What is a supporting instrument during a constant airspeed descent?

In the context of a constant airspeed descent, the supporting instrument is the airspeed indicator. This instrument is crucial because it provides real-time feedback on the aircraft's speed, allowing the pilot to maintain the desired airspeed throughout the descent. Maintaining a constant airspeed is vital for ensuring stable flight and avoiding excessive descent or potential stall conditions.

During a constant airspeed descent, it is essential that the pilot closely monitors the airspeed to make any necessary adjustments in engine power or pitch attitude. If the airspeed indicator shows that the aircraft is descending at an unintended rate, the pilot can respond promptly to maintain the desired profile.

While the attitude indicator, vertical speed indicator, and altimeter all play important roles in guiding the aircraft during a descent, they do not directly measure and support the specific airspeed requirement as effectively as the airspeed indicator does. The attitude indicator provides data regarding the aircraft's orientation in space, the vertical speed indicator indicates the rate of ascent or descent, and the altimeter measures altitude. However, none of these instruments focuses on the critical aspect of regulating airspeed, making the airspeed indicator the most relevant supporting instrument for this scenario.