Which instruments are classified as performance instruments?

The classification of instruments as performance instruments pertains to their functionality in gauging the aircraft's performance in terms of altitude, speed, and vertical movement. Pitch indicators, such as the artificial horizon or altimeter, play a critical role in providing the pilot with information about the aircraft's orientation in the vertical plane and current altitude. The altimeter specifically measures the aircraft's altitude above sea level, indicating how high the aircraft is flying, which is essential for maintaining safety and compliance with air traffic regulations.

In contrast, while turn coordinators, heading indicators, and manifold pressure gauges are important for specific navigational and operational tasks, they do not primarily provide direct data on performance metrics like altitude and pitch. Understanding performance instruments is crucial for pilots, particularly in instrument flight rules (IFR) conditions where visual references are limited, making reliance on these indicators necessary for effective flight management.