of the aircraft?

• A. The airspeed indicator
• B. The inclinometer or spirit level on the turn coordinator
• C. The altitude indicator
• D. The vertical speed indicator

Answer: (B)

The inclinometer, often referred to as the spirit level or part of the turn coordinator, is the instrument that indicates the balance of the aircraft. Its primary function is to display whether the aircraft is level or in a coordinated turn. The inclinometer measures the angle of the aircraft in relation to the vertical plane, which is essential for maintaining proper flight attitude and performance during maneuvers.

Recognizing the aircraft's balance is crucial for safe flying, as uncoordinated flight can lead to adverse aerodynamic effects such as stalls or spins. The inclinometer alerts the pilot to make corrections to the ailerons or rudder to maintain balanced flight, especially during turns.

In contrast, the other instruments do not provide information about balance. The airspeed indicator measures the aircraft's speed through the air, the altitude indicator shows the aircraft's height above sea level, and the vertical speed indicator displays the rate of ascent or descent. None of these provide a direct measure of the aircraft's lateral balance, making the inclinometer the correct choice for this question.