What type of navigation does a 'Horizon Indicator' assist with?

The Horizon Indicator is a crucial instrument in an aircraft's cockpit that provides pilots with visual information regarding the aircraft's orientation relative to the Earth. Specifically, it helps in attitude navigation, indicating whether the aircraft is in level flight or in a banked turn. This is essential, especially in poor visibility conditions, as it allows pilots to maintain control of the aircraft by showing the pitch (nose up or down) and roll (left wing down or right wing down) orientation.

The Horizon Indicator displays a synthetic horizon, which helps the pilot determine if the wings are level and if the aircraft is climbing, descending, or in level flight. By effectively interpreting the information from the Horizon Indicator, pilots can ensure that the aircraft's attitude is stable, which is vital for safe maneuvering and navigation.

This tool does not assist specifically with ground navigation, speed navigation, or vertical navigation. Ground navigation uses different instruments, such as GPS or terrain mapping tools, to provide geographic location data. Speed navigation refers to instruments that measure airspeed, while vertical navigation instruments help track altitude. The Horizon Indicator's primary function is to convey the aircraft’s attitude, confirming that the answer focusing on attitude navigation is definitively correct.