When lost the use of gyroscopic instruments, which instrument becomes primary for pitch control?

When the gyroscopic instruments become unavailable, the altimeter is essential for pitch control. This instrument measures the aircraft's altitude based on changes in atmospheric pressure, which provides indirect information about the aircraft's vertical position. Pilots use altitude to maintain level flight, climb, or descend, making the altimeter a crucial reference for managing pitch.

In flight, especially during instrument conditions, maintaining a specific altitude is key to safe navigation and avoiding obstacles. While the airspeed indicator reflects the aircraft’s speed through the air, it does not provide direct information about vertical position. The vertical speed indicator indicates the rate of climb or descent but does not measure altitude directly. The heading indicator is primarily used for directional control and does not assist with pitch management. Thus, in the absence of gyroscopic instruments, the altimeter serves as the primary instrument for controlling pitch effectively.