What is the result of deceleration when using the attitude indicator?

When deceleration occurs in flight, the attitude indicator reflects this by showing a change in the aircraft's pitch attitude. Specifically, the horizon bar will move upward in relation to the aircraft symbol. This happens because the airplane, being in a decelerating state, tends to pitch up relative to the horizontal plane. As the airplane slows down, inertia causes it to maintain a level attitude momentarily, leading the indicator to show a rise in the horizon bar.

The movement of the horizon bar upward essentially conveys that the airplane's nose is pitching higher as it decelerates, allowing pilots to adjust their pitch attitude to maintain level flight as needed. Understanding this function is crucial for effective aircraft control during various phases of flight where deceleration is a factor, such as during approach or landing.