In a constant airspeed descent, which instrument is primary for pitch?

The primary instrument for pitch control during a constant airspeed descent is the attitude indicator. This instrument provides the pilot with information about the aircraft's orientation relative to the horizon, which is crucial for maintaining the desired pitch attitude.

In a constant descent where the airspeed needs to be maintained, the pilot adjusts the pitch of the aircraft to control both the rate of descent and to ensure that the airspeed remains stable. The attitude indicator shows whether the nose of the aircraft is above or below the horizon, allowing the pilot to make precise adjustments in pitch. This is essential for ensuring that the descent does not result in excessive speed changes or altitude loss beyond what is intended.

While other instruments like the vertical speed indicator and altimeter provide useful information about the rate of descent and altitude, they do not control pitch directly. The airspeed indicator is critical for monitoring speed but does not indicate pitch attitude. Therefore, in terms of actively managing the pitch in a constant airspeed descent, the attitude indicator is the key instrument.